purchases-ios/Tests/UnitTests/Networking/HTTPClientTests.swift

//
//  HTTPClientTests.swift
//  PurchasesTests
//
//  Created by RevenueCat.
//  Copyright © 2019 RevenueCat. All rights reserved.
//

import Nimble
import OHHTTPStubs
import OHHTTPStubsSwift
import XCTest

@testable @_spi(Internal) import RevenueCat

/// Generic `ETagManager` type allows subclasses to use either `MockETagManager`
/// or the real `ETagManager`.
class BaseHTTPClientTests<ETag: ETagManager>: TestCase {

    typealias EmptyResponse = VerifiedHTTPResponse<HTTPEmptyResponseBody>.Result
    typealias DataResponse = VerifiedHTTPResponse<Data>.Result
    typealias BodyWithDateResponse = VerifiedHTTPResponse<BodyWithDate>.Result

    var systemInfo: MockSystemInfo!
    var signing: MockSigning!
    var client: HTTPClient!
    var eTagManager: ETag!
    var diagnosticsTracker: DiagnosticsTrackerType?
    var operationDispatcher: OperationDispatcher!

    fileprivate let apiKey = "MockAPIKey"

    override func setUpWithError() throws {
        try super.setUpWithError()

        #if os(watchOS)
        // See https://github.com/AliSoftware/OHHTTPStubs/issues/287
        try XCTSkipIf(true, "OHHTTPStubs does not currently support watchOS")
        #endif

        self.systemInfo = MockSystemInfo(finishTransactions: true)
        self.signing = MockSigning()
        if #available(iOS 15.0, tvOS 15.0, macOS 12.0, watchOS 8.0, *) {
            self.diagnosticsTracker = MockDiagnosticsTracker()
        } else {
            self.diagnosticsTracker = nil
        }
        self.operationDispatcher = OperationDispatcher()
        MockDNSChecker.resetData()

        // Subclasses must initialize `self.eTagManager` before this
        self.client = self.createClient()
    }

    override func tearDown() {
        HTTPStubs.removeAllStubs()

        super.tearDown()
    }

    final func createClient() -> HTTPClient {
        return self.createClient(self.systemInfo)
    }

    fileprivate final func createClient(
        _ systemInfo: SystemInfo,
        operationDispatcher: OperationDispatcher = MockOperationDispatcher()
    ) -> HTTPClient {
        return HTTPClient(apiKey: self.apiKey,
                          systemInfo: systemInfo,
                          eTagManager: self.eTagManager,
                          signing: self.signing,
                          diagnosticsTracker: self.diagnosticsTracker,
                          dnsChecker: MockDNSChecker.self,
                          requestTimeout: defaultTimeout.seconds,
                          operationDispatcher: operationDispatcher)
    }
}

final class HTTPClientTests: BaseHTTPClientTests<MockETagManager> {

    override func setUpWithError() throws {
        self.eTagManager = MockETagManager()

        try super.setUpWithError()
    }

    func testUsesTheCorrectHost() throws {
        let hostCorrect: Atomic<Bool> = false

        let host = try XCTUnwrap(HTTPRequest.Path.serverHostURL.host)
        stub(condition: isHost(host)) { _ in
            hostCorrect.value = true
            return .emptySuccessResponse()
        }

        let request = HTTPRequest(method: .get, path: .mockPath)

        waitUntil { completion in
            self.client.perform(request) { (_: EmptyResponse) in completion() }
        }

        expect(hostCorrect.value) == true
    }

    func testPassesHeaders() {
        let headerPresent: Atomic<Bool> = false

        stub(condition: hasHeaderNamed("Authorization")) { _ in
            headerPresent.value = true
            return .emptySuccessResponse()
        }

        let request = HTTPRequest(method: .post([:]), path: .mockPath)

        waitUntil { completion in
            self.client.perform(request) { (_: EmptyResponse) in completion() }
        }

        expect(headerPresent.value) == true
    }

    func testRequestWithNoNonceDoesNotContainNonceHeader() {
        let request = HTTPRequest(method: .get, path: .mockPath)

        let headers: [String: String]? = waitUntilValue { completion in
            stub(condition: isPath(request.path)) { request in
                completion(request.allHTTPHeaderFields)
                return .emptySuccessResponse()
            }

            self.client.perform(request) { (_: EmptyResponse) in }
        }

        expect(headers).toNot(beEmpty())
        expect(headers?.keys).toNot(contain(HTTPClient.RequestHeader.nonce.rawValue))
    }

    func testGetRequestDoesNotContainPostParametersHeader() {
        let request = HTTPRequest(method: .get, path: .mockPath)

        let headers: [String: String]? = waitUntilValue { completion in
            stub(condition: isPath(request.path)) { request in
                completion(request.allHTTPHeaderFields)
                return .emptySuccessResponse()
            }

            self.client.perform(request) { (_: EmptyResponse) in }
        }

        expect(headers).toNot(beEmpty())
        expect(headers?.keys).toNot(contain(HTTPClient.RequestHeader.postParameters.rawValue))
    }

    func testPostRequestWithDisabledSignatureVerificationDoesNotContainPostParametersHeader() {
        let body = BodyWithSignature(key1: "a", key2: "b")

        let request = HTTPRequest(method: .post(body), path: .postReceiptData)

        let headers: [String: String]? = waitUntilValue { completion in
            stub(condition: isPath(request.path)) { request in
                completion(request.allHTTPHeaderFields)
                return .emptySuccessResponse()
            }

            self.client.perform(request) { (_: EmptyResponse) in }
        }

        expect(headers).toNot(beEmpty())
        expect(headers?.keys).toNot(contain(HTTPClient.RequestHeader.postParameters.rawValue))
    }

    func testRequestIncludesNonceInBase64() {
        let request = HTTPRequest(method: .get, path: .mockPath, nonce: "1234567890ab".asData)

        let headers: [String: String]? = waitUntilValue { completion in
            stub(condition: isPath(request.path)) { request in
                completion(request.allHTTPHeaderFields)
                return .emptySuccessResponse()
            }

            self.client.perform(request) { (_: EmptyResponse) in }
        }

        expect(headers).toNot(beEmpty())
        expect(headers?.keys).to(contain(HTTPClient.RequestHeader.nonce.rawValue))
        expect(headers?[HTTPClient.RequestHeader.nonce.rawValue]) == "MTIzNDU2Nzg5MGFi"
    }

    func testAlwaysSetsContentTypeHeader() {
        let headerPresent: Atomic<Bool> = false

        stub(condition: hasHeaderNamed("content-type", value: "application/json")) { _ in
            headerPresent.value = true
            return .emptySuccessResponse()
        }

        let request = HTTPRequest(method: .post([:]), path: .mockPath)

        waitUntil { completion in
            self.client.perform(request) { (_: EmptyResponse) in completion() }
        }

        expect(headerPresent.value) == true
    }

    func testAlwaysPassesPlatformHeader() {
        let headerPresent: Atomic<Bool> = false

        stub(condition: hasHeaderNamed("X-Platform", value: SystemInfo.platformHeader)) { _ in
            headerPresent.value = true
            return .emptySuccessResponse()
        }

        let request = HTTPRequest(method: .post([:]), path: .mockPath)

        waitUntil { completion in
            self.client.perform(request) { (_: EmptyResponse) in completion() }
        }

        expect(headerPresent.value) == true
    }

    func testAlwaysPassesVersionHeader() {
        let headerPresent: Atomic<Bool> = false

        stub(condition: hasHeaderNamed("X-Version", value: Purchases.frameworkVersion)) { _ in
            headerPresent.value = true
            return .emptySuccessResponse()
        }

        let request = HTTPRequest(method: .post([:]), path: .mockPath)

        waitUntil { completion in
            self.client.perform(request) { (_: EmptyResponse) in completion() }
        }

        expect(headerPresent.value) == true
    }

    func testAlwaysPassesPlatformVersion() {
        let headerPresent: Atomic<Bool> = false

        stub(condition: hasHeaderNamed("X-Platform-Version", value: ProcessInfo().operatingSystemVersionString)) { _ in
            headerPresent.value = true
            return .emptySuccessResponse()
        }

        let request = HTTPRequest(method: .post([:]), path: .mockPath)

        waitUntil { completion in
            self.client.perform(request) { (_: EmptyResponse) in completion() }
        }

        expect(headerPresent.value) == true
    }

    func testAlwaysPassesIsSandboxWhenEnabled() {
        let headerName = "X-Is-Sandbox"
        self.systemInfo.stubbedIsSandbox = true

        let header: Atomic<String?> = nil

        stub(condition: hasHeaderNamed(headerName)) { request in
            header.value = request.value(forHTTPHeaderField: headerName)
            return .emptySuccessResponse()
        }

        let request = HTTPRequest(method: .post([:]), path: .mockPath)

        waitUntil { completion in
            self.client.perform(request) { (_: EmptyResponse) in completion() }
        }

        expect(header.value) == "true"
    }

    func testAlwaysPassesIsSandboxWhenDisabled() {
        let headerName = "X-Is-Sandbox"
        self.systemInfo.stubbedIsSandbox = false

        let header: Atomic<String?> = nil

        stub(condition: hasHeaderNamed(headerName)) { request in
            header.value = request.value(forHTTPHeaderField: headerName)
            return .emptySuccessResponse()
        }

        let request = HTTPRequest(method: .post([:]), path: .mockPath)

        waitUntil { completion in
            self.client.perform(request) { (_: EmptyResponse) in completion() }
        }

        expect(header.value) == "false"
    }

    func testAlwaysPassesIsDebugBuildHeaderInReleaseMode() {
        let headerName = "X-Is-Debug-Build"
        self.systemInfo.stubbedIsDebugBuild = false // "release" mode

        let header: Atomic<String?> = nil

        stub(condition: hasHeaderNamed(headerName)) { request in
            header.value = request.value(forHTTPHeaderField: headerName)
            return .emptySuccessResponse()
        }

        let request = HTTPRequest(method: .post([:]), path: .mockPath)

        waitUntil { completion in
            self.client.perform(request) { (_: EmptyResponse) in completion() }
        }

        expect(header.value) == "false"
    }

    func testAlwaysPassesIsDebugBuildHeaderInDebugMode() {
        let headerName = "X-Is-Debug-Build"
        self.systemInfo.stubbedIsDebugBuild = true

        let header: Atomic<String?> = nil

        stub(condition: hasHeaderNamed(headerName)) { request in
            header.value = request.value(forHTTPHeaderField: headerName)
            return .emptySuccessResponse()
        }

        let request = HTTPRequest(method: .post([:]), path: .mockPath)

