hasStrings Mac (flutter/engine#20531)

Adds the hasStrings method for Mac, and improves the state of unit testing on Mac.

engine/src/flutter/ci/licenses_golden/licenses_flutter

@@ -1035,6 +1035,7 @@ FILE: ../../../flutter/shell/platform/darwin/macos/framework/Source/FlutterTextI
 FILE: ../../../flutter/shell/platform/darwin/macos/framework/Source/FlutterView.h
 FILE: ../../../flutter/shell/platform/darwin/macos/framework/Source/FlutterView.mm
 FILE: ../../../flutter/shell/platform/darwin/macos/framework/Source/FlutterViewController.mm
+FILE: ../../../flutter/shell/platform/darwin/macos/framework/Source/FlutterViewControllerTest.mm
 FILE: ../../../flutter/shell/platform/darwin/macos/framework/Source/FlutterViewController_Internal.h
 FILE: ../../../flutter/shell/platform/darwin/macos/framework/Source/fixtures/flutter_desktop_test.dart
 FILE: ../../../flutter/shell/platform/darwin/macos/framework/module.modulemap

engine/src/flutter/shell/platform/darwin/macos/BUILD.gn

@@ -101,7 +101,10 @@ test_fixtures("flutter_desktop_darwin_fixtures") {
 executable("flutter_desktop_darwin_unittests") {
   testonly = true
 
-  sources = [ "framework/Source/FlutterEngineUnittests.mm" ]
+  sources = [
+    "framework/Source/FlutterEngineUnittests.mm",
+    "framework/Source/FlutterViewControllerTest.mm",
+  ]
 
   cflags_objcc = [ "-fobjc-arc" ]
 
@@ -114,6 +117,7 @@ executable("flutter_desktop_darwin_unittests") {
     "//flutter/testing:dart",
     "//flutter/testing:skia",
     "//flutter/testing:testing_lib",
+    "//third_party/ocmock:ocmock",
   ]
 }
 

engine/src/flutter/shell/platform/darwin/macos/framework/Source/FlutterViewController.mm

@@ -173,6 +173,11 @@ struct KeyboardState {
  */
 - (void)setClipboardData:(NSDictionary*)data;
 
+/**
+ * Returns true iff the clipboard contains nonempty string data.
+ */
+- (BOOL)clipboardHasStrings;
+
 @end
 
 #pragma mark - FlutterViewController implementation.
@@ -505,6 +510,8 @@ static void CommonInit(FlutterViewController* controller) {
   } else if ([call.method isEqualToString:@"Clipboard.setData"]) {
     [self setClipboardData:call.arguments];
     result(nil);
+  } else if ([call.method isEqualToString:@"Clipboard.hasStrings"]) {
+    result(@{@"value" : @([self clipboardHasStrings])});
   } else {
     result(FlutterMethodNotImplemented);
   }
@@ -517,7 +524,7 @@ static void CommonInit(FlutterViewController* controller) {
 }
 
 - (NSDictionary*)getClipboardData:(NSString*)format {
-  NSPasteboard* pasteboard = [NSPasteboard generalPasteboard];
+  NSPasteboard* pasteboard = self.pasteboard;
   if ([format isEqualToString:@(kTextPlainFormat)]) {
     NSString* stringInPasteboard = [pasteboard stringForType:NSPasteboardTypeString];
     return stringInPasteboard == nil ? nil : @{@"text" : stringInPasteboard};
@@ -526,14 +533,22 @@ static void CommonInit(FlutterViewController* controller) {
 }
 
 - (void)setClipboardData:(NSDictionary*)data {
-  NSPasteboard* pasteboard = [NSPasteboard generalPasteboard];
+  NSPasteboard* pasteboard = self.pasteboard;
   NSString* text = data[@"text"];
+  [pasteboard clearContents];
   if (text && ![text isEqual:[NSNull null]]) {
-    [pasteboard clearContents];
     [pasteboard setString:text forType:NSPasteboardTypeString];
   }
 }
 
+- (BOOL)clipboardHasStrings {
+  return [self.pasteboard stringForType:NSPasteboardTypeString].length > 0;
+}
+
+- (NSPasteboard*)pasteboard {
+  return [NSPasteboard generalPasteboard];
+}
+
 #pragma mark - FlutterViewReshapeListener
 
