Make the SwiftPM integration tests more idiomatic (#157971)

I recommend reviewing with [whitespace changes disabled](https://github.com/flutter/flutter/pull/157971/files?diff=split&w=1).

Changes:

1. Replaces `expect(string.contains('foo'), isTrue)` with `expect(string, contains('foo'))`
2. Replaces `try/finally` with `addTearDown`

Follow-up to: https://github.com/flutter/flutter/pull/157482#discussion_r1813939657

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

@@ -29,7 +29,15 @@ void main() {
         final Directory workingDirectory = fileSystem.systemTempDirectory
             .createTempSync('swift_package_manager_enabled.');
         final String workingDirectoryPath = workingDirectory.path;
-        try {
+
+        addTearDown(() async {
+          await SwiftPackageManagerUtils.disableSwiftPackageManager(flutterBin, workingDirectoryPath);
+          ErrorHandlingFileSystem.deleteIfExists(
