[flutter_tools] Use process matcher for multidex test (#127996)

Part of https://github.com/flutter/flutter/issues/127135
Part of https://github.com/flutter/flutter/issues/125115

packages/flutter_tools/test/host_cross_arch.shard/cache_test.dart

@@ -32,10 +32,11 @@ HostPlatform _identifyMacBinaryArch(String path) {
     <String>['file', _dartBinary.path],
   );
   expect(
-      result,
-      ProcessResultMatcher(
-        stdoutSubstring: '${_dartBinary.path}: Mach-O 64-bit executable',
-      ));
+    result,
+    ProcessResultMatcher(
+      stdoutPattern: '${_dartBinary.path}: Mach-O 64-bit executable',
+    ),
+  );
   final RegExpMatch? match = pattern.firstMatch(result.stdout as String);
   if (match == null) {
     fail('Unrecognized STDOUT from `file`: "${result.stdout}"');

packages/flutter_tools/test/host_cross_arch.shard/ios_content_validation_test.dart

@@ -44,18 +44,22 @@ void main() {
       );
 
       // Pre-cache iOS engine Flutter.xcframework artifacts.
-      processManager.runSync(<String>[
-        flutterBin,
-        ...getLocalEngineArguments(),
-        'precache',
-        '--ios',
-      ], workingDirectory: tempDir.path);
+      ProcessResult result = processManager.runSync(
+        <String>[
+          flutterBin,
+          ...getLocalEngineArguments(),
+          'precache',
+          '--ios',
+        ],
+        workingDirectory: tempDir.path,
+      );
+      expect(result, const ProcessResultMatcher());
 
       // Pretend the SDK was on an external drive with stray "._" files in the xcframework
       hiddenFile = xcframeworkArtifact.childFile('._Info.plist')..createSync();
 
       // Test a plugin example app to allow plugins validation.
-      processManager.runSync(<String>[
+      result = processManager.runSync(<String>[
         flutterBin,
         ...getLocalEngineArguments(),
         'create',
@@ -65,6 +69,7 @@ void main() {
         'plugin',
         'hello',
       ], workingDirectory: tempDir.path);
+      expect(result, const ProcessResultMatcher());
 
       pluginRoot = tempDir.childDirectory('hello');
       projectRoot = pluginRoot.childDirectory('example').path;

packages/flutter_tools/test/integration.shard/analyze_all_templates_test.dart

@@ -9,6 +9,7 @@ import 'package:flutter_tools/src/globals.dart' as globals;
 import '../src/common.dart';
 import '../src/context.dart';
 import '../src/test_flutter_command_runner.dart';
+import 'test_utils.dart';
 
 void main() {
   group('pass analyze template:', () {
@@ -38,7 +39,7 @@ void main() {
         final ProcessResult result = await globals.processManager
             .run(<String>['flutter', 'analyze'], workingDirectory: projectPath);
 
-        expect(result.exitCode, 0);
+        expect(result, const ProcessResultMatcher());
       });
     }
   });

packages/flutter_tools/test/integration.shard/analyze_size_test.dart

@@ -30,10 +30,10 @@ void main() {
       '--target-platform=android-arm64',
     ], workingDirectory: workingDirectory);
 
-    printOnFailure('Output of flutter build apk:');
-    printOnFailure(result.stdout.toString());
-    printOnFailure(result.stderr.toString());
-    expect(result.stdout.toString(), contains('app-release.apk (total compressed)'));
+    expect(
+      result,
+      const ProcessResultMatcher(stdoutPattern: 'app-release.apk (total compressed)'),
+    );
 
     final String line = result.stdout.toString()
       .split('\n')
@@ -49,8 +49,6 @@ void main() {
     final String commandArguments = devToolsCommand.split(runDevToolsMessage).last.trim();
     final String relativeAppSizePath = outputFilePath.split('.flutter-devtools/').last.trim();
     expect(commandArguments.contains('--appSizeBase=$relativeAppSizePath'), isTrue);
-
-    expect(result.exitCode, 0);
   });
 
   testWithoutContext('--analyze-size flag produces expected output on hello_world for iOS', () async {
@@ -68,10 +66,10 @@ void main() {
       '--no-codesign',
     ], workingDirectory: workingDirectory);
 