 /**

engine/src/flutter/shell/platform/darwin/macos/framework/Source/FlutterViewControllerTest.mm

@@ -0,0 +1,75 @@
+// Copyright 2013 The Flutter 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 "flutter/shell/platform/darwin/macos/framework/Source/FlutterViewController_Internal.h"
+
+#include "flutter/shell/platform/darwin/macos/framework/Headers/FlutterEngine.h"
+#include "flutter/shell/platform/darwin/macos/framework/Source/FlutterDartProject_Internal.h"
+#include "flutter/shell/platform/darwin/macos/framework/Source/FlutterEngine_Internal.h"
+#include "flutter/testing/testing.h"
+#import "third_party/ocmock/Source/OCMock/OCMock.h"
+
+namespace flutter::testing {
+
+// Returns a mock FlutterViewController that is able to work in environments
+// without a real pasteboard.
+id mockViewController(NSString* pasteboardString) {
+  NSString* fixtures = @(testing::GetFixturesPath());
+  FlutterDartProject* project = [[FlutterDartProject alloc]
+      initWithAssetsPath:fixtures
+             ICUDataPath:[fixtures stringByAppendingString:@"/icudtl.dat"]];
+  FlutterViewController* viewController = [[FlutterViewController alloc] initWithProject:project];
+
+  // Mock pasteboard so that this test will work in environments without a
+  // real pasteboard.
+  id pasteboardMock = OCMClassMock([NSPasteboard class]);
+  OCMExpect([pasteboardMock stringForType:[OCMArg any]]).andDo(^(NSInvocation* invocation) {
+    NSString* returnValue = pasteboardString.length > 0 ? pasteboardString : nil;
+    [invocation setReturnValue:&returnValue];
+  });
+  id viewControllerMock = OCMPartialMock(viewController);
+  OCMStub([viewControllerMock pasteboard]).andReturn(pasteboardMock);
+  return viewControllerMock;
+}
+
+TEST(FlutterViewControllerTest, HasStringsWhenPasteboardEmpty) {
+  // Mock FlutterViewController so that it behaves like the pasteboard is empty.
+  id viewControllerMock = mockViewController(nil);
+
+  // Call hasStrings and expect it to be false.
+  __block bool calledAfterClear = false;
+  __block bool valueAfterClear;
+  FlutterResult resultAfterClear = ^(id result) {
+    calledAfterClear = true;
+    NSNumber* valueNumber = [result valueForKey:@"value"];
+    valueAfterClear = [valueNumber boolValue];
+  };
+  FlutterMethodCall* methodCallAfterClear =
+      [FlutterMethodCall methodCallWithMethodName:@"Clipboard.hasStrings" arguments:nil];
+  [viewControllerMock handleMethodCall:methodCallAfterClear result:resultAfterClear];
+  ASSERT_TRUE(calledAfterClear);
+  ASSERT_FALSE(valueAfterClear);
+}
+
+TEST(FlutterViewControllerTest, HasStringsWhenPasteboardFull) {
+  // Mock FlutterViewController so that it behaves like the pasteboard has a
+  // valid string.
+  id viewControllerMock = mockViewController(@"some string");
+
+  // Call hasStrings and expect it to be true.
+  __block bool called = false;
+  __block bool value;
+  FlutterResult result = ^(id result) {
+    called = true;
+    NSNumber* valueNumber = [result valueForKey:@"value"];
+    value = [valueNumber boolValue];
+  };
+  FlutterMethodCall* methodCall =
+      [FlutterMethodCall methodCallWithMethodName:@"Clipboard.hasStrings" arguments:nil];
+  [viewControllerMock handleMethodCall:methodCall result:result];
+  ASSERT_TRUE(called);
+  ASSERT_TRUE(value);
+}
+
+}  // flutter::testing

engine/src/flutter/shell/platform/darwin/macos/framework/Source/FlutterViewController_Internal.h

@@ -11,6 +11,11 @@
 // The FlutterView for this view controller.
 @property(nonatomic, readonly, nullable) FlutterView* flutterView;
 
+/**
+ * This just returns the NSPasteboard so that it can be mocked in the tests.
+ */
+@property(nonatomic, readonly, nonnull) NSPasteboard* pasteboard;
+
 /**
  * Adds a responder for keyboard events. Key up and key down events are forwarded to all added
  * responders.