        waitUntil { completion in
            self.client.perform(request) { (_: EmptyResponse) in completion() }
        }

        expect(header.value) == "true"
    }

    func testRequestWithStorefrontSendsHeader() {
        let headerName = "X-Storefront"
        self.systemInfo.stubbedStorefront = MockStorefront(countryCode: "USA")

        let header: Atomic<String?> = nil

        stub(condition: hasHeaderNamed(headerName)) { request in
            header.value = request.value(forHTTPHeaderField: headerName)
            return .emptySuccessResponse()
        }

        let request = HTTPRequest(method: .post([:]), path: .mockPath)

        waitUntil { completion in
            self.client.perform(request) { (_: EmptyResponse) in completion() }
        }

        expect(header.value) == "USA"
    }

    func testRequestsWithoutStorefrontDoNotSendHeader() {
        let headerName = "X-Storefront"
        let request = HTTPRequest(method: .post([:]), path: .mockPath)

        self.systemInfo.stubbedStorefront = nil

        let header: Atomic<(value: String?, set: Bool)> = .init((nil, false))

        stub(condition: isPath(request.path)) { request in
            header.value = (value: request.value(forHTTPHeaderField: headerName), set: true)
            return .emptySuccessResponse()
        }

        waitUntil { completion in
            self.client.perform(request) { (_: EmptyResponse) in completion() }
        }

        expect(header.value) == (value: nil, set: true)
    }

    func testCallsTheGivenPath() {
        let request = HTTPRequest(method: .post([:]), path: .mockPath)

        let pathHit: Atomic<Bool> = false

        stub(condition: isPath(request.path)) { _ in
            pathHit.value = true
            return .emptySuccessResponse()
        }

        waitUntil { completion in
            self.client.perform(request) { (_: EmptyResponse) in completion() }
        }

        expect(pathHit.value) == true
    }

    func testSendsBodyData() throws {
        let body = AnyEncodableRequestBody(["arg": "value"])
        let pathHit: Atomic<Bool> = false

        let bodyData = try JSONEncoder.default.encode(body)

        stub(condition: hasBody(bodyData)) { _ in
            pathHit.value = true
            return .emptySuccessResponse()
        }
        let request = HTTPRequest(method: .post(body), path: .mockPath)

        waitUntil { completion in
            self.client.perform(request) { (_: EmptyResponse) in completion() }
        }

        expect(pathHit.value) == true
    }

    func testCallsCompletionHandlerWhenFinished() {
        let request = HTTPRequest(method: .get, path: .mockPath)

        stub(condition: isPath(request.path)) { _ in
            return .emptySuccessResponse()
        }

        waitUntil { completion in
            self.client.perform(request) { (_: EmptyResponse) in
                completion()
            }
        }
    }

    func testHandlesRealErrorConditions() {
        let request = HTTPRequest(method: .get, path: .mockPath)
        let error = NSError(domain: NSURLErrorDomain, code: NSURLErrorUnknown, userInfo: nil)

        stub(condition: isPath(request.path)) { _ in
            let response = HTTPStubsResponse.emptySuccessResponse()
            response.error = error
            return response
        }
        let receivedError = waitUntilValue { completion in
            self.client.perform(request) { (result: EmptyResponse) in
                completion(result.error)
            }
        }

        expect(receivedError).toNot(beNil())
        expect(receivedError?.isServerDown) == false

        switch receivedError {
        case let .networkError(actualError, _):
            expect(actualError.domain) == error.domain
            expect(actualError.code) == error.code
        default:
            fail("Unexpected error: \(String(describing: receivedError))")
        }
    }

    func testServerSide400s() throws {
        let request = HTTPRequest(method: .get, path: .mockPath)
        let errorCode = HTTPStatusCode.invalidRequest.rawValue + Int.random(in: 0..<50)

        stub(condition: isPath(request.path)) { _ in
            let json = "{\"code\": 7101, \"message\": \"something is broken up in the cloud\"}"
            return HTTPStubsResponse(
                data: json.data(using: String.Encoding.utf8)!,
                statusCode: Int32(errorCode),
                headers: [
                    HTTPClient.ResponseHeader.contentType.rawValue: "application/json"
                ]
            )
        }

        let result = waitUntilValue { completion in
            self.client.perform(request) { (response: DataResponse) in
                completion(response)
            }
        }

        expect(result).toNot(beNil())
        expect(result).to(beFailure())

        let error = try XCTUnwrap(result?.error)
        expect(error) == .errorResponse(
            .init(code: .storeProblem,
                  originalCode: 7101,
                  message: "something is broken up in the cloud"),
            HTTPStatusCode(rawValue: errorCode)
        )
        expect(error.isServerDown) == false

        expect(self.signing.requests).to(beEmpty())
    }

    func testServerSide500sWithErrorResponse() throws {
        let request = HTTPRequest(method: .get, path: .mockPath)
        let errorCode = 500 + Int.random(in: 0..<50)

        stub(condition: isPath(request.path)) { _ in
            let json = "{\"code\": 5000,\"message\": \"something is broken up in the cloud\"}"
            return HTTPStubsResponse(
                data: json.asData,
                statusCode: Int32(errorCode),
                headers: [
                    HTTPClient.ResponseHeader.contentType.rawValue: "application/json"
                ]
            )
        }

        let result = waitUntilValue { completion in
            self.client.perform(request) { (response: DataResponse) in
                completion(response)
            }
        }

        expect(result).toNot(beNil())
        expect(result).to(beFailure())

        let error = try XCTUnwrap(result?.error)
        expect(error) == .errorResponse(
            .init(code: .unknownBackendError,
                  originalCode: 5000,
                  message: "something is broken up in the cloud"),
            HTTPStatusCode(rawValue: errorCode)
        )
        expect(error.isServerDown) == true

        expect(self.signing.requests).to(beEmpty())
    }

    func testServerSide500sWithCharsetContentType() throws {
        let request = HTTPRequest(method: .get, path: .mockPath)
        let errorCode = 500 + Int.random(in: 0..<50)

        stub(condition: isPath(request.path)) { _ in
            let json = "{\"code\": 5000,\"message\": \"something is broken up in the cloud\"}"
            return HTTPStubsResponse(
                data: json.asData,
                statusCode: Int32(errorCode),
                headers: [
                    HTTPClient.ResponseHeader.contentType.rawValue: "application/json;charset=utf8"
                ]
            )
        }

        let result = waitUntilValue { completion in
            self.client.perform(request) { (response: DataResponse) in
                completion(response)
            }
        }

        expect(result).to(beFailure())
        let error = try XCTUnwrap(result?.error)

        expect(error) == .errorResponse(
            .init(code: .unknownBackendError,
                  originalCode: 5000,
                  message: "something is broken up in the cloud"),
            HTTPStatusCode(rawValue: errorCode)
        )
        expect(error.isServerDown) == true
    }

    func testServerSide500sWithUnknownBody() throws {
        let request = HTTPRequest(method: .get, path: .mockPath)
        let errorCode = 500 + Int.random(in: 0..<50)

        stub(condition: isPath(request.path)) { _ in
            let json = "The server is broken"
            return HTTPStubsResponse(
                data: json.asData,
                statusCode: Int32(errorCode),
                headers: nil
            )
        }

        let result = waitUntilValue { completion in
            self.client.perform(request) { (response: DataResponse) in
                completion(response)
            }
        }

        expect(result).toNot(beNil())
        expect(result).to(beFailure())

        let error = try XCTUnwrap(result?.error)
        expect(error) == .errorResponse(
            .init(code: .unknownError,
                  originalCode: BackendErrorCode.unknownError.rawValue,
                  message: nil),
            HTTPStatusCode(rawValue: errorCode)
        )
        expect(error.isServerDown) == true

        expect(self.signing.requests).to(beEmpty())

        self.logger.verifyMessageWasNotLogged("Couldn't decode data from json")
    }

    func testInvalidJSONAsDataDoesNotFail() {
        let request = HTTPRequest(method: .get, path: .mockPath)

        let statusCode = HTTPStatusCode.success
        let data = "{this is not JSON.csdsd".data(using: String.Encoding.utf8)!

        stub(condition: isPath(request.path)) { _ in
            return HTTPStubsResponse(
                data: data,
                statusCode: Int32(statusCode.rawValue),
                headers: nil
            )
        }

        let result = waitUntilValue { completion in
            self.client.perform(request) { (response: DataResponse) in
                completion(response)
            }
        }

        expect(result).toNot(beNil())
        expect(result).to(beSuccess())
        expect(result?.value?.body) == data
    }

    func testParseError() throws {
        struct CustomResponse: Decodable, HTTPResponseBody {
            let data: String
        }

        let request = HTTPRequest(method: .get, path: .mockPath)
        let errorCode = HTTPStatusCode.success.rawValue

        stub(condition: isPath(request.path)) { _ in
            let json = "{this is not JSON.csdsd"
            return HTTPStubsResponse(
                data: json.data(using: String.Encoding.utf8)!,
                statusCode: Int32(errorCode),
                headers: nil
            )
        }

        let result = waitUntilValue { completion in
            self.client.perform(request) { (response: VerifiedHTTPResponse<CustomResponse>.Result) in
                completion(response)
            }
        }

        expect(result).toNot(beNil())
        expect(result).to(beFailure())

        let error = try XCTUnwrap(result?.error)
        switch error {
        case .decoding:
            break // correct error

        default:
            fail("Invalid error: \(error)")
        }
    }

    func testServerSide200s() {
        let request = HTTPRequest(method: .get, path: .mockPath)

        let responseData = "{\"message\": \"something is great up in the cloud\"}".asData

        stub(condition: isPath(request.path)) { _ in
            return HTTPStubsResponse(data: responseData,
                                     statusCode: .success,
                                     headers: nil)
        }

        let result = waitUntilValue { completion in
            self.client.perform(request) { (response: DataResponse) in
                completion(response)
            }
        }

        expect(result).toNot(beNil())
        expect(result).to(beSuccess())
        expect(result?.value?.body) == responseData
        self.logger.verifyMessageWasNotLogged("Queued request GET /v1/subscribers/identify for retry in 0.0 seconds.")
    }

    func testServerSide200WithETagInRequest() {
        let request = HTTPRequest(method: .get, path: .mockPath)
        let responseData = "{\"message\": \"something is great up in the cloud\"}".asData
        let eTag = "etag"
        let eTagValidationTime = Date(timeIntervalSince1970: 1234567)

        self.eTagManager.stubResponseEtag(eTag, validationTime: eTagValidationTime)

        stub(condition: isPath(request.path)) { request in
            expect(request.allHTTPHeaderFields?[ETagManager.eTagRequestHeader.rawValue]) == eTag
            expect(request.allHTTPHeaderFields?[ETagManager.eTagValidationTimeRequestHeader.rawValue])
            == eTagValidationTime.millisecondsSince1970.description