-    printOnFailure('Output of flutter build ios:');
-    printOnFailure(result.stdout.toString());
-    printOnFailure(result.stderr.toString());
-    expect(result.stdout.toString(), contains('Dart AOT symbols accounted decompressed size'));
+    expect(
+      result,
+      const ProcessResultMatcher(stdoutPattern: 'Dart AOT symbols accounted decompressed size'),
+    );
 
     final String line = result.stdout.toString()
       .split('\n')
@@ -88,7 +86,6 @@ void main() {
 
     expect(commandArguments.contains('--appSizeBase=$relativeAppSizePath'), isTrue);
     expect(codeSizeDir.existsSync(), true);
-    expect(result.exitCode, 0);
     tempDir.deleteSync(recursive: true);
   }, skip: !platform.isMacOS); // [intended] iOS can only be built on macos.
 
@@ -105,6 +102,11 @@ void main() {
       '--enable-macos-desktop',
     ], workingDirectory: workingDirectory);
 
+    expect(
+      configResult,
+      const ProcessResultMatcher(),
+    );
+
     printOnFailure('Output of flutter config:');
     printOnFailure(configResult.stdout.toString());
     printOnFailure(configResult.stderr.toString());
@@ -117,10 +119,10 @@ void main() {
       '--code-size-directory=${codeSizeDir.path}',
     ], workingDirectory: workingDirectory);
 
-    printOnFailure('Output of flutter build macos:');
-    printOnFailure(result.stdout.toString());
-    printOnFailure(result.stderr.toString());
-    expect(result.stdout.toString(), contains('Dart AOT symbols accounted decompressed size'));
+    expect(
+      result,
+      const ProcessResultMatcher(stdoutPattern: 'Dart AOT symbols accounted decompressed size'),
+    );
 
     final String line = result.stdout.toString()
       .split('\n')
@@ -137,7 +139,6 @@ void main() {
 
     expect(commandArguments.contains('--appSizeBase=$relativeAppSizePath'), isTrue);
     expect(codeSizeDir.existsSync(), true);
-    expect(result.exitCode, 0);
     tempDir.deleteSync(recursive: true);
   }, skip: !platform.isMacOS); // [intended] this is a macos only test.
 
@@ -152,13 +153,13 @@ void main() {
       '--target-platform=android-arm64',
       '--debug',
     ], workingDirectory: fileSystem.path.join(getFlutterRoot(), 'examples', 'hello_world'));
-
-    printOnFailure('Output of flutter build apk:');
-    printOnFailure(result.stdout.toString());
-    printOnFailure(result.stderr.toString());
-    expect(result.stderr.toString(), contains('"--analyze-size" can only be used on release builds'));
-
-    expect(result.exitCode, 1);
+    expect(
+      result,
+      const ProcessResultMatcher(
+        exitCode: 1,
+        stderrPattern: '"--analyze-size" can only be used on release builds',
+      ),
+    );
   });
 
   testWithoutContext('--analyze-size is not supported in combination with --split-debug-info', () async {
@@ -177,14 +178,13 @@ void main() {
     final ProcessResult result =
         await processManager.run(command, workingDirectory: workingDirectory);
 
-    printOnFailure('workingDirectory: $workingDirectory');
-    printOnFailure('command:\n${command.join(" ")}');
-    printOnFailure('stdout:\n${result.stdout}');
-    printOnFailure('stderr:\n${result.stderr}');
-
-    expect(result.stderr.toString(), contains('"--analyze-size" cannot be combined with "--split-debug-info"'));
-
-    expect(result.exitCode, 1);
+    expect(
+      result,
+      const ProcessResultMatcher(
+        exitCode: 1,
+        stderrPattern: '"--analyze-size" cannot be combined with "--split-debug-info"',
+      ),
+    );
   });
 
   testWithoutContext('--analyze-size allows overriding the directory for code size files', () async {
@@ -211,15 +211,14 @@ void main() {
       workingDirectory: workingDirectory,
     );
 
-    printOnFailure('workingDirectory: $workingDirectory');
-    printOnFailure('command:\n${command.join(" ")}');
-    printOnFailure('stdout:\n${result.stdout}');
-    printOnFailure('stderr:\n${result.stderr}');
+    expect(
+      result,
+      const ProcessResultMatcher(),
+    );
 
