Reland "[ios] Adds the ability to run unittests using XCTest."

Original change's description:
> Revert "[ios] Adds the ability to run unittests using XCTest."
> 
> This reverts commit b6c231b5.
> 
> Reason for revert: Suspected for causing compiling errors on mac.
> 
> Original change's description:
> > [ios] Adds the ability to run unittests using XCTest.
> > 
> > This new functionality is hidden behind both a GN arg
> > (enable_run_ios_unittests_with_xctest) and a commandline switch
> > (--enable-run-unittests-with-xctest), in order to default it to off
> > until the bots are updated to properly run XCTest-based unittests.
> > 
> > The iOS test runner is updated to run in one of two modes.  When
> > --enable-run-unittests-with-xctest is false (the default), behavior is
> > unchanged; TestSuite::Run() calls UIApplicationMain(), then the
> > UIApplicationDelegate calls TestSuite::Run() again, which actually runs
> > the tests when invoked the second time.  When the switch is set to true,
> > the second invocation of TestSuite::Run() is made by our XCTestCase
> > subclass rather than by the application delegate.
> > 
> > Xcode provides the ability to run XCTests and XCUITests from the
> > commandline, but does not provide any other way to install and run an
> > app outside of this test-based workflow.  (We had an alternative that
> > used third party libraries, but they no longer work on iOS 13.)  This
> > makes it difficult to install and run GoogleTest-based tests on iOS
> > devices, since they run as a single self-contained application, but it
> > would not be practical to drop GoogleTest support on iOS.  Instead, we
> > are exploring invoking these tests via XCTest, which would allow us to
> > use Xcode's tooling but still run the same GoogleTest-based tests as on
> > other platforms.
> > 
> > BUG=635509
> > 
> > Change-Id: I26c67d9c7e16a744f43a20f2d8c5839ca8b3c31a
> > Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1787593
> > Reviewed-by: Dirk Pranke <dpranke@chromium.org>
> > Reviewed-by: Mark Mentovai <mark@chromium.org>
> > Reviewed-by: Justin Cohen <justincohen@chromium.org>
> > Commit-Queue: Rohit Rao <rohitrao@chromium.org>
> > Cr-Commit-Position: refs/heads/master@{#694749}
> 
> TBR=rohitrao@chromium.org,dpranke@chromium.org,justincohen@chromium.org,mark@chromium.org
> 
> Change-Id: Ic67605ab0292551500a163e993c6d93fec3048c0
> No-Presubmit: true
> No-Tree-Checks: true
> No-Try: true
> Bug: 635509,1002144
> Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1791798
> Reviewed-by: Tarun Bansal <tbansal@chromium.org>
> Commit-Queue: Tarun Bansal <tbansal@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#694814}

TBR=rohitrao@chromium.org,dpranke@chromium.org,justincohen@chromium.org,tbansal@chromium.org,mark@chromium.org

Change-Id: I94e59823c379e1afb4e9e965bfe602d06400e8b5
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Bug: 635509, 1002144
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1790069Reviewed-by: Rohit Rao <rohitrao@chromium.org>
Reviewed-by: Mark Mentovai <mark@chromium.org>
Commit-Queue: Rohit Rao <rohitrao@chromium.org>
Cr-Commit-Position: refs/heads/master@{#694950}

base/test/BUILD.gn

@@ -228,6 +228,7 @@ static_library("test_support") {
     set_sources_assignment_filter([])
     sources += [ "test_file_util_mac.cc" ]
     set_sources_assignment_filter(sources_assignment_filter)
+    deps += [ ":google_test_runner_shared_headers" ]
   }
 
   if (is_mac) {
@@ -513,6 +514,29 @@ if (is_android) {
   }
 }
 
+if (is_ios) {
+  source_set("google_test_runner_shared_headers") {
+    sources = [
+      "ios/google_test_runner_delegate.h",
+    ]
+  }
+
+  source_set("google_test_runner") {
+    sources = [
+      "ios/google_test_runner.mm",
+    ]
+    deps = [
+      ":google_test_runner_shared_headers",
+      "//base",
+    ]
+    libs = [ "UIKit.framework" ]
+    configs += [
+      "//build/config/compiler:enable_arc",
+      "//build/config/ios:xctest_config",
+    ]
+  }
+}
+
 # Trivial executable which outputs space-delimited argv to stdout,
 # used for testing.
 executable("test_child_process") {