            return HTTPStubsResponse(data: responseData,
                                     statusCode: .success,
                                     headers: nil)
        }

        let result = waitUntilValue { completion in
            self.client.perform(request) { (response: DataResponse) in
                completion(response)
            }
        }

        expect(result).toNot(beNil())
        expect(result).to(beSuccess())
        expect(result?.value?.body) == responseData

        expect(self.eTagManager.invokedHTTPResultFromCacheOrBackend) == true
        expect(self.eTagManager.invokedHTTPResultFromCacheOrBackendCount) == 1
    }

    func testResponseDeserialization() throws {
        struct CustomResponse: Codable, Equatable, HTTPResponseBody {
            let message: String
        }

        let request = HTTPRequest(method: .get, path: .mockPath)

        let response = CustomResponse(message: "Something is great up in the cloud")
        let responseData = try JSONEncoder.default.encode(response)

        stub(condition: isPath(request.path)) { _ in
            return HTTPStubsResponse(data: responseData,
                                     statusCode: .success,
                                     headers: nil)
        }

        let result = waitUntilValue { completion in
            self.client.perform(request) { (response: VerifiedHTTPResponse<CustomResponse>.Result) in
                completion(response)
            }
        }

        expect(result).toNot(beNil())
        expect(result).to(beSuccess())
        expect(result?.value?.body) == response
        expect(result?.value?.httpStatusCode) == .success
    }

    func testCachedRequestsIncludeETagHeader() {
        let request = HTTPRequest(method: .post([:]), path: .mockPath)
        let eTag = "ETAG"

        let headerPresent: Atomic<Bool> = false

        self.eTagManager.stubResponseEtag(eTag)

        stub(condition: isPath(request.path)) { request in
            headerPresent.value = request.allHTTPHeaderFields?[ETagManager.eTagRequestHeader.rawValue] == eTag
            return .emptySuccessResponse()
        }

        waitUntil { completion in
            self.client.perform(request) { (_: DataResponse) in completion() }
        }

        expect(headerPresent.value) == true
        expect(self.eTagManager.invokedETagHeader) == true
    }

    func testNotCachedRequestsDontIncludeETagHeader() {
        let request = HTTPRequest(method: .post([:]), path: .health)
        let headerPresent: Atomic<Bool?> = nil

        stub(condition: isPath(request.path)) { request in
            headerPresent.value = request.allHTTPHeaderFields?.keys.contains(
                ETagManager.eTagRequestHeader.rawValue
            ) == true
            return .emptySuccessResponse()
        }

        waitUntil { completion in
            self.client.perform(request) { (_: DataResponse) in completion() }
        }

        expect(headerPresent.value) == false
        expect(self.eTagManager.invokedETagHeader) == false
    }

    func testAlwaysPassesClientVersion() {
        let request = HTTPRequest(method: .post([:]), path: .mockPath)

        let headerPresent: Atomic<Bool> = false

        let version = SystemInfo.appVersion

        stub(condition: hasHeaderNamed("X-Client-Version", value: version)) { _ in
            headerPresent.value = true
            return .emptySuccessResponse()
        }

        waitUntil { completion in
            self.client.perform(request) { (_: DataResponse) in completion() }
        }

        expect(headerPresent.value) == true
    }

    func testAlwaysPassesClientBuildVersion() throws {
        let request = HTTPRequest(method: .post([:]), path: .mockPath)

        let headerPresent: Atomic<Bool> = false

        let version = try XCTUnwrap(Bundle.main.infoDictionary!["CFBundleVersion"] as? String)

        stub(condition: hasHeaderNamed("X-Client-Build-Version", value: version )) { _ in
            headerPresent.value = true
            return .emptySuccessResponse()
        }

        waitUntil { completion in
            self.client.perform(request) { (_: DataResponse) in completion() }
        }

        expect(headerPresent.value) == true
    }

    func testAlwaysPassesClientBundleID() throws {
        let request = HTTPRequest(method: .post([:]), path: .mockPath)

        let headerPresent: Atomic<Bool> = false

        let bundleID = try XCTUnwrap(Bundle.main.bundleIdentifier)

        stub(condition: hasHeaderNamed("X-Client-Bundle-ID", value: bundleID)) { _ in
            headerPresent.value = true
            return .emptySuccessResponse()
        }

        waitUntil { completion in
            self.client.perform(request) { (_: DataResponse) in completion() }
        }

        expect(headerPresent.value) == true
    }

    func testPassesStoreKit2EnabledHeader() {
        let request = HTTPRequest(method: .post([:]), path: .mockPath)

        let headerPresent: Atomic<Bool> = false

        let enabled = self.systemInfo.storeKitVersion.isStoreKit2EnabledAndAvailable.description

        stub(condition: hasHeaderNamed("X-StoreKit2-Enabled",
                                       value: enabled)) { _ in
            headerPresent.value = true
            return .emptySuccessResponse()
        }

        waitUntil { completion in
            self.client.perform(request) { (_: DataResponse) in completion() }
        }

        expect(headerPresent.value) == true
    }

    func testPassesStoreKitVersionHeader() {
        let request = HTTPRequest(method: .post([:]), path: .mockPath)

        let headerPresent: Atomic<Bool> = false

        let version = self.systemInfo.storeKitVersion.effectiveVersion.debugDescription

        stub(condition: hasHeaderNamed("X-StoreKit-Version",
                                       value: version)) { _ in
            headerPresent.value = true
            return .emptySuccessResponse()
        }

        waitUntil { completion in
            self.client.perform(request) { (_: DataResponse) in completion() }
        }

        expect(headerPresent.value) == true
    }

    #if os(macOS) || targetEnvironment(macCatalyst)
    func testAlwaysPassesAppleDeviceIdentifierWhenIsSandbox() {
        let request = HTTPRequest(method: .get, path: .mockPath)

        let headerPresent: Atomic<Bool> = false
        systemInfo.stubbedIsSandbox = true

        let idfv = systemInfo.identifierForVendor!

        stub(condition: hasHeaderNamed("X-Apple-Device-Identifier", value: idfv )) { _ in
            headerPresent.value = true
            return .emptySuccessResponse()
        }

        waitUntil { completion in
            self.client.perform(request) { (_: DataResponse) in completion() }
        }

        expect(headerPresent.value) == true
    }

    func testAppleDeviceIdentifierNilWhenIsNotSandboxInMacOS() {
        self.systemInfo.stubbedIsSandbox = false

        expect(self.systemInfo.identifierForVendor).to(beNil())
    }

    #else

    func testAlwaysPassesAppleDeviceIdentifier() throws {
        let request = HTTPRequest(method: .post([:]), path: .mockPath)

        let headerPresent: Atomic<Bool> = false

        let idfv = try XCTUnwrap(self.systemInfo.identifierForVendor)

        stub(condition: hasHeaderNamed("X-Apple-Device-Identifier", value: idfv )) { _ in
            headerPresent.value = true
            return .emptySuccessResponse()
        }

        waitUntil { completion in
            self.client.perform(request) { (_: DataResponse) in completion() }
        }

        expect(headerPresent.value) == true
    }
    #endif

    func testDefaultsPlatformFlavorToNative() {
        let request = HTTPRequest(method: .post([:]), path: .mockPath)

        let headerPresent: Atomic<Bool> = false

        stub(condition: hasHeaderNamed("X-Platform-Flavor", value: "native")) { _ in
            headerPresent.value = true
            return .emptySuccessResponse()
        }

        waitUntil { completion in
            self.client.perform(request) { (_: DataResponse) in completion() }
        }

        expect(headerPresent.value) == true
    }

    func testPassesPlatformFlavorHeader() {
        let request = HTTPRequest(method: .post([:]), path: .mockPath)

        let headerPresent: Atomic<Bool> = false

        stub(condition: hasHeaderNamed("X-Platform-Flavor", value: "react-native")) { _ in
            headerPresent.value = true
            return .emptySuccessResponse()
        }
        let platformInfo = Purchases.PlatformInfo(flavor: "react-native", version: "3.2.1")
        let systemInfo = SystemInfo(platformInfo: platformInfo,
                                    finishTransactions: true)

        self.client = self.createClient(systemInfo)

        waitUntil { completion in
            self.client.perform(request) { (_: DataResponse) in completion() }
        }

        expect(headerPresent.value) == true
    }

    func testPassesPlatformDeviceHeader() {
        let request = HTTPRequest(method: .post([:]), path: .mockPath)

        let headerPresent: Atomic<Bool> = false

        stub(condition: hasHeaderNamed("X-Platform-Device", value: SystemInfo.deviceVersion)) { _ in
            headerPresent.value = true
            return .emptySuccessResponse()
        }

        waitUntil { completion in
            self.client.perform(request) { (_: DataResponse) in completion() }
        }

        expect(headerPresent.value) == true
    }

    func testPassesPlatformFlavorVersionHeader() {
        let request = HTTPRequest(method: .post([:]), path: .mockPath)

        let headerPresent: Atomic<Bool> = false

        stub(condition: hasHeaderNamed("X-Platform-Flavor-Version", value: "1.2.3")) { _ in
            headerPresent.value = true
            return .emptySuccessResponse()
        }
        let platformInfo = Purchases.PlatformInfo(flavor: "react-native", version: "1.2.3")
        let systemInfo = SystemInfo(platformInfo: platformInfo, finishTransactions: true)
        self.client = self.createClient(systemInfo)

        waitUntil { completion in
            self.client.perform(request) { (_: DataResponse) in completion() }
        }

        expect(headerPresent.value) == true
    }

    func testPassesObserverModeHeaderCorrectlyWhenEnabled() {
        let request = HTTPRequest(method: .post([:]), path: .mockPath)

        let headerPresent: Atomic<Bool> = false

        stub(condition: hasHeaderNamed("X-Observer-Mode-Enabled", value: "false")) { _ in
            headerPresent.value = true
            return .emptySuccessResponse()
        }
        self.client = self.createClient(SystemInfo(platformInfo: nil, finishTransactions: true))

        waitUntil { completion in
            self.client.perform(request) { (_: DataResponse) in completion() }
        }

        expect(headerPresent.value) == true
    }

    func testPassesUIPreviewModeHeaderCorrectlyWhenEnabled() {
        let headerName = "X-UI-Preview-Mode"
        let systemInfo = SystemInfo(platformInfo: nil,
                                    finishTransactions: true,
                                    dangerousSettings: .init(uiPreviewMode: true))
        self.client = self.createClient(systemInfo)