-    expect(result.exitCode, 0);
-    expect(tempDir.existsSync(), true);
-    expect(tempDir.childFile('snapshot.arm64-v8a.json').existsSync(), true);
-    expect(tempDir.childFile('trace.arm64-v8a.json').existsSync(), true);
+    expect(tempDir, exists);
+    expect(tempDir.childFile('snapshot.arm64-v8a.json'), exists);
+    expect(tempDir.childFile('trace.arm64-v8a.json'), exists);
 
     tempDir.deleteSync(recursive: true);
   });

packages/flutter_tools/test/integration.shard/gradle_non_android_plugin_test.dart

@@ -79,7 +79,7 @@ void main() {
       '--verbose',
     ], workingDirectory: exampleDir.path);
 
-    expect(result, ProcessResultMatcher());
+    expect(result, const ProcessResultMatcher());
 
     final String exampleAppApk = fileSystem.path.join(
       exampleDir.path,

packages/flutter_tools/test/integration.shard/multidex_build_test.dart

@@ -36,8 +36,7 @@ void main() {
       '--debug',
     ], workingDirectory: tempDir.path);
 
-    expect(result.exitCode, 0);
-    expect(result.stdout.toString(), contains('app-debug.apk'));
+    expect(result, const ProcessResultMatcher(stdoutPattern: 'app-debug.apk'));
   });
 
   testWithoutContext('simple build apk without FlutterMultiDexApplication fails', () async {
@@ -52,8 +51,8 @@ void main() {
       '--debug',
     ], workingDirectory: tempDir.path);
 
+    expect(result, const ProcessResultMatcher(exitCode: 1));
     expect(result.stderr.toString(), contains('Cannot fit requested classes in a single dex file'));
     expect(result.stderr.toString(), contains('The number of method references in a .dex file cannot exceed 64K.'));
-    expect(result.exitCode, 1);
   });
 }

packages/flutter_tools/test/integration.shard/test_test.dart

@@ -32,21 +32,27 @@ final List<String> integrationTestExtraArgs = <String>['-d', 'flutter-tester'];
 
 void main() {
   setUpAll(() async {
-    await processManager.run(
-      <String>[
-        flutterBin,
-        'pub',
-        'get',
-      ],
-      workingDirectory: flutterTestDirectory
+    expect(
+      await processManager.run(
+        <String>[
+          flutterBin,
+          'pub',
+          'get',
+        ],
+        workingDirectory: flutterTestDirectory
+      ),
+      const ProcessResultMatcher(),
     );
-    await processManager.run(
-      <String>[
-        flutterBin,
-        'pub',
-        'get',
-      ],
-      workingDirectory: missingDependencyDirectory
+    expect(
+      await processManager.run(
+        <String>[
+          flutterBin,
+          'pub',
+          'get',
+        ],
+        workingDirectory: missingDependencyDirectory
+      ),
+      const ProcessResultMatcher(),
     );
   });
 
@@ -112,71 +118,109 @@ void main() {
   });
 
   testWithoutContext('flutter test should run a test when its name matches a regexp', () async {
-    final ProcessResult result = await _runFlutterTest('filtering', automatedTestsDirectory, flutterTestDirectory,
-      extraArguments: const <String>['--name', 'inc.*de']);
-    expect(result.stdout, contains(RegExp(r'\+\d+: All tests passed!')));
-    expect(result.exitCode, 0);
+    final ProcessResult result = await _runFlutterTest(
+      'filtering',
+      automatedTestsDirectory,
+      flutterTestDirectory,
+      extraArguments: const <String>['--name', 'inc.*de'],
+    );
+    expect(
+      result,
+      ProcessResultMatcher(stdoutPattern: RegExp(r'\+\d+: All tests passed!')),
+    );
   });
 
   testWithoutContext('flutter test should run a test when its name contains a string', () async {
-    final ProcessResult result = await _runFlutterTest('filtering', automatedTestsDirectory, flutterTestDirectory,
-      extraArguments: const <String>['--plain-name', 'include']);
-    expect(result.stdout, contains(RegExp(r'\+\d+: All tests passed!')));
-    expect(result.exitCode, 0);
+    final ProcessResult result = await _runFlutterTest(
+      'filtering',
+      automatedTestsDirectory,
+      flutterTestDirectory,
+      extraArguments: const <String>['--plain-name', 'include'],
+    );
+    expect(
+      result,
+      ProcessResultMatcher(stdoutPattern: RegExp(r'\+\d+: All tests passed!')),
+    );
   });
 
