[flutter_tools] remove mocks from file system test (#74919)

packages/flutter_tools/test/general.shard/base/file_system_test.dart

diff --git a/packages/flutter_tools/test/general.shard/base/file_system_test.dart b/packages/flutter_tools/test/general.shard/base/file_system_test.dart
index b16451b..6c32524 100644
--- a/packages/flutter_tools/test/general.shard/base/file_system_test.dart
+++ b/packages/flutter_tools/test/general.shard/base/file_system_test.dart
@@ -12,7 +12,7 @@
 import 'package:flutter_tools/src/base/io.dart';
 import 'package:flutter_tools/src/base/platform.dart';
 import 'package:flutter_tools/src/base/signals.dart';
-import 'package:mockito/mockito.dart';
+import 'package:test/fake.dart';
 
 import '../../src/common.dart';
 import '../../src/context.dart';
@@ -147,15 +147,12 @@
   });
 
   group('LocalFileSystem', () {
-    MockIoProcessSignal mockSignal;
+    FakeProcessSignal fakeSignal;
     ProcessSignal signalUnderTest;
-    StreamController<io.ProcessSignal> controller;
 
     setUp(() {
-      mockSignal = MockIoProcessSignal();
-      signalUnderTest = ProcessSignal(mockSignal);
-      controller = StreamController<io.ProcessSignal>();
-      when(mockSignal.watch()).thenAnswer((Invocation invocation) => controller.stream);
+      fakeSignal = FakeProcessSignal();
+      signalUnderTest = ProcessSignal(fakeSignal);
     });
 
     testUsingContext('deletes system temp entry on a fatal signal', () async {
@@ -173,7 +170,7 @@
 
       expect(temp.existsSync(), isTrue);
 
-      controller.add(mockSignal);
+      fakeSignal.controller.add(fakeSignal);
       await completer.future;
 
       expect(temp.existsSync(), isFalse);
@@ -181,5 +178,10 @@
   });
 }
 
-class MockIoProcessSignal extends Mock implements io.ProcessSignal {}
-class MockFile extends Mock implements File {}
+class FakeProcessSignal extends Fake implements io.ProcessSignal {
+  final StreamController<io.ProcessSignal> controller = StreamController<io.ProcessSignal>();
+
+  @override
+  Stream<io.ProcessSignal> watch() => controller.stream;
+}
+class FakeFile extends Fake implements File {}

packages/flutter_tools/test/general.shard/base/io_test.dart

diff --git a/packages/flutter_tools/test/general.shard/base/io_test.dart b/packages/flutter_tools/test/general.shard/base/io_test.dart
index 375a8cf..6185bc4 100644
--- a/packages/flutter_tools/test/general.shard/base/io_test.dart
+++ b/packages/flutter_tools/test/general.shard/base/io_test.dart
@@ -9,7 +9,7 @@
 
 import 'package:file/memory.dart';
 import 'package:flutter_tools/src/base/io.dart';
-import 'package:mockito/mockito.dart';
+import 'package:test/fake.dart';
 
 import '../../src/common.dart';
 import '../../src/context.dart';
@@ -57,12 +57,10 @@
     }, flutterIOOverrides);
   });
   testUsingContext('ProcessSignal signals are properly delegated', () async {
-    final MockIoProcessSignal mockSignal = MockIoProcessSignal();
-    final ProcessSignal signalUnderTest = ProcessSignal(mockSignal);
-    final StreamController<io.ProcessSignal> controller = StreamController<io.ProcessSignal>();
+    final FakeProcessSignal signal = FakeProcessSignal();
+    final ProcessSignal signalUnderTest = ProcessSignal(signal);
 
-    when(mockSignal.watch()).thenAnswer((Invocation invocation) => controller.stream);
-    controller.add(mockSignal);
+    signal.controller.add(signal);
 
     expect(signalUnderTest, await signalUnderTest.watch().first);
   });
@@ -104,4 +102,9 @@
   });
 }
 