        let header: Atomic<String?> = nil

        let request = HTTPRequest(method: .post([:]), path: .mockPath)

        stub(condition: hasHeaderNamed(headerName)) { request in
            header.value = request.value(forHTTPHeaderField: headerName)
            return .emptySuccessResponse()
        }

        waitUntil { completion in
            self.client.perform(request) { (_: EmptyResponse) in completion() }
        }

        expect(header.value) == "true"
    }

    func testDoesNotPassUIPreviewModeHeaderWhenDisabled() {
        let headerName = "X-UI-Preview-Mode"
        let systemInfo = SystemInfo(platformInfo: nil,
                                    finishTransactions: true,
                                    dangerousSettings: .init(uiPreviewMode: false))
        self.client = self.createClient(systemInfo)

        let header: Atomic<String?> = nil

        let request = HTTPRequest(method: .post([:]), path: .mockPath)

        stub(condition: isPath(request.path)) { request in
            header.value = request.value(forHTTPHeaderField: headerName)
            return .emptySuccessResponse()
        }

        waitUntil { completion in
            self.client.perform(request) { (_: EmptyResponse) in completion() }
        }

        expect(header.value) == nil
    }

    func testRequestsWithCustomEntitlementsSendHeader() {
        self.client = self.createClient(MockSystemInfo(finishTransactions: true, customEntitlementsComputation: true))

        let request = HTTPRequest(method: .post([:]), path: .mockPath)

        var headerPresent = false

        stub(condition: isPath(request.path)) { request in
            let headers =  request.allHTTPHeaderFields ?? [:]
            headerPresent = headers["X-Custom-Entitlements-Computation"] != nil
                && headers["X-Custom-Entitlements-Computation"] == "true"
            return .emptySuccessResponse()
        }

        waitUntil { completion in
            self.client.perform(request) { (_: DataResponse) in completion() }
        }

        expect(headerPresent) == true
    }

    func testRequestsWithoutCustomEntitlementsDoNotSendHeader() {
        self.client = self.createClient(MockSystemInfo(finishTransactions: true, customEntitlementsComputation: false))

        let request = HTTPRequest(method: .post([:]), path: .mockPath)

        var headerPresent = true

        stub(condition: isPath(request.path)) { request in
            let headers =  request.allHTTPHeaderFields ?? [:]
            headerPresent = headers["X-Custom-Entitlements-Computation"] != nil
            return .emptySuccessResponse()
        }

        waitUntil { completion in
            self.client.perform(request) { (_: DataResponse) in completion() }
        }

        expect(headerPresent) == false
    }

    func testPassesObserverModeHeaderCorrectlyWhenDisabled() {
        let request = HTTPRequest(method: .post([:]), path: .mockPath)

        let headerPresent: Atomic<Bool> = false

        stub(condition: hasHeaderNamed("X-Observer-Mode-Enabled", value: "true")) { _ in
            headerPresent.value = true
            return .emptySuccessResponse()
        }
        self.client = self.createClient(SystemInfo(platformInfo: nil, finishTransactions: false))

        waitUntil { completion in
            self.client.perform(request) { (_: DataResponse) in completion() }
        }

        expect(headerPresent.value) == true
    }

    func testPerformSerialRequestPerformsAllRequestsInTheCorrectOrder() {
        let path: HTTPRequest.Path = .mockPath

        let completionCallCount: Atomic<Int> = .init(0)

        stub(condition: isPath(path)) { request in
            let requestNumber = Self.extractRequestNumber(from: request)
            expect(requestNumber) == completionCallCount.value

            let json = "{\"message\": \"something is great up in the cloud\"}"
            return HTTPStubsResponse(data: json.asData,
                                     statusCode: .success,
                                     headers: nil)
                .responseTime(0.003)
        }

        let serialRequests = 10
        for requestNumber in 0..<serialRequests {
            let expectation = self.expectation(description: "Request \(requestNumber)")

            client.perform(.init(method: .requestNumber(requestNumber), path: path)) { (_: DataResponse) in
                completionCallCount.value += 1
                expectation.fulfill()
            }
        }

        self.waitForExpectations(timeout: defaultTimeout.seconds)
        expect(completionCallCount.value) == serialRequests
    }

    func testPerformSerialRequestWaitsUntilFirstRequestIsDoneBeforeStartingSecond() {
        let path: HTTPRequest.Path = .mockPath

        let firstRequestFinished: Atomic<Bool> = false
        let secondRequestFinished: Atomic<Bool> = false

        stub(condition: isPath(path)) { request in
            usleep(30)
            let requestNumber = Self.extractRequestNumber(from: request)
            if requestNumber == 2 {
                expect(firstRequestFinished.value) == true
            }

            let json = "{\"message\": \"something is great up in the cloud\"}"
            return HTTPStubsResponse(data: json.data(using: String.Encoding.utf8)!,
                                     statusCode: .success,
                                     headers: nil)
                .responseTime(0.1)
        }

        let expectations = [
            self.expectation(description: "Request 1"),
            self.expectation(description: "Request 2")
        ]

        self.client.perform(.init(method: .requestNumber(1), path: path)) { (_: DataResponse) in
            firstRequestFinished.value = true
            expectations[0].fulfill()
        }

        self.client.perform(.init(method: .requestNumber(2), path: path)) { (_: DataResponse) in
            secondRequestFinished.value = true
            expectations[1].fulfill()
        }

        self.waitForExpectations(timeout: defaultTimeout.seconds)

        expect(firstRequestFinished.value) == true
        expect(secondRequestFinished.value) == true
    }

    func testPerformSerialRequestWaitsUntilRequestsAreDoneBeforeStartingNext() {
        let path: HTTPRequest.Path = .mockPath

        let firstRequestFinished: Atomic<Bool> = false
        let secondRequestFinished: Atomic<Bool> = false
        let thirdRequestFinished: Atomic<Bool> = false

        stub(condition: isPath(path)) { request in
            let requestNumber = Self.extractRequestNumber(from: request)
            var responseTime = 0.05
            if requestNumber == 1 {
                expect(secondRequestFinished.value) == false
                expect(thirdRequestFinished.value) == false
            } else if requestNumber == 2 {
                expect(firstRequestFinished.value) == true
                expect(thirdRequestFinished.value) == false
                responseTime = 0.03
            } else if requestNumber == 3 {
                expect(firstRequestFinished.value) == true
                expect(secondRequestFinished.value) == true
                responseTime = 0.01
            }

            let json = "{\"message\": \"something is great up in the cloud\"}"
            return HTTPStubsResponse(data: json.asData,
                                     statusCode: .success,
                                     headers: nil)
                .responseTime(responseTime)
        }

        let expectations = [
            self.expectation(description: "Request 1"),
            self.expectation(description: "Request 2"),
            self.expectation(description: "Request 3")
        ]

        self.client.perform(.init(method: .requestNumber(1), path: path)) { (_: DataResponse) in
            firstRequestFinished.value = true
            expectations[0].fulfill()
        }

        self.client.perform(.init(method: .requestNumber(2), path: path)) { (_: DataResponse) in
            secondRequestFinished.value = true
            expectations[1].fulfill()
        }

        self.client.perform(.init(method: .requestNumber(3), path: path)) { (_: DataResponse) in
            thirdRequestFinished.value = true
            expectations[2].fulfill()
        }

        self.waitForExpectations(timeout: defaultTimeout.seconds)

        expect(firstRequestFinished.value) == true
        expect(secondRequestFinished.value) == true
        expect(thirdRequestFinished.value) == true
    }

    func testPerformRequestExitsWithErrorIfBodyCouldntBeParsedIntoJSON() throws {
        let response = waitUntilValue { completion in
            self.client.perform(.init(method: .invalidBody(), path: .mockPath)) { (result: DataResponse) in
                completion(result)
            }
        }

        let error = try XCTUnwrap(response?.error)
        expect(error) == .unableToCreateRequest(HTTPRequest.Path.mockPath)
    }

    func testPerformRequestDoesntPerformRequestIfBodyCouldntBeParsedIntoJSON() {
        let path: HTTPRequest.Path = .mockPath

        let httpCallMade: Atomic<Bool> = false

        stub(condition: isPath(path)) { _ in
            httpCallMade.value = true
            return .emptySuccessResponse()
        }

        waitUntil { completion in
            self.client.perform(.init(method: .invalidBody(), path: path)) { (_: DataResponse) in
                completion()
            }
        }

        expect(httpCallMade.value) == false
    }

    func testRequestIsRetriedIfResponseFromETagManagerIsNil() {
        let path: HTTPRequest.Path = .mockPath

        let requests: Atomic<Int> = .init(0)

        stub(condition: isPath(path)) { [eTagManager = self.eTagManager!] _ in
            defer { requests.value += 1 }

            if requests.value > 0 {
                eTagManager.shouldReturnResultFromBackend = true
            }

            return .emptySuccessResponse()
        }

        self.eTagManager.shouldReturnResultFromBackend = false
        self.eTagManager.stubbedHTTPResultFromCacheOrBackendResult = nil

        let result: DataResponse? = waitUntilValue { completion in
            self.client.perform(.init(method: .get, path: path)) {
                completion($0)
            }
        }

        expect(result).to(beSuccess())
        expect(requests.value) == 2
    }

    func testGetsResponseFromETagManagerWhenStatusCodeIsNotModified() throws {
        let path: HTTPRequest.Path = .mockPath

        let mockedCachedResponse = try JSONSerialization.data(withJSONObject: [
            "test": "data"
        ])
        let eTag = "tag"
        let requestDate = Date().addingTimeInterval(-1000000)

        let headers: [String: String] = [
            HTTPClient.ResponseHeader.contentType.rawValue: "application/json",
            HTTPClient.ResponseHeader.signature.rawValue: UUID().uuidString,
            HTTPClient.ResponseHeader.requestDate.rawValue: String(requestDate.millisecondsSince1970)
        ]

        self.eTagManager.stubResponseEtag(eTag)
        self.eTagManager.shouldReturnResultFromBackend = false
        self.eTagManager.stubbedHTTPResultFromCacheOrBackendResult = .init(
            httpStatusCode: .success,
            responseHeaders: headers,
            body: mockedCachedResponse,
            verificationResult: .verified
        )

        stub(condition: isPath(path)) { response in
            expect(response.allHTTPHeaderFields?[ETagManager.eTagRequestHeader.rawValue]) == eTag

            return .init(data: Data(),
                         statusCode: .notModified,
                         headers: headers)
        }

        let response: DataResponse? = waitUntilValue { completion in
            self.client.perform(.init(method: .get, path: path)) { (result: DataResponse) in
                completion(result)
            }
        }