   testWithoutContext('flutter test should run a test with a given tag', () async {
-    final ProcessResult result = await _runFlutterTest('filtering_tag', automatedTestsDirectory, flutterTestDirectory,
-        extraArguments: const <String>['--tags', 'include-tag']);
-    expect(result.stdout, contains(RegExp(r'\+\d+: All tests passed!')));
-    expect(result.exitCode, 0);
+    final ProcessResult result = await _runFlutterTest(
+      'filtering_tag',
+      automatedTestsDirectory,
+      flutterTestDirectory,
+      extraArguments: const <String>['--tags', 'include-tag'],
+    );
+    expect(
+      result,
+      ProcessResultMatcher(stdoutPattern: RegExp(r'\+\d+: All tests passed!')),
+    );
   });
 
   testWithoutContext('flutter test should not run a test with excluded tag', () async {
     final ProcessResult result = await _runFlutterTest('filtering_tag', automatedTestsDirectory, flutterTestDirectory,
         extraArguments: const <String>['--exclude-tags', 'exclude-tag']);
-    expect(result.stdout, contains(RegExp(r'\+\d+: All tests passed!')));
-    expect(result.exitCode, 0);
+    expect(
+      result,
+      ProcessResultMatcher(stdoutPattern: RegExp(r'\+\d+: All tests passed!')),
+    );
   });
 
   testWithoutContext('flutter test should run all tests when tags are unspecified', () async {
     final ProcessResult result = await _runFlutterTest('filtering_tag', automatedTestsDirectory, flutterTestDirectory);
-    expect(result.stdout, contains(RegExp(r'\+\d+ -1: Some tests failed\.')));
-    expect(result.exitCode, 1);
+    expect(
+      result,
+      ProcessResultMatcher(
+        exitCode: 1,
+        stdoutPattern: RegExp(r'\+\d+ -1: Some tests failed\.'),
+      ),
+    );
   });
 
   testWithoutContext('flutter test should run a widgetTest with a given tag', () async {
     final ProcessResult result = await _runFlutterTest('filtering_tag_widget', automatedTestsDirectory, flutterTestDirectory,
         extraArguments: const <String>['--tags', 'include-tag']);
-    expect(result.stdout, contains(RegExp(r'\+\d+: All tests passed!')));
-    expect(result.exitCode, 0);
+    expect(
+      result,
+      ProcessResultMatcher(stdoutPattern: RegExp(r'\+\d+: All tests passed!')),
+    );
   });
 
   testWithoutContext('flutter test should not run a widgetTest with excluded tag', () async {
     final ProcessResult result = await _runFlutterTest('filtering_tag_widget', automatedTestsDirectory, flutterTestDirectory,
         extraArguments: const <String>['--exclude-tags', 'exclude-tag']);
-    expect(result.stdout, contains(RegExp(r'\+\d+: All tests passed!')));
-    expect(result.exitCode, 0);
+    expect(
+      result,
+      ProcessResultMatcher(stdoutPattern: RegExp(r'\+\d+: All tests passed!')),
+    );
   });
 
   testWithoutContext('flutter test should run all widgetTest when tags are unspecified', () async {
     final ProcessResult result = await _runFlutterTest('filtering_tag_widget', automatedTestsDirectory, flutterTestDirectory);
-    expect(result.stdout, contains(RegExp(r'\+\d+ -1: Some tests failed\.')));
-    expect(result.exitCode, 1);
+    expect(
+      result,
+      ProcessResultMatcher(
+        exitCode: 1,
+        stdoutPattern: RegExp(r'\+\d+ -1: Some tests failed\.'),
+      ),
+    );
   });
 
   testWithoutContext('flutter test should run a test with an exact name in URI format', () async {
     final ProcessResult result = await _runFlutterTest('uri_format', automatedTestsDirectory, flutterTestDirectory,
       query: 'full-name=exactTestName');
-    expect(result.stdout, contains(RegExp(r'\+\d+: All tests passed!')));
-    expect(result.exitCode, 0);
+    expect(
+      result,
+      ProcessResultMatcher(stdoutPattern: RegExp(r'\+\d+: All tests passed!')),
+    );
   });
 
   testWithoutContext('flutter test should run a test by line number in URI format', () async {
     final ProcessResult result = await _runFlutterTest('uri_format', automatedTestsDirectory, flutterTestDirectory,
       query: 'line=11');
-    expect(result.stdout, contains(RegExp(r'\+\d+: All tests passed!')));
-    expect(result.exitCode, 0);
+    expect(
+      result,
+      ProcessResultMatcher(stdoutPattern: RegExp(r'\+\d+: All tests passed!')),
+    );
   });
 