-class MockIoProcessSignal extends Mock implements io.ProcessSignal {}
+class FakeProcessSignal extends Fake implements io.ProcessSignal {
+  final StreamController<io.ProcessSignal> controller = StreamController<io.ProcessSignal>();
+
+  @override
+  Stream<io.ProcessSignal> watch() => controller.stream;
+}

packages/flutter_tools/test/general.shard/base/signals_test.dart

diff --git a/packages/flutter_tools/test/general.shard/base/signals_test.dart b/packages/flutter_tools/test/general.shard/base/signals_test.dart
index 11d5653..3e45e73 100644
--- a/packages/flutter_tools/test/general.shard/base/signals_test.dart
+++ b/packages/flutter_tools/test/general.shard/base/signals_test.dart
@@ -16,16 +16,13 @@
 void main() {
   group('Signals', () {
     Signals signals;
-    MockIoProcessSignal mockSignal;
+    FakeProcessSignal fakeSignal;
     ProcessSignal signalUnderTest;
-    StreamController<io.ProcessSignal> controller;
 
     setUp(() {
       signals = Signals.test();
-      mockSignal = MockIoProcessSignal();
-      signalUnderTest = ProcessSignal(mockSignal);
-      controller = StreamController<io.ProcessSignal>();
-      when(mockSignal.watch()).thenAnswer((Invocation invocation) => controller.stream);
+      fakeSignal = FakeProcessSignal();
+      signalUnderTest = ProcessSignal(fakeSignal);
     });
 
     testWithoutContext('signal handler runs', () async {
@@ -35,7 +32,7 @@
         completer.complete();
       });
 
-      controller.add(mockSignal);
+      fakeSignal.controller.add(fakeSignal);
       await completer.future;
     });
 
@@ -55,7 +52,7 @@
         completer.complete();
       });
 
-      controller.add(mockSignal);
+      fakeSignal.controller.add(fakeSignal);
       await completer.future;
     });
 
@@ -74,7 +71,7 @@
         },
       );
 
-      controller.add(mockSignal);
+      fakeSignal.controller.add(fakeSignal);
       await completer.future;
       await errSub.cancel();
       expect(errList, contains(exn));
@@ -97,7 +94,7 @@
         },
       );
 
-      controller.add(mockSignal);
+      fakeSignal.controller.add(fakeSignal);
 
       await errSub.cancel();
       expect(errList, isEmpty);
@@ -125,19 +122,16 @@
         },
       );
 
-      controller.add(mockSignal);
+      fakeSignal.controller.add(fakeSignal);
       await completer.future;
       await errSub.cancel();
       expect(errList, isEmpty);
     });
 
     testWithoutContext('only handlers for the correct signal run', () async {
-      final MockIoProcessSignal mockSignal2 = MockIoProcessSignal();
-      final StreamController<io.ProcessSignal> controller2 = StreamController<io.ProcessSignal>();
+      final FakeProcessSignal mockSignal2 = FakeProcessSignal();
       final ProcessSignal otherSignal = ProcessSignal(mockSignal2);
 
-      when(mockSignal2.watch()).thenAnswer((Invocation invocation) => controller2.stream);
-
       final Completer<void> completer = Completer<void>();
       signals.addHandler(signalUnderTest, (ProcessSignal s) {
         expect(s, signalUnderTest);
@@ -155,7 +149,7 @@
         },
       );
 
-      controller.add(mockSignal);
+      fakeSignal.controller.add(fakeSignal);
       await completer.future;
       await errSub.cancel();
       expect(errList, isEmpty);
@@ -192,10 +186,15 @@
         second = true;
       });
 
-      controller.add(mockSignal);
+      fakeSignal.controller.add(fakeSignal);
       await completer.future;
     });
   });
 }
 
-class MockIoProcessSignal extends Mock implements io.ProcessSignal {}
+class FakeProcessSignal extends Fake implements io.ProcessSignal {
+  final StreamController<io.ProcessSignal> controller = StreamController<io.ProcessSignal>();
+
+  @override
+  Stream<io.ProcessSignal> watch() => controller.stream;
+}