firebase-ios-sdk/Firestore/Example/Tests/GoogleTest/FSTGoogleTestTests.mm

/*
 * Copyright 2017 Google
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

#import <XCTest/XCTest.h>
#import <objc/runtime.h>

#import "Firestore/Source/Util/FSTAssert.h"

#include "gtest/gtest.h"

/**
 * An XCTest test case that finds C++ test cases written in the GoogleTest framework, runs them, and
 * reports the results back to Xcode. This allows tests written in C++ that don't rely on XCTest to
 * coexist in this project.
 *
 * As an extra feature, you can run all C++ tests by focusing on the GoogleTests class.
 *
 * Each GoogleTest TestCase is mapped to a dynamically generated XCTestCase class. Each GoogleTest
 * TEST() is mapped to a test method on that XCTestCase.
 */
@interface GoogleTests : XCTestCase
@end

namespace {

// A testing::TestCase named "Foo" corresponds to an XCTestCase named "FooTests".
NSString *const kTestCaseSuffix = @"Tests";

// A testing::TestInfo named "Foo" corresponds to test method named "testFoo".
NSString *const kTestMethodPrefix = @"test";

// A map of keys created by TestInfoKey to the corresponding testing::TestInfo (wrapped in an
// NSValue). The generated XCTestCase classes are discovered and instantiated by XCTest so this is
// the only means of plumbing per-test-method state into these methods.
NSDictionary<NSString *, NSValue *> *testInfosByKey;

// If the user focuses on GoogleTests itself, this means force all C++ tests to run.
BOOL forceAllTests = NO;

/**
 * Loads this XCTest runner's configuration file and figures out which tests to run based on the
 * contents of that configuration file.
 *
 * @return the set of tests to run, or nil if the user asked for all tests or if there's any
 *     problem loading or parsing the configuration.
 */
NSSet<NSString *> *_Nullable LoadXCTestConfigurationTestsToRun() {
  // Xcode invokes the test runner with an XCTestConfigurationFilePath environment variable set to
  // the path of a configuration file containing, among other things, the set of tests to run. The
  // configuration file deserializes to a non-public XCTestConfiguration class.
  //
  // This loads that file and then reflectively pulls out the testsToRun set. Just in case any of
  // these private details should change in the future and something should fail here, the mechanism
  // complains but fails open. This way the worst that can happen is that users end up running more
  // tests than they intend, but we never accidentally show a green run that wasn't.
  static NSString *const configEnvVar = @"XCTestConfigurationFilePath";

  NSDictionary<NSString *, NSString *> *env = [[NSProcessInfo processInfo] environment];
  NSString *filePath = [env objectForKey:configEnvVar];
  if (!filePath) {
    NSLog(@"Missing %@ environment variable; assuming all tests", configEnvVar);
    return nil;
  }

  id config = [NSKeyedUnarchiver unarchiveObjectWithFile:filePath];
  if (!config) {
    NSLog(@"Failed to load any configuaration from %@=%@", configEnvVar, filePath);
    return nil;
  }

  SEL testsToRunSelector = NSSelectorFromString(@"testsToRun");
  if (![config respondsToSelector:testsToRunSelector]) {
    NSLog(@"Invalid configuaration from %@=%@: missing testsToRun", configEnvVar, filePath);
    return nil;
  }

  // Invoke the testsToRun selector safely. This indirection is required because just calling
  // -performSelector: fails to properly retain the NSSet under ARC.
  typedef NSSet<NSString *> *(*TestsToRunFunction)(id, SEL);
  IMP testsToRunMethod = [config methodForSelector:testsToRunSelector];
  auto testsToRunFunction = reinterpret_cast<TestsToRunFunction>(testsToRunMethod);
  return testsToRunFunction(config, testsToRunSelector);
}

/**
 * Creates a GoogleTest filter specification, suitable for passing to the --gtest_filter flag,
 * that limits GoogleTest to running the same set of tests that Xcode requested.
 *
 * Each member of the testsToRun set is mapped as follows:
 *
 *   * Bare class: "ClassTests" => "Class.*"
 *   * Class and method: "ClassTests/testMethod" => "Class.Method"
 *
 * These members are then joined with a ":" as googletest requires.
 *
 * @see https://github.com/google/googletest/blob/master/googletest/docs/AdvancedGuide.md
 */
NSString *CreateTestFiltersFromTestsToRun(NSSet<NSString *> *testsToRun) {
  NSMutableString *result = [[NSMutableString alloc] init];
  for (NSString *spec in testsToRun) {
    NSArray<NSString *> *parts = [spec componentsSeparatedByString:@"/"];