        expect(response).toNot(beNil())
        expect(response?.value?.httpStatusCode) == .success
        expect(response?.value?.body) == mockedCachedResponse
        expect(response?.value?.requestDate).to(beCloseToDate(requestDate))
        expect(response?.value?.verificationResult) == .notRequested
        expect(response?.value?.responseHeaders.keys).to(contain(Array(headers.keys.map(AnyHashable.init))))

        expect(self.eTagManager.invokedETagHeaderParametersList).to(haveCount(1))
    }

    func testDNSCheckerIsCalledWhenGETRequestFailedWithUnknownError() {
        let path: HTTPRequest.Path = .mockPath

        let error = NSError(domain: NSURLErrorDomain, code: NSURLErrorUnknown, userInfo: nil)
        MockDNSChecker.stubbedIsBlockedAPIErrorResult.value = false

        stub(condition: isPath(path)) { _ in
            let response = HTTPStubsResponse.emptySuccessResponse()
            response.error = error
            return response
        }

        waitUntil { completion in
            self.client.perform(.init(method: .get, path: path)) { (_: DataResponse) in
                completion()
            }
        }

        expect(MockDNSChecker.invokedErrorWithBlockedHostFromError.value) == true
        expect(MockDNSChecker.invokedIsBlockedAPIError.value) == false
    }

    func testDNSCheckerIsCalledWhenPOSTRequestFailedWithUnknownError() {
        let path: HTTPRequest.Path = .mockPath

        let error = NSError(domain: NSURLErrorDomain, code: NSURLErrorUnknown, userInfo: nil)
        MockDNSChecker.stubbedIsBlockedAPIErrorResult.value = false

        stub(condition: isPath(path)) { _ in
            let response = HTTPStubsResponse.emptySuccessResponse()
            response.error = error
            return response
        }

        waitUntil { completion in
            self.client.perform(.init(method: .post([:]), path: path)) { (_: DataResponse) in
                completion()
            }
        }

        expect(MockDNSChecker.invokedErrorWithBlockedHostFromError.value) == true
        expect(MockDNSChecker.invokedIsBlockedAPIError.value) == false
    }

    func testDNSCheckedIsCalledWhenPOSTRequestFailedWithDNSError() {
        let path: HTTPRequest.Path = .mockPath

        let fakeSubscribersURL = URL(string: "https://0.0.0.0/subscribers")!
        let userInfo: [String: Any] = [NSURLErrorFailingURLErrorKey: fakeSubscribersURL]
        let nsErrorWithUserInfo = NSError(domain: NSURLErrorDomain,
                                          code: NSURLErrorCannotConnectToHost,
                                          userInfo: userInfo as [String: Any])
        MockDNSChecker.stubbedIsBlockedAPIErrorResult.value = true

        stub(condition: isPath(path)) { _ in
            let response = HTTPStubsResponse.emptySuccessResponse()
            response.error = nsErrorWithUserInfo
            return response
        }

        waitUntil { completion in
            self.client.perform(.init(method: .post([:]), path: path)) { (_: DataResponse) in
                completion()
            }
        }

        expect(MockDNSChecker.invokedErrorWithBlockedHostFromError.value) == true
        expect(MockDNSChecker.invokedIsBlockedAPIError.value) == false
    }

    func testDNSCheckedIsCalledWhenGETRequestFailedWithDNSError() {
        let path: HTTPRequest.Path = .mockPath

        let fakeSubscribersURL = URL(string: "https://0.0.0.0/subscribers")!
        let userInfo: [String: Any] = [NSURLErrorFailingURLErrorKey: fakeSubscribersURL]
        let nsErrorWithUserInfo = NSError(domain: NSURLErrorDomain,
                                          code: NSURLErrorCannotConnectToHost,
                                          userInfo: userInfo as [String: Any])
        MockDNSChecker.stubbedIsBlockedAPIErrorResult.value = true

        stub(condition: isPath(path)) { _ in
            let response = HTTPStubsResponse.emptySuccessResponse()
            response.error = nsErrorWithUserInfo
            return response
        }
        waitUntil { completion in
            self.client.perform(.init(method: .get, path: path)) { (_: DataResponse) in
                completion()
            }
        }

        expect(MockDNSChecker.invokedErrorWithBlockedHostFromError.value) == true
        expect(MockDNSChecker.invokedIsBlockedAPIError.value) == false
    }

    func testOfflineConnectionError() {
        let path: HTTPRequest.Path = .mockPath

        let error = NSError(domain: NSURLErrorDomain, code: NSURLErrorNotConnectedToInternet)
        let expectedError: NetworkError = .networkError(error)

        stub(condition: isPath(path)) { _ in
            let response = HTTPStubsResponse.emptySuccessResponse()
            response.error = error
            return response
        }

        let obtainedError: NetworkError? = waitUntilValue { completion in
            self.client.perform(.init(method: .get, path: path)) { (result: DataResponse) in
                completion(result.error)
            }
        }

        // Can't compare the errors directly because `obtainedError` has additional userInfo.
        expect(obtainedError?.asPurchasesError)
            .to(matchError(expectedError.asPurchasesError))
    }

    func testErrorIsLoggedAndReturnsDNSErrorWhenGETRequestFailedWithDNSError() {
        let path: HTTPRequest.Path = .mockPath

        let error = NSError(domain: NSURLErrorDomain, code: NSURLErrorUnknown, userInfo: nil)
        let expectedDNSError: NetworkError = .dnsError(
            failedURL: URL(string: "https://0.0.0.0/subscribers")!,
            resolvedHost: "0.0.0.0"
        )
        MockDNSChecker.stubbedIsBlockedAPIErrorResult.value = true
        MockDNSChecker.stubbedErrorWithBlockedHostFromErrorResult.value = expectedDNSError
        let expectedMessage = "\(LogIntent.rcError.prefix) \(expectedDNSError.description)"

        stub(condition: isPath(path)) { _ in
            let response = HTTPStubsResponse.emptySuccessResponse()
            response.error = error
            return response
        }

        let obtainedError: NetworkError? = waitUntilValue { completion in
            self.client.perform(.init(method: .get, path: path)) { (result: DataResponse) in
                completion(result.error)
            }
        }

        expect(MockDNSChecker.invokedErrorWithBlockedHostFromError.value) == true
        expect(MockDNSChecker.invokedIsBlockedAPIError.value) == false
        expect(obtainedError) == expectedDNSError
        expect(self.logger.messages.map(\.message))
            .to(contain(expectedMessage))
    }

    func testErrorIsntLoggedWhenGETRequestFailedWithUnknownError() {
        let path: HTTPRequest.Path = .mockPath

        let error = NSError(domain: NSURLErrorDomain, code: NSURLErrorUnknown, userInfo: nil)
        let unexpectedDNSError: NetworkError = .dnsError(
            failedURL: URL(string: "https://0.0.0.0/subscribers")!,
            resolvedHost: "0.0.0.0"
        )
        MockDNSChecker.stubbedIsBlockedAPIErrorResult.value = false

        stub(condition: isPath(path)) { _ in
            let response = HTTPStubsResponse.emptySuccessResponse()
            response.error = error
            return response
        }

        waitUntil { completion in
            self.client.perform(.init(method: .get, path: path)) { (_: DataResponse) in
                completion()
            }
        }

        expect(MockDNSChecker.invokedErrorWithBlockedHostFromError.value) == true
        expect(MockDNSChecker.invokedIsBlockedAPIError.value) == false
        expect(self.logger.messages.map(\.message))
            .toNot(contain(unexpectedDNSError.description))
    }

    func testResponseFromServerUpdatesRequestDate() throws {
        let path: HTTPRequest.Path = .mockPath
        let mockedResponse = BodyWithDate(data: "test", requestDate: Date().addingTimeInterval(-3000000))
        let encodedResponse = try mockedResponse.jsonEncodedData
        let requestDate = Date().addingTimeInterval(-100000)

        stub(condition: isPath(path)) { _ in
            return HTTPStubsResponse(
                data: encodedResponse,
                statusCode: .success,
                headers: [
                    HTTPClient.ResponseHeader.requestDate.rawValue: String(requestDate.millisecondsSince1970)
                ]
            )
        }

        let response: BodyWithDateResponse? = waitUntilValue { completion in
            self.client.perform(.init(method: .get, path: path), completionHandler: completion)
        }

        expect(response).to(beSuccess())
        expect(response?.value?.body.requestDate).to(beCloseTo(requestDate, within: 1))
    }

    func testCachedResponseUpdatesRequestDate() throws {
        let path: HTTPRequest.Path = .mockPath
        let eTag = "etag"
        let mockedResponse = BodyWithDate(data: "test", requestDate: Date().addingTimeInterval(-30000000))
        let encodedResponse = try mockedResponse.jsonEncodedData
        let requestDate = Date().addingTimeInterval(-1000000)

        self.eTagManager.stubResponseEtag(eTag)
        self.eTagManager.shouldReturnResultFromBackend = false
        self.eTagManager.stubbedHTTPResultFromCacheOrBackendResult = .init(
            httpStatusCode: .success,
            responseHeaders: [:],
            body: encodedResponse,
            requestDate: requestDate,
            verificationResult: .notRequested
        )

        stub(condition: isPath(path)) { _ in
            return HTTPStubsResponse(
                data: .init(),
                statusCode: .notModified,
                headers: [
                    HTTPClient.ResponseHeader.requestDate.rawValue: String(requestDate.millisecondsSince1970)
                ]
            )
        }

        let response: BodyWithDateResponse? = waitUntilValue { completion in
            self.client.perform(.init(method: .get, path: path), completionHandler: completion)
        }

        expect(response).to(beSuccess())
        expect(response?.value?.body.requestDate).to(beCloseTo(requestDate, within: 1))
        expect(response?.value?.verificationResult) == .notRequested

        expect(self.eTagManager.invokedETagHeaderParametersList).to(haveCount(1))
    }

    func testFakeServerErrors() {
        let path: HTTPRequest.Path = .mockPath

        stub(condition: isPath(path)) { _ in
            fail("Should not perform request")
            return .emptySuccessResponse()
        }

        self.client = self.createClient(
            .init(
                platformInfo: nil,
                finishTransactions: false,
                dangerousSettings: .init(
                    autoSyncPurchases: true,
                    internalSettings: DangerousSettings.Internal(forceServerErrors: true)
                )
            )
        )

        let response: BodyWithDateResponse? = waitUntilValue { completion in
            self.client.perform(.init(method: .get, path: path), completionHandler: completion)
        }

        expect(response).to(beFailure())
        expect(response?.error).to(matchError(NetworkError.errorResponse(
            ErrorResponse(code: .internalServerError,
                          originalCode: BackendErrorCode.unknownBackendError.rawValue),
            .internalServerError)
        ))
    }