base/test/ios/google_test_runner.mm

+// Copyright 2019 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#import <UIKit/UIKit.h>
+#import <XCTest/XCTest.h>
+
+#include "base/logging.h"
+#import "base/test/ios/google_test_runner_delegate.h"
+
+#if !defined(__has_feature) || !__has_feature(objc_arc)
+#error "This file requires ARC support."
+#endif
+
+@interface GoogleTestRunner : XCTestCase
+@end
+
+@implementation GoogleTestRunner
+
+- (void)testRunGoogleTests {
+  id appDelegate = UIApplication.sharedApplication.delegate;
+  DCHECK([appDelegate conformsToProtocol:@protocol(GoogleTestRunnerDelegate)]);
+
+  id<GoogleTestRunnerDelegate> runnerDelegate =
+      static_cast<id<GoogleTestRunnerDelegate>>(appDelegate);
+  DCHECK(runnerDelegate.supportsRunningGoogleTests);
+  XCTAssertTrue([runnerDelegate runGoogleTests] == 0);
+}
+
+@end

base/test/ios/google_test_runner_delegate.h

+// Copyright 2019 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#ifndef BASE_TEST_IOS_GOOGLE_TEST_RUNNER_DELEGATE_H_
+#define BASE_TEST_IOS_GOOGLE_TEST_RUNNER_DELEGATE_H_
+
+@protocol GoogleTestRunnerDelegate
+
+// Returns YES if this delegate supports running GoogleTests via a call to
+// |runGoogleTests|.
+@property(nonatomic, readonly, assign) BOOL supportsRunningGoogleTests;
+
+// Runs GoogleTests and returns the final exit code.
+- (int)runGoogleTests;
+
+@end
+
+#endif  // BASE_TEST_IOS_GOOGLE_TEST_RUNNER_DELEGATE_H_

base/test/test_support_ios.h

@@ -19,6 +19,9 @@ void InitIOSRunHook(TestSuite* suite, int argc, char* argv[]);
 // InitIOSRunHook.
 void RunTestsFromIOSApp();
 
+// Returns true if unittests should be run by the XCTest runnner.
+bool ShouldRunIOSUnittestsWithXCTest();
+
 }  // namespace base
 
 #endif  // BASE_TEST_TEST_SUPPORT_IOS_H_

base/test/test_support_ios.mm

@@ -2,14 +2,19 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
+#import "base/test/test_support_ios.h"
+
 #import <UIKit/UIKit.h>
 
+#include "base/command_line.h"
 #include "base/debug/debugger.h"
 #include "base/logging.h"
 #include "base/mac/scoped_nsobject.h"
 #include "base/message_loop/message_pump.h"
 #include "base/message_loop/message_pump_default.h"
+#import "base/test/ios/google_test_runner_delegate.h"
 #include "base/test/test_suite.h"
+#include "base/test/test_switches.h"
 #include "testing/coverage_util_ios.h"
 
 // Springboard will kill any iOS app that fails to check in after launch within
@@ -45,7 +50,7 @@ static char** g_argv;
 @end
 #endif  // TARGET_IPHONE_SIMULATOR
 
-@interface ChromeUnitTestDelegate : NSObject {
+@interface ChromeUnitTestDelegate : NSObject <GoogleTestRunnerDelegate> {
   base::scoped_nsobject<UIWindow> _window;
 }
 - (void)runTests;
@@ -86,9 +91,12 @@ static char** g_argv;
     [self redirectOutput];
 
   // Queue up the test run.
-  [self performSelector:@selector(runTests)
-             withObject:nil
-             afterDelay:0.1];
+  if (!base::ShouldRunIOSUnittestsWithXCTest()) {
+    // When running in XCTest mode, XCTest will invoke |runGoogleTest| directly.
+    // Otherwise, schedule a call to |runTests|.
+    [self performSelector:@selector(runTests) withObject:nil afterDelay:0.1];
+  }
+
   return YES;
 }
 
@@ -150,7 +158,11 @@ static char** g_argv;
   }
 }
 
-- (void)runTests {
+- (BOOL)supportsRunningGoogleTests {
+  return base::ShouldRunIOSUnittestsWithXCTest();
+}
+
+- (int)runGoogleTests {
   coverage_util::ConfigureCoverageReportPath();
 
   int exitStatus = g_test_suite->Run();
@@ -158,6 +170,14 @@ static char** g_argv;
   if ([self shouldRedirectOutputToFile])
     [self writeOutputToNSLog];
 