    NSString *gtestCaseName = nil;
    if (parts.count > 0) {
      NSString *className = parts[0];
      if ([className hasSuffix:kTestCaseSuffix]) {
        gtestCaseName = [className substringToIndex:className.length - kTestCaseSuffix.length];
      }
    }

    NSString *gtestMethodName = nil;
    if (parts.count > 1) {
      NSString *methodName = parts[1];
      if ([methodName hasPrefix:kTestMethodPrefix]) {
        gtestMethodName = [methodName substringFromIndex:kTestMethodPrefix.length];
      }
    }

    if (gtestCaseName) {
      if (result.length > 0) {
        [result appendString:@":"];
      }
      [result appendString:gtestCaseName];
      [result appendString:@"."];
      [result appendString:(gtestMethodName ? gtestMethodName : @"*")];
    }
  }

  return result;
}

/** Returns the name of the selector for the test method representing this specific test. */
NSString *SelectorNameForTestInfo(const testing::TestInfo *testInfo) {
  return [NSString stringWithFormat:@"%@%s", kTestMethodPrefix, testInfo->name()];
}

/** Returns the name of the class representing the given testing::TestCase. */
NSString *ClassNameForTestCase(const testing::TestCase *testCase) {
  return [NSString stringWithFormat:@"%s%@", testCase->name(), kTestCaseSuffix];
}

/**
 * Returns a key name for the testInfosByKey dictionary. Each (class, selector) pair corresponds
 * to a unique GoogleTest result.
 */
NSString *TestInfoKey(Class testClass, SEL testSelector) {
  return [NSString
      stringWithFormat:@"%@.%@", NSStringFromClass(testClass), NSStringFromSelector(testSelector)];
}

/**
 * Looks up the testing::TestInfo for this test method and reports on the outcome to XCTest, as if
 * the test actually ran in this method.
 *
 * Note: this function is the implementation for each generated test method. It shouldn't be used
 * directly. The parameter names of self and _cmd match up with the implicit parameters passed to
 * any Objective-C method. Naming them this way here allows XCTAssert and friends to work.
 */
void ReportTestResult(XCTestCase *self, SEL _cmd) {
  NSString *testInfoKey = TestInfoKey([self class], _cmd);
  NSValue *holder = testInfosByKey[testInfoKey];
  auto testInfo = static_cast<const testing::TestInfo *>(holder.pointerValue);
  if (!testInfo) {
    return;
  }

  if (!testInfo->should_run()) {
    // Test was filtered out by gunit; nothing to report.
    return;
  }

  const testing::TestResult *result = testInfo->result();
  if (result->Passed()) {
    // Let XCode know that the test ran and succeeded.
    XCTAssertTrue(true);
    return;
  }

  // Test failed :-(. Record the failure such that XCode will navigate directly to the file:line.
  int parts = result->total_part_count();
  for (int i = 0; i < parts; i++) {
    const testing::TestPartResult &part = result->GetTestPartResult(i);
    [self recordFailureWithDescription:@(part.message())
                                inFile:@(part.file_name() ? part.file_name() : "")
                                atLine:(part.line_number() > 0 ? part.line_number() : 0)
                              expected:YES];
  }
}

/**
 * Generates a new subclass of XCTestCase for the given GoogleTest TestCase. Each TestInfo (which
 * represents an indivudal test method execution) is translated into a method on the test case.
 *
 * @param The testing::TestCase of interest to translate.
 * @param A map of TestInfoKeys to testing::TestInfos, populated by this method.
 *
 * @return A new Class that's a subclass of XCTestCase, that's been registered with the Objective-C
 *     runtime.
 */
Class CreateXCTestCaseClass(const testing::TestCase *testCase,
                            NSMutableDictionary<NSString *, NSValue *> *infoMap) {
  NSString *testCaseName = ClassNameForTestCase(testCase);
  Class testClass = objc_allocateClassPair([XCTestCase class], [testCaseName UTF8String], 0);

  // Create a method for each TestInfo.
  int testInfos = testCase->total_test_count();
  for (int j = 0; j < testInfos; j++) {
    const testing::TestInfo *testInfo = testCase->GetTestInfo(j);

    NSString *selectorName = SelectorNameForTestInfo(testInfo);
    SEL selector = sel_registerName([selectorName UTF8String]);

    // Use the ReportTestResult function as the method implementation. The v@: indicates it is a
    // void objective-C method; this must continue to match the signature of ReportTestResult.
    IMP method = reinterpret_cast<IMP>(ReportTestResult);
    class_addMethod(testClass, selector, method, "v@:");