    func testRedirectIsLogged() throws {
        // Task delegate is only available after iOS 15.
        try AvailabilityChecks.iOS15APIAvailableOrSkipTest()

        let pathA: HTTPRequest.Path = .logIn
        let pathB: HTTPRequest.Path = .health

        let responseData = "{\"message\": \"something is great up in the cloud\"}".asData

        stub(condition: isPath(pathA)) { _ in
            return HTTPStubsResponse(
                data: .init(),
                statusCode: .temporaryRedirect,
                headers: [
                    HTTPClient.ResponseHeader.location.rawValue: pathB.url!.absoluteString
                ]
            )
        }
        stub(condition: isPath(pathB)) { _ in
            return HTTPStubsResponse(
                data: responseData,
                statusCode: .success,
                headers: nil
            )
        }

        let response: DataResponse? = waitUntilValue { completion in
            self.client.perform(.init(method: .get, path: pathA), completionHandler: completion)
        }

        expect(response).to(beSuccess())
        expect(response?.value?.body) == responseData

        self.logger.verifyMessageWasLogged(
            "Performing redirect from '\(pathA.url!.absoluteString)' to '\(pathB.url!.absoluteString)'",
            level: .debug
        )
    }

    func testNormalResponsesAreNotDetectedAsLoadSheddder() throws {
        let path: HTTPRequest.Path = .logIn

        stub(condition: isPath(path)) { _ in
            return HTTPStubsResponse(
                data: .init(),
                statusCode: .success,
                headers: [:]
            )
        }

        let response: DataResponse? = waitUntilValue { completion in
            self.client.perform(.init(method: .get, path: path), completionHandler: completion)
        }
        expect(response).to(beSuccess())

        self.logger.verifyMessageWasNotLogged(Strings.network.request_handled_by_load_shedder(path))
    }

    func testLoadShedderResponsesAreLogged() throws {
        let path: HTTPRequest.Path = .logIn

        stub(condition: isPath(path)) { _ in
            return HTTPStubsResponse(
                data: .init(),
                statusCode: .success,
                headers: [
                    HTTPClient.ResponseHeader.isLoadShedder.rawValue: "true"
                ]
            )
        }

        let response: DataResponse? = waitUntilValue { completion in
            self.client.perform(.init(method: .get, path: path), completionHandler: completion)
        }
        expect(response).to(beSuccess())

        self.logger.verifyMessageWasLogged(
            Strings.network.request_handled_by_load_shedder(path),
            level: .debug
        )
    }

    // - MARK: Diagnostics http request performed tracking

    @available(iOS 15.0, tvOS 15.0, macOS 12.0, watchOS 8.0, *)
    func testDiagnosticsHttpRequestPerformedTrackedOnSuccess() throws {
        try AvailabilityChecks.iOS15APIAvailableOrSkipTest()

        let request = HTTPRequest(method: .get, path: .mockPath)

        stub(condition: isPath(request.path)) { _ in
            return .emptySuccessResponse()
        }

        waitUntil { completion in
            self.client.perform(request) { (_: EmptyResponse) in completion() }
        }

        // swiftlint:disable:next force_cast
        let mockDiagnosticsTracker = self.diagnosticsTracker as! MockDiagnosticsTracker
        expect(mockDiagnosticsTracker.trackedHttpRequestPerformedParams.value.count).toEventually(equal(1))
        guard let trackedParams = mockDiagnosticsTracker.trackedHttpRequestPerformedParams.value.first else {
            fail("Should have at least one call to tracked diagnostics")
            return
        }
        expect(trackedParams).to(matchTrackParams((
            "log_in",
            -1, // Any
            true,
            200,
            nil,
            .backend,
            .notRequested
        )))
    }

    @available(iOS 15.0, tvOS 15.0, macOS 12.0, watchOS 8.0, *)
    func testDiagnosticsHttpRequestPerformedTrackedOnError() throws {
        try AvailabilityChecks.iOS15APIAvailableOrSkipTest()

        let request = HTTPRequest(method: .get, path: .mockPath)

        waitUntil { completion in
            self.client.perform(request) { (_: EmptyResponse) in completion() }
        }

        // swiftlint:disable:next force_cast
        let mockDiagnosticsTracker = self.diagnosticsTracker as! MockDiagnosticsTracker
        expect(mockDiagnosticsTracker.trackedHttpRequestPerformedParams.value.count).toEventually(equal(1))
        guard let trackedParams = mockDiagnosticsTracker.trackedHttpRequestPerformedParams.value.first else {
            fail("Should have at least one call to tracked diagnostics")
            return
        }
        expect(trackedParams).to(matchTrackParams((
            "log_in",
            -1, // Any
            false,
            401,
            7225,
            nil,
            .notRequested
        )))
    }

}

// MARK: - HttpClient.Request Tests
extension HTTPClientTests {
    func testNewRequestHasNoRetries() {
        let request = buildEmptyRequest(isRetryable: true)

        expect(request.retried).to(beFalse())
        expect(request.retryCount).to(equal(0))
    }

    func testRetryingRequestIncrementsRetryCount() {
        let request = buildEmptyRequest(isRetryable: true)

        let retriedRequest = request.retriedRequest()
        let secondRetriedRequest = retriedRequest.retriedRequest()

        expect(retriedRequest.retried).to(beTrue())
        expect(retriedRequest.retryCount).to(equal(1))

        expect(secondRetriedRequest.retried).to(beTrue())
        expect(secondRetriedRequest.retryCount).to(equal(2))
    }

    private func buildEmptyRequest(
        isRetryable: Bool
    ) -> HTTPClient.Request {
        let completionHandler: HTTPClient.Completion<CustomerInfo> = { _ in return }

        let request: HTTPClient.Request = .init(
            httpRequest: .init(method: .get, path: .getCustomerInfo(appUserID: "abc123"), isRetryable: isRetryable),
            authHeaders: .init(),
            defaultHeaders: .init(),
            verificationMode: .default,
            internalSettings: DangerousSettings.Internal.default,
            completionHandler: completionHandler
        )

        return request
    }
}

// MARK: - HttpClient Retry Tests
extension HTTPClientTests {

    func testOnlyRetriesProvidedHTTPStatusCodesIfIsRetryableHeaderMissing() {
        expect(self.client.isResponseRetryable(
            HTTPURLResponse(
                url: URL(string: "https://api.revenuecat.com/v1/receipts")!,
                statusCode: HTTPStatusCode.tooManyRequests.rawValue,
                httpVersion: nil,
                headerFields: nil
            )!
        )).to(beTrue())
        expect(self.client.isResponseRetryable(
            HTTPURLResponse(
                url: URL(string: "https://api.revenuecat.com/v1/receipts")!,
                statusCode: HTTPStatusCode.invalidRequest.rawValue,
                httpVersion: nil,
                headerFields: nil
            )!
        )).to(beFalse())
    }

    func testWontRetryIfIsRetryableHeaderFalse() {
        expect(self.client.isResponseRetryable(
            HTTPURLResponse(
                url: URL(string: "https://api.revenuecat.com/v1/receipts")!,
                statusCode: HTTPStatusCode.tooManyRequests.rawValue,
                httpVersion: nil,
                headerFields: [
                    HTTPClient.ResponseHeader.isRetryable.rawValue: "false"
                ]
            )!
        )).to(beFalse())

        expect(self.client.isResponseRetryable(
            HTTPURLResponse(
                url: URL(string: "https://api.revenuecat.com/v1/receipts")!,
                statusCode: HTTPStatusCode.tooManyRequests.rawValue,
                httpVersion: nil,
                headerFields: [
                    HTTPClient.ResponseHeader.isRetryable.rawValue: "False"
                ]
            )!
        )).to(beFalse())

        expect(self.client.isResponseRetryable(
            HTTPURLResponse(
                url: URL(string: "https://api.revenuecat.com/v1/receipts")!,
                statusCode: HTTPStatusCode.tooManyRequests.rawValue,
                httpVersion: nil,
                headerFields: [
                    HTTPClient.ResponseHeader.isRetryable.rawValue: "FALSE"
                ]
            )!
        )).to(beFalse())
    }

    func testWillRetryIfIsRetryableHeaderTrue() {
        expect(self.client.isResponseRetryable(
            HTTPURLResponse(
                url: URL(string: "https://api.revenuecat.com/v1/receipts")!,
                statusCode: HTTPStatusCode.tooManyRequests.rawValue,
                httpVersion: nil,
                headerFields: [
                    HTTPClient.ResponseHeader.isRetryable.rawValue: "true"
                ]
            )!
        )).to(beTrue())

        expect(self.client.isResponseRetryable(
            HTTPURLResponse(
                url: URL(string: "https://api.revenuecat.com/v1/receipts")!,
                statusCode: HTTPStatusCode.tooManyRequests.rawValue,
                httpVersion: nil,
                headerFields: [
                    HTTPClient.ResponseHeader.isRetryable.rawValue: "True"
                ]
            )!
        )).to(beTrue())

        expect(self.client.isResponseRetryable(
            HTTPURLResponse(
                url: URL(string: "https://api.revenuecat.com/v1/receipts")!,
                statusCode: HTTPStatusCode.tooManyRequests.rawValue,
                httpVersion: nil,
                headerFields: [
                    HTTPClient.ResponseHeader.isRetryable.rawValue: "TRUE"
                ]
            )!
        )).to(beTrue())
    }

    func testWillNotRetryIfIsRetryableHeaderTrueButStatusCodeIsNotRetryable() {
        expect(self.client.isResponseRetryable(
            HTTPURLResponse(
                url: URL(string: "https://api.revenuecat.com/v1/receipts")!,
                statusCode: HTTPStatusCode.success.rawValue,
                httpVersion: nil,
                headerFields: [
                    HTTPClient.ResponseHeader.isRetryable.rawValue: "true"
                ]
            )!
        )).to(beFalse())
    }

    // Backoff Time Tests
    func testUsesNoBackoffIfFirstRetryAndNoETagPresent() {
        var httpURLResponse = HTTPURLResponse(
            url: URL(string: "https://api.revenuecat.com/v1/receipts")!,
            statusCode: HTTPStatusCode.tooManyRequests.rawValue,
            httpVersion: nil,
            headerFields: [:]
        )!

        var backoffPeriod = self.client.calculateRetryBackoffTime(forResponse: httpURLResponse, retryCount: 1)
        expect(backoffPeriod).to(equal(TimeInterval(0)))

        httpURLResponse = HTTPURLResponse(
            url: URL(string: "https://api.revenuecat.com/v1/receipts")!,
            statusCode: HTTPStatusCode.tooManyRequests.rawValue,
            httpVersion: nil,
            headerFields: [HTTPClient.ResponseHeader.eTag.rawValue: ""]
        )!

        backoffPeriod = self.client.calculateRetryBackoffTime(forResponse: httpURLResponse, retryCount: 1)
        expect(backoffPeriod).to(equal(TimeInterval(0)))
    }

    func testUsesBackoffIfFirstRetryAndETagPresent() {
        var httpURLResponse = HTTPURLResponse(
            url: URL(string: "https://api.revenuecat.com/v1/receipts")!,
            statusCode: HTTPStatusCode.tooManyRequests.rawValue,
            httpVersion: nil,
            headerFields: [:]
        )!

        var backoffPeriod = self.client.calculateRetryBackoffTime(forResponse: httpURLResponse, retryCount: 1)
        expect(backoffPeriod).to(equal(TimeInterval(0)))

        httpURLResponse = HTTPURLResponse(
            url: URL(string: "https://api.revenuecat.com/v1/receipts")!,
            statusCode: HTTPStatusCode.tooManyRequests.rawValue,
            httpVersion: nil,
            headerFields: [HTTPClient.ResponseHeader.eTag.rawValue: "some-etag-value"]
        )!

        backoffPeriod = self.client.calculateRetryBackoffTime(forResponse: httpURLResponse, retryCount: 1)
        expect(backoffPeriod).to(equal(TimeInterval(0)))
    }

    func testUsesServerProvidedBackoffIfPresent() {
        let retryAfterSeconds = 100

        var httpURLResponse = HTTPURLResponse(
            url: URL(string: "https://api.revenuecat.com/v1/receipts")!,
            statusCode: HTTPStatusCode.tooManyRequests.rawValue,
            httpVersion: nil,
            headerFields: [
                HTTPClient.ResponseHeader.retryAfter.rawValue: "\(retryAfterSeconds)"
            ]
        )!

        var backoffPeriod = self.client.calculateRetryBackoffTime(forResponse: httpURLResponse, retryCount: 2)
        expect(backoffPeriod).to(equal(TimeInterval(retryAfterSeconds)))

        let retryAfterSecondsDecimal = 10.5
        httpURLResponse = HTTPURLResponse(
            url: URL(string: "https://api.revenuecat.com/v1/receipts")!,
            statusCode: HTTPStatusCode.tooManyRequests.rawValue,
            httpVersion: nil,
            headerFields: [
                HTTPClient.ResponseHeader.retryAfter.rawValue: "\(retryAfterSecondsDecimal)"
            ]
        )!

        backoffPeriod = self.client.calculateRetryBackoffTime(forResponse: httpURLResponse, retryCount: 2)
        expect(backoffPeriod).to(equal(TimeInterval(retryAfterSecondsDecimal)))
    }

    func testUses0msBackoffIfServerProvidedBackoffIsNegative() {
        let httpURLResponse = HTTPURLResponse(
            url: URL(string: "https://api.revenuecat.com/v1/receipts")!,
            statusCode: HTTPStatusCode.tooManyRequests.rawValue,
            httpVersion: nil,
            headerFields: [
                HTTPClient.ResponseHeader.retryAfter.rawValue: "-1"
            ]
        )!

        let backoffPeriod = self.client.calculateRetryBackoffTime(forResponse: httpURLResponse, retryCount: 2)
        expect(backoffPeriod).to(equal(TimeInterval(0)))
    }

    func testUses1hourBackoffIfServerProvidedBackoffIsGreaterThan1hour() {
        let oneHourInSeconds = 3_600
        let httpURLResponse = HTTPURLResponse(
            url: URL(string: "https://api.revenuecat.com/v1/receipts")!,
            statusCode: HTTPStatusCode.tooManyRequests.rawValue,
            httpVersion: nil,
            headerFields: [
                HTTPClient.ResponseHeader.retryAfter.rawValue: "\(oneHourInSeconds * 2)"
            ]
        )!

        let backoffPeriod = self.client.calculateRetryBackoffTime(forResponse: httpURLResponse, retryCount: 2)
        expect(backoffPeriod).to(equal(TimeInterval(Double(oneHourInSeconds))))
    }

    func testUsesDefaultBackoffIfServerProvidedBackoffIsEmptyString() {
        let httpURLResponse = HTTPURLResponse(
            url: URL(string: "https://api.revenuecat.com/v1/receipts")!,
            statusCode: HTTPStatusCode.tooManyRequests.rawValue,
            httpVersion: nil,
            headerFields: [
                HTTPClient.ResponseHeader.retryAfter.rawValue: ""
            ]
        )!

        let backoffPeriod = self.client.calculateRetryBackoffTime(forResponse: httpURLResponse, retryCount: 2)
        expect(backoffPeriod).to(equal(TimeInterval(0.75)))
    }

    func testUsesDefaultBackoffIfServerProvidedBackoffMissing() {
        let httpURLResponse = HTTPURLResponse(
            url: URL(string: "https://api.revenuecat.com/v1/receipts")!,
            statusCode: HTTPStatusCode.tooManyRequests.rawValue,
            httpVersion: nil,
            headerFields: [:]
        )!

        let backoffPeriod = self.client.calculateRetryBackoffTime(forResponse: httpURLResponse, retryCount: 2)
        expect(backoffPeriod).to(equal(TimeInterval(0.75)))
    }

    func testPerformsAllRetriesIfAlwaysGetsRetryableStatusCode() throws {
        var requestCount = 0

        let host = try XCTUnwrap(HTTPRequest.Path.serverHostURL.host)
        stub(condition: isHost(host)) { _ in
            requestCount += 1
            return .emptyTooManyRequestsResponse()
        }

        let request = HTTPRequest(method: .get, path: .receiptPath, isRetryable: true)
        let result = waitUntilValue { completion in
            self.client.perform(request) { (response: EmptyResponse) in
                completion(response)
            }
        }
        expect(requestCount).to(equal(4)) // 1 original request + 3 retries

        expect(result).toNot(beNil())
        expect(result).to(beFailure())

        let error = try XCTUnwrap(result?.error)
        expect(error) == .errorResponse(
            .init(code: .unknownError,
                  originalCode: 0,
                  message: nil),
            .tooManyRequests
        )
        expect(error.isServerDown) == false
    }

    func testCorrectDelaysAreSentToOperationDispatcherForRetries() throws {

        let host = try XCTUnwrap(HTTPRequest.Path.serverHostURL.host)
        stub(condition: isHost(host)) { _ in
            return .emptyTooManyRequestsResponse()
        }

        let mockOperationDispatcher = MockOperationDispatcher()
        let client = self.createClient(self.systemInfo, operationDispatcher: mockOperationDispatcher)

        let request = HTTPRequest(method: .get, path: .receiptPath, isRetryable: true)
        _ = waitUntilValue { completion in
            client.perform(request) { (response: EmptyResponse) in
                completion(response)
            }
        }

        expect(mockOperationDispatcher.invokedDispatchOnWorkerThreadWithTimeIntervalCount).to(equal(3))
        expect(mockOperationDispatcher.invokedDispatchOnWorkerThreadWithTimeIntervalParams).to(equal([
            TimeInterval(0),
            TimeInterval(0.75),
            TimeInterval(3)
        ]))
    }

    func testRetryMessagesAreLoggedWhenRetriesExhausted() throws {
        var requestCount = 0

        let host = try XCTUnwrap(HTTPRequest.Path.serverHostURL.host)
        stub(condition: isHost(host)) { _ in
            requestCount += 1
            return .emptyTooManyRequestsResponse()
        }

        let request = HTTPRequest(method: .get, path: .receiptPath, isRetryable: true)
        _ = waitUntilValue { completion in
            self.client.perform(request) { (response: EmptyResponse) in
                completion(response)
            }
        }
        self.logger.verifyMessageWasLogged(
            "Queued request GET /v1/receipts for retry number 1 in 0.0 seconds."
        )
        self.logger.verifyMessageWasLogged(
            "Queued request GET /v1/receipts for retry number 2 in 0.75 seconds."
        )
        self.logger.verifyMessageWasLogged(
            "Queued request GET /v1/receipts for retry number 3 in 3.0 seconds."
        )
        self.logger.verifyMessageWasLogged("Request GET /v1/receipts failed all 3 retries.")
    }

    func testRetryMessagesAreNotLoggedWhenNoRetriesOccur() throws {
        let host = try XCTUnwrap(HTTPRequest.Path.serverHostURL.host)
        stub(condition: isHost(host)) { _ in
            return .emptySuccessResponse()
        }

        let request = HTTPRequest(method: .get, path: .mockPath)
        _ = waitUntilValue { completion in
            self.client.perform(request) { (response: EmptyResponse) in
                completion(response)
            }
        }
        self.logger.verifyMessageWasNotLogged(
            "Queued request GET /v1/subscribers/identify for retry number 1 in 0.0 seconds."
        )
        self.logger.verifyMessageWasNotLogged(
            "Queued request GET /v1/subscribers/identify for retry number 2 in 0.75 seconds."
        )
        self.logger.verifyMessageWasNotLogged(
            "Queued request GET /v1/subscribers/identify for retry number 3 in 3.0 seconds."
        )
        self.logger.verifyMessageWasNotLogged("Request GET /v1/subscribers/identify failed all 3 retries.")
    }

    func testRetryCountHeaderIsAccurateWithNoRetries() throws {
        var retryCountHeaderValues: [String?] = []

        let host = try XCTUnwrap(HTTPRequest.Path.serverHostURL.host)
        stub(condition: isHost(host)) { urlRequest in
            let retryCountHeaderValue = urlRequest.allHTTPHeaderFields?[HTTPClient.RequestHeader.retryCount.rawValue]
            retryCountHeaderValues.append(retryCountHeaderValue)

            return .emptySuccessResponse()
        }

        let request = HTTPRequest(method: .get, path: .mockPath)
        _ = waitUntilValue { completion in
            self.client.perform(request) { (response: EmptyResponse) in
                completion(response)
            }
        }
        expect(retryCountHeaderValues).to(equal(["0"]))
    }

    func testDoesNotRetryUnsupportedURLPaths() throws {
        let host = try XCTUnwrap(HTTPRequest.Path.serverHostURL.host)
        var requestCount = 0
        stub(condition: isHost(host)) { _ in
            requestCount += 1
            return .emptyTooManyRequestsResponse()
        }

        let request = HTTPRequest(method: .get, path: .mockPath) // This is the logIn path
        _ = waitUntilValue { completion in
            self.client.perform(request) { (response: EmptyResponse) in
                completion(response)
            }
        }
        expect(requestCount).to(equal(1))
    }