   testWithoutContext('flutter test should test runs to completion', () async {
@@ -214,8 +258,8 @@ void main() {
   });
 
   testWithoutContext('flutter test should respect --serve-observatory', () async {
-    late final Process process;
-    late final StreamSubscription<String> sub;
+    Process? process;
+    StreamSubscription<String>? sub;
     try {
       process = await _runFlutterTestConcurrent('trivial', automatedTestsDirectory, flutterTestDirectory,
         extraArguments: const <String>['--start-paused', '--serve-observatory']);
@@ -231,16 +275,16 @@ void main() {
       final HttpClientRequest request = await client.getUrl(vmServiceUri);
       final HttpClientResponse response = await request.close();
       final String content = await response.transform(utf8.decoder).join();
-      expect(content.contains('Dart VM Observatory'), true);
+      expect(content, contains('Dart VM Observatory'));
     } finally {
-      await sub.cancel();
-      process.kill();
+      await sub?.cancel();
+      process?.kill();
     }
   });
 
   testWithoutContext('flutter test should serve DevTools', () async {
-    late final Process process;
-    late final StreamSubscription<String> sub;
+    Process? process;
+    StreamSubscription<String>? sub;
     try {
       process = await _runFlutterTestConcurrent('trivial', automatedTestsDirectory, flutterTestDirectory,
         extraArguments: const <String>['--start-paused']);
@@ -256,10 +300,10 @@ void main() {
       final HttpClientRequest request = await client.getUrl(devToolsUri);
       final HttpClientResponse response = await request.close();
       final String content = await response.transform(utf8.decoder).join();
-      expect(content.contains('DevTools'), true);
+      expect(content, contains('DevTools'));
     } finally {
-      await sub.cancel();
-      process.kill();
+      await sub?.cancel();
+      process?.kill();
     }
   });
 }
@@ -285,7 +329,12 @@ Future<void> _testFile(
     extraArguments: extraArguments,
   );
 
-  expect(exec.exitCode, exitCode);
+  expect(
+    exec.exitCode,
+    exitCode,
+    reason: '"$testName" returned code ${exec.exitCode}\n\nstdout:\n'
+            '${exec.stdout}\nstderr:\n${exec.stderr}',
+  );
   final List<String> output = (exec.stdout as String).split('\n');
   if (output.first.startsWith('Waiting for another flutter command to release the startup lock...')) {
     output.removeAt(0);

packages/flutter_tools/test/integration.shard/test_utils.dart

@@ -128,35 +128,32 @@ abstract final class AppleTestUtils {
 /// Matcher to be used for [ProcessResult] returned
 /// from a process run
 ///
-/// The default for [expectedExitCode] will be 0 while
-/// [stdoutSubstring] and [stderrSubstring] are both optional
+/// The default for [exitCode] will be 0 while
+/// [stdoutPattern] and [stderrPattern] are both optional
 class ProcessResultMatcher extends Matcher {
-  ProcessResultMatcher({
-    this.expectedExitCode = 0,
-    this.stdoutSubstring,
-    this.stderrSubstring,
+  const ProcessResultMatcher({
+    this.exitCode = 0,
+    this.stdoutPattern,
+    this.stderrPattern,
   });
 
   /// The expected exit code to get returned from a process run
-  final int expectedExitCode;
+  final int exitCode;
 
   /// Substring to find in the process's stdout
-  final String? stdoutSubstring;
+  final Pattern? stdoutPattern;
 
   /// Substring to find in the process's stderr
-  final String? stderrSubstring;
-
-  bool _foundStdout = true;
-  bool _foundStderr = true;
+  final Pattern? stderrPattern;
 