+  return exitStatus;
+}
+
+- (void)runTests {
+  DCHECK(!base::ShouldRunIOSUnittestsWithXCTest());
+
+  int exitStatus = [self runGoogleTests];
+
   // If a test app is too fast, it will exit before Instruments has has a
   // a chance to initialize and no test results will be seen.
   // TODO(crbug.com/137010): Figure out how much time is actually needed, and
@@ -216,4 +236,9 @@ void RunTestsFromIOSApp() {
   }
 }
 
+bool ShouldRunIOSUnittestsWithXCTest() {
+  return base::CommandLine::ForCurrentProcess()->HasSwitch(
+      switches::kEnableRunIOSUnittestsWithXCTest);
+}
+
 }  // namespace base

base/test/test_switches.cc

@@ -84,3 +84,9 @@ const char switches::kTestLauncherTrace[] = "test-launcher-trace";
 const char switches::kTestTinyTimeout[] = "test-tiny-timeout";
 const char switches::kUiTestActionTimeout[] = "ui-test-action-timeout";
 const char switches::kUiTestActionMaxTimeout[] = "ui-test-action-max-timeout";
+
+#if defined(OS_IOS)
+// If enabled, runs unittests using the XCTest test runner.
+const char switches::kEnableRunIOSUnittestsWithXCTest[] =
+    "enable-run-ios-unittests-with-xctest";
+#endif

base/test/test_switches.h

@@ -5,6 +5,8 @@
 #ifndef BASE_TEST_TEST_SWITCHES_H_
 #define BASE_TEST_TEST_SWITCHES_H_
 
+#include "build/build_config.h"
+
 namespace switches {
 
 // All switches in alphabetical order. The switches should be documented
@@ -32,6 +34,10 @@ extern const char kTestTinyTimeout[];
 extern const char kUiTestActionTimeout[];
 extern const char kUiTestActionMaxTimeout[];
 
+#if defined(OS_IOS)
+extern const char kEnableRunIOSUnittestsWithXCTest[];
+#endif
+
 }  // namespace switches
 
 #endif  // BASE_TEST_TEST_SWITCHES_H_

build/config/ios/rules.gni

@@ -1808,13 +1808,20 @@ template("ios_xctest_test") {
   _host_target = _target_name
   _host_output = _output_name
 
-  _xctest_shell_source_target = _xctest_target + "shell_source"
-  source_set(_xctest_shell_source_target) {
-    sources = [
-      "//build/config/ios/xctest_shell.mm",
-    ]
+  # Allow invokers to specify their own target for the xctest module, but
+  # fall back to a default (empty) module otherwise.
+  if (defined(invoker.xctest_module_target)) {
+    _xctest_module_target = invoker.xctest_module_target
+  } else {
+    _xctest_module_target_name = _xctest_target + "shell_source"
+    _xctest_module_target = ":$_xctest_module_target_name"
+    source_set(_xctest_module_target_name) {
+      sources = [
+        "//build/config/ios/xctest_shell.mm",
+      ]
 
-    configs += [ "//build/config/ios:xctest_config" ]
+      configs += [ "//build/config/ios:xctest_config" ]
+    }
   }
 
   ios_xctest_bundle(_xctest_target) {
@@ -1824,7 +1831,7 @@ template("ios_xctest_test") {
     xcode_test_application_name = _host_output
 
     deps = [
-      ":$_xctest_shell_source_target",
+      _xctest_module_target,
     ]
   }
 

testing/test.gni

@@ -293,6 +293,14 @@ template("test") {
     import("//build/config/ios/ios_sdk.gni")
     import("//build/config/ios/rules.gni")
 
+    declare_args() {
+      # Keep the unittest-as-xctest functionality defaulted to off until the
+      # bots are updated to handle it properly.
+      # TODO(crbug.com/1001667): Remove this arg once the iOS test runner
+      # supports running unittests with xctest.
+      enable_run_ios_unittests_with_xctest = false
+    }
+
     _test_target = target_name
     _resources_bundle_data = target_name + "_resources_bundle_data"
 
@@ -306,9 +314,19 @@ template("test") {
       ]
     }
 
-    ios_app_bundle(_test_target) {
+    if (enable_run_ios_unittests_with_xctest) {
+      ios_test_target_type = "ios_xctest_test"
+    } else {
+      ios_test_target_type = "ios_app_bundle"
+    }
+
+    target(ios_test_target_type, _test_target) {
       testonly = true
 
+      if (enable_run_ios_unittests_with_xctest) {
+        xctest_module_target = "//base/test:google_test_runner"
+      }
+
       # See above call.
       set_sources_assignment_filter([])
       forward_variables_from(invoker, "*", [ "testonly" ])