    NSString *infoKey = TestInfoKey(testClass, selector);
    NSValue *holder = [NSValue valueWithPointer:testInfo];
    infoMap[infoKey] = holder;
  }
  objc_registerClassPair(testClass);

  return testClass;
}

/**
 * Creates a test suite containing all C++ tests, used when the user starts the GoogleTests class.
 *
 * Note: normally XCTest finds all the XCTestCase classes that are registered with the run time
 * and asks them to create suites for themselves. When a user focuses on the GoogleTests class,
 * XCTest no longer does this so we have to force XCTest to see more tests than it would normally
 * look at so that the indicators in the test navigator update properly.
 */
XCTestSuite *CreateAllTestsTestSuite() {
  XCTestSuite *allTestsSuite = [[XCTestSuite alloc] initWithName:@"All GoogleTest Tests"];
  [allTestsSuite addTest:[XCTestSuite testSuiteForTestCaseClass:[GoogleTests class]]];

  const testing::UnitTest *master = testing::UnitTest::GetInstance();

  int testCases = master->total_test_case_count();
  for (int i = 0; i < testCases; i++) {
    const testing::TestCase *testCase = master->GetTestCase(i);
    NSString *testCaseName = ClassNameForTestCase(testCase);
    Class testClass = objc_getClass([testCaseName UTF8String]);
    [allTestsSuite addTest:[XCTestSuite testSuiteForTestCaseClass:testClass]];
  }

  return allTestsSuite;
}

/**
 * Finds and runs googletest-based tests based on the XCTestConfiguration of the current test
 * invocation.
 */
void RunGoogleTestTests() {
  NSString *masterTestCaseName = NSStringFromClass([GoogleTests class]);

  // Initialize GoogleTest but don't run the tests yet.
  int argc = 1;
  const char *argv[] = {[masterTestCaseName UTF8String]};
  testing::InitGoogleTest(&argc, const_cast<char **>(argv));

  // Convert XCTest's testToRun set to the equivalent --gtest_filter flag.
  //
  // Note that we only set forceAllTests to YES if the user specifically focused on GoogleTests.
  // This prevents XCTest double-counting test cases (and failures) when a user asks for all tests.
  NSSet<NSString *> *allTests = [NSSet setWithObject:masterTestCaseName];
  NSSet<NSString *> *testsToRun = LoadXCTestConfigurationTestsToRun();
  if (testsToRun) {
    if ([allTests isEqual:testsToRun]) {
      NSLog(@"Forcing all tests to run");
      forceAllTests = YES;
    } else {
      NSString *filters = CreateTestFiltersFromTestsToRun(testsToRun);
      NSLog(@"Using --gtest_filter=%@", filters);
      if (filters) {
        testing::GTEST_FLAG(filter) = [filters UTF8String];
      }
    }
  }

  // Create XCTestCases and populate the testInfosByKey map
  const testing::UnitTest *master = testing::UnitTest::GetInstance();
  NSMutableDictionary<NSString *, NSValue *> *infoMap =
      [NSMutableDictionary dictionaryWithCapacity:master->total_test_count()];

  int testCases = master->total_test_case_count();
  for (int i = 0; i < testCases; i++) {
    const testing::TestCase *testCase = master->GetTestCase(i);
    CreateXCTestCaseClass(testCase, infoMap);
  }
  testInfosByKey = infoMap;

#pragma clang diagnostic push
#pragma clang diagnostic ignored "-Wunused-result"
  // RUN_ALL_TESTS by default doesn't want you to ignore its result, but it's safe here. Test
  // failures are already logged by GoogleTest itself (and then again by XCTest). Test failures are
  // reported via -recordFailureWithDescription:inFile:atLine:expected: which then causes XCTest
  // itself to fail the run.
  RUN_ALL_TESTS();
#pragma clang diagnostic pop
}

}  // namespace

@implementation GoogleTests

+ (XCTestSuite *)defaultTestSuite {
  // Only return all tests beyond GoogleTests if the user is focusing on GoogleTests.
  if (forceAllTests) {
    return CreateAllTestsTestSuite();
  } else {
    // just run the tests that are a part of this class
    return [XCTestSuite testSuiteForTestCaseClass:[self class]];
  }
}

- (void)testGoogleTestsActuallyRun {
  // This whole mechanism is sufficiently tricky that we should verify that the build actually
  // plumbed this together correctly.
  const testing::UnitTest *master = testing::UnitTest::GetInstance();
  XCTAssertGreaterThan(master->total_test_case_count(), 0);
}

@end

/**
 * This class is registered as the NSPrincipalClass in the Firestore_Tests bundle's Info.plist.
 * XCTest instantiates this class to perform one-time setup for the test bundle, as documented
 * here:
 *
 *   https://developer.apple.com/documentation/xctest/xctestobservationcenter
 */
@interface FSTGoogleTestsPrincipal : NSObject
@end

@implementation FSTGoogleTestsPrincipal

- (instancetype)init {
  self = [super init];
  RunGoogleTestTests();
  return self;
}

@end