   @override
   Description describe(Description description) {
-    description.add('a process with exit code $expectedExitCode');
-    if (stdoutSubstring != null) {
-      description.add(' and stdout: "$stdoutSubstring"');
+    description.add('a process with exit code $exitCode');
+    if (stdoutPattern != null) {
+      description.add(' and stdout: "$stdoutPattern"');
     }
-    if (stderrSubstring != null) {
-      description.add(' and stderr: "$stderrSubstring"');
+    if (stderrPattern != null) {
+      description.add(' and stderr: "$stderrPattern"');
     }
 
     return description;
@@ -165,18 +162,27 @@ class ProcessResultMatcher extends Matcher {
   @override
   bool matches(dynamic item, Map<dynamic, dynamic> matchState) {
     final ProcessResult result = item as ProcessResult;
-
-    if (stdoutSubstring != null) {
-      _foundStdout = (result.stdout as String).contains(stdoutSubstring!);
-      matchState['stdout'] = result.stdout;
+    bool foundStdout = true;
+    bool foundStderr = true;
+
+    final String stdout = result.stdout as String;
+    final String stderr = result.stderr as String;
+    if (stdoutPattern != null) {
+      foundStdout = stdout.contains(stdoutPattern!);
+      matchState['stdout'] = stdout;
+    } else if (stdout.isNotEmpty) {
+      // even if we were not asserting on stdout, show stdout for debug purposes
+      matchState['stdout'] = stdout;
     }
 
-    if (stderrSubstring != null) {
-      _foundStderr = (result.stderr as String).contains(stderrSubstring!);
-      matchState['stderr'] = result.stderr;
+    if (stderrPattern != null) {
+      foundStderr = stderr.contains(stderrPattern!);
+      matchState['stderr'] = stderr;
+    } else if (stderr.isNotEmpty) {
+      matchState['stderr'] = stderr;
     }
 
-    return result.exitCode == expectedExitCode && _foundStdout && _foundStderr;
+    return result.exitCode == exitCode && foundStdout && foundStderr;
   }
 
   @override
@@ -188,16 +194,16 @@ class ProcessResultMatcher extends Matcher {
   ) {
     final ProcessResult result = item! as ProcessResult;
 
-    if (result.exitCode != expectedExitCode) {
-      mismatchDescription.add('Actual exitCode was ${result.exitCode}');
+    if (result.exitCode != exitCode) {
+      mismatchDescription.add('Actual exitCode was ${result.exitCode}\n');
     }
 
     if (matchState.containsKey('stdout')) {
-      mismatchDescription.add('Actual stdout:\n${matchState["stdout"]}');
+      mismatchDescription.add('Actual stdout:\n${matchState["stdout"]}\n');
     }
 
     if (matchState.containsKey('stderr')) {
-      mismatchDescription.add('Actual stderr:\n${matchState["stderr"]}');
+      mismatchDescription.add('Actual stderr:\n${matchState["stderr"]}\n');
     }
 
     return mismatchDescription;

packages/flutter_tools/test/integration.shard/tool_backend_test.dart

@@ -20,8 +20,13 @@ void main() {
       'debug',
     ]);
 
-    expect(result.exitCode, 1);
-    expect(result.stderr, contains('PROJECT_DIR environment variable must be set to the location of Flutter project to be built.'));
+    expect(
+      result,
+      const ProcessResultMatcher(
+        exitCode: 1,
+        stderrPattern: 'PROJECT_DIR environment variable must be set to the location of Flutter project to be built.',
+      ),
+    );
   });
 
   testWithoutContext('tool_backend.dart exits if FLUTTER_ROOT is not set', () async {
@@ -37,8 +42,13 @@ void main() {
       'PROJECT_DIR': examplePath,
     }, includeParentEnvironment: false); // Prevent FLUTTER_ROOT set by test environment from leaking
 
-    expect(result.exitCode, 1);
-    expect(result.stderr, contains('FLUTTER_ROOT environment variable must be set to the location of the Flutter SDK.'));
+    expect(
+      result,
+      const ProcessResultMatcher(
+        exitCode: 1,
+        stderrPattern: 'FLUTTER_ROOT environment variable must be set to the location of the Flutter SDK.',
+      ),
+    );
   });
 
   testWithoutContext('tool_backend.dart exits if local engine does not match build mode', () async {
@@ -52,7 +62,12 @@ void main() {
       'LOCAL_ENGINE': 'release_foo_bar', // Does not contain "debug",
     });
 
-    expect(result.exitCode, 1);
-    expect(result.stderr, contains("ERROR: Requested build with Flutter local engine at 'release_foo_bar'"));
+    expect(
+      result,
+      const ProcessResultMatcher(
+        exitCode: 1,
+        stderrPattern: "ERROR: Requested build with Flutter local engine at 'release_foo_bar'",
+      ),
+    );
   });
 }