    func testRetryCountHeaderIsAccurateWithOnlyOneRetry() throws {
        var retryCountHeaderValues: [String?] = []
        var retryCount = 0

        let host = try XCTUnwrap(HTTPRequest.Path.serverHostURL.host)
        stub(condition: isHost(host)) { urlRequest in
            let retryCountHeaderValue = urlRequest.allHTTPHeaderFields?[HTTPClient.RequestHeader.retryCount.rawValue]
            retryCountHeaderValues.append(retryCountHeaderValue)

            if retryCount == 0 {
                retryCount += 1
                return .emptyTooManyRequestsResponse()
            } else {
                retryCount += 1
                return .emptySuccessResponse()
            }
        }

        let request = HTTPRequest(method: .get, path: .receiptPath, isRetryable: true)
        _ = waitUntilValue { completion in
            self.client.perform(request) { (response: EmptyResponse) in
                completion(response)
            }
        }
        expect(retryCountHeaderValues).to(equal(["0", "1"]))
    }

    func testRetryCountHeaderIsAccurateWhenAllRetriesAreExhausted() throws {
        var retryCountHeaderValues: [String?] = []

        let host = try XCTUnwrap(HTTPRequest.Path.serverHostURL.host)
        stub(condition: isHost(host)) { urlRequest in
            let retryCountHeaderValue = urlRequest.allHTTPHeaderFields?[HTTPClient.RequestHeader.retryCount.rawValue]
            retryCountHeaderValues.append(retryCountHeaderValue)

            return .emptyTooManyRequestsResponse()
        }

        let request = HTTPRequest(method: .get, path: .receiptPath, isRetryable: true)
        _ = waitUntilValue { completion in
            self.client.perform(request) { (response: EmptyResponse) in
                completion(response)
            }
        }
        expect(retryCountHeaderValues).to(equal(["0", "1", "2", "3"]))
    }

    func testSucceedsIfAlwaysGetsSuccessAfterOneRetry() throws {
        var requestCount = 0

        let host = try XCTUnwrap(HTTPRequest.Path.serverHostURL.host)
        stub(condition: isHost(host)) { _ in
            requestCount += 1

            if requestCount >= 2 {
                return .emptySuccessResponse()
            } else {
                return .emptyTooManyRequestsResponse()
            }
        }

        let request = HTTPRequest(method: .get, path: .receiptPath, isRetryable: true)
        let result = waitUntilValue { completion in
            self.client.perform(request) { (response: EmptyResponse) in
                completion(response)
            }
        }
        expect(requestCount).to(equal(2)) // 1 original request + 1 retries

        expect(result).toNot(beNil())
        expect(result).to(beSuccess())

        self.logger.verifyMessageWasLogged(
            "Queued request GET /v1/receipts for retry number 1 in 0.0 seconds."
        )
        self.logger.verifyMessageWasNotLogged(
            "Queued request GET /v1/receipts for retry number 2 in 0.75 seconds."
        )
        self.logger.verifyMessageWasNotLogged(
            "Queued request GET /v1/receipts for retry number 3 in 3.0 seconds."
        )
        self.logger.verifyMessageWasNotLogged(
            "Request GET /v1/receipts failed all 3 retries."
        )

        expect(self.signing.requests).to(beEmpty())
    }

    func testRetryRequestIfNeededDoesntRetryRequestWithNilHTTPURLResponse() {
        let mockOperationDispatcher = MockOperationDispatcher()
        let client = self.createClient(self.systemInfo, operationDispatcher: mockOperationDispatcher)

        let didRetry = client.retryRequestIfNeeded(
            request: buildEmptyRequest(isRetryable: true),
            httpURLResponse: nil
        )

        expect(didRetry).to(beFalse())
    }

    func testRetryRequestIfNeededDoesntRetryRequestWithNonRetryableHTTPStatusCode() {
        let mockOperationDispatcher = MockOperationDispatcher()
        let client = self.createClient(self.systemInfo, operationDispatcher: mockOperationDispatcher)

        let didRetry = client.retryRequestIfNeeded(
            request: buildEmptyRequest(isRetryable: true),
            httpURLResponse: HTTPURLResponse(
                url: URL(string: "https://api.revenuecat.com/v1/receipts")!,
                statusCode: HTTPStatusCode.success.rawValue,
                httpVersion: nil,
                headerFields: nil
            )
        )

        expect(didRetry).to(beFalse())
    }

    func testRetryRequestIfNeededDoesntRetryRequestWithTooManyExistingRetries() {
        let mockOperationDispatcher = MockOperationDispatcher()
        let client = self.createClient(self.systemInfo, operationDispatcher: mockOperationDispatcher)

        let requestThatHasBeenRetriedManyTimes = buildEmptyRequest(isRetryable: true)
            .retriedRequest()
            .retriedRequest()
            .retriedRequest()
            .retriedRequest()
            .retriedRequest()
            .retriedRequest()

        let didRetry = client.retryRequestIfNeeded(
            request: requestThatHasBeenRetriedManyTimes,
            httpURLResponse: HTTPURLResponse(
                url: URL(string: "https://api.revenuecat.com/v1/receipts")!,
                statusCode: HTTPStatusCode.tooManyRequests.rawValue,
                httpVersion: nil,
                headerFields: nil
            )
        )

        expect(didRetry).to(beFalse())
    }

    func testRetryRequestIfNeededRetriesEligibleRequest() {
        let mockOperationDispatcher = MockOperationDispatcher()
        let client = self.createClient(self.systemInfo, operationDispatcher: mockOperationDispatcher)

        let requestThatHasBeenRetriedManyTimes = buildEmptyRequest(isRetryable: true)

        let didRetry = client.retryRequestIfNeeded(
            request: requestThatHasBeenRetriedManyTimes,
            httpURLResponse: HTTPURLResponse(
                url: URL(string: "https://api.revenuecat.com/v1/receipts")!,
                statusCode: HTTPStatusCode.tooManyRequests.rawValue,
                httpVersion: nil,
                headerFields: nil
            )
        )

        expect(didRetry).to(beTrue())
        expect(mockOperationDispatcher.invokedDispatchOnWorkerThreadWithTimeInterval).to(beTrue())
        expect(mockOperationDispatcher.invokedDispatchOnWorkerThreadWithTimeIntervalCount).to(equal(1))
        expect(mockOperationDispatcher.invokedDispatchOnWorkerThreadWithTimeIntervalParam).to(equal(0))
    }
}

// swiftlint:disable large_tuple

private func matchTrackParams(
    _ data: (String, TimeInterval, Bool, Int, Int?, HTTPResponseOrigin?, VerificationResult)
) -> Nimble.Predicate<(String, TimeInterval, Bool, Int, Int?, HTTPResponseOrigin?, VerificationResult)> {
    return .init {
        let other = try $0.evaluate()
        let timeInterval = other?.1 ?? -1
        let matches = (other?.0 == data.0 &&
                       timeInterval > 0 && timeInterval.isLess(than: 1) &&
                       other?.2 == data.2 &&
                       other?.3 == data.3 &&
                       other?.4 == data.4 &&
                       other?.5 == data.5 &&
                       other?.6 == data.6)

        return .init(bool: matches, message: .fail("Diagnostics tracked params do not match"))
    }
}

// swiftlint:enable large_tuple

func isPath(_ path: HTTPRequestPath) -> HTTPStubsTestBlock {
    return isPath(path.relativePath)
}

extension HTTPStubsResponse {

    static func emptySuccessResponse() -> HTTPStubsResponse {
        // `HTTPStubsResponse` doesn't have value semantics, it's a mutable class!
        // This creates a new response each time so modifications in one test don't affect others.
        return .init(data: Data(),
                     statusCode: .success,
                     headers: nil)
    }

    static func emptyTooManyRequestsResponse() -> HTTPStubsResponse {
        // `HTTPStubsResponse` doesn't have value semantics, it's a mutable class!
        // This creates a new response each time so modifications in one test don't affect others.
        return .init(data: Data(),
                     statusCode: .tooManyRequests,
                     headers: nil)
    }

    convenience init(data: Data, statusCode: HTTPStatusCode, headers: HTTPClient.RequestHeaders?) {
        self.init(data: data, statusCode: Int32(statusCode.rawValue), headers: headers)
    }

}

// MARK: - Extensions

private extension BaseHTTPClientTests {

    static func extractRequestNumber(from urlRequest: URLRequest) -> Int? {
        do {
            let requestData = try XCTUnwrap(urlRequest.ohhttpStubs_httpBody)
            let body = try JSONDecoder.default.decode(
                AnyEncodableRequestBody.self,
                from: requestData
            ).body

            let dictionary = try XCTUnwrap(body.value as? [String: Any])
            let number = dictionary[Self.requestNumberKeyName]

            return try XCTUnwrap(number as? Int)
        } catch {
            XCTFail("Couldn't extract the request number from the URLRequest")
            return nil
        }
    }

    static var requestNumberKeyName: String { "request_number" }

}

extension BaseHTTPClientTests {

    struct BodyWithDate: Equatable, Codable, HTTPResponseBody {
        var data: String
        var requestDate: Date

        func copy(with newRequestDate: Date) -> Self {
            var copy = self
            copy.requestDate = newRequestDate
            return copy
        }
    }

    struct BodyWithSignature: HTTPRequestBody, Equatable {
        var key1: String
        var key2: String

        var contentForSignature: [(key: String, value: String?)] {
            return [
                ("key1", self.key1),
                ("key2", self.key2)
            ]
        }
    }

}

extension HTTPRequest.Path {

    // Doesn't matter which path this is, we stub requests to it.
    static let mockPath: Self = .logIn
    static let receiptPath: Self = .postReceiptData

}

extension HTTPRequest.Method {

    fileprivate static func requestNumber(_ number: Int) -> Self {
        return .post([HTTPClientTests.requestNumberKeyName: number])
    }

    fileprivate static func invalidBody() -> Self {
        // infinity can't be cast into JSON, so we use it to force a parsing exception. See:
        // https://developer.apple.com/documentation/foundation/nsjsonserialization?language=objc
        let nonJSONBody = ["something": Double.infinity]

        return .post(nonJSONBody)
    }

    /// Creates a `HTTPRequest.Method.post` request with `[String: Any]`.
    /// - Note: this is for testing only, real requests must use `Encodable`.
    internal static func post(_ body: [String: Any]) -> Self {
        return .post(AnyEncodableRequestBody(body))
    }

}

private struct AnyEncodableRequestBody: HTTPRequestBody, Decodable {

    var body: AnyEncodable

    init(_ body: [String: Any]) {
        self.body = .init(body)
    }

    var contentForSignature: [(key: String, value: String?)] { [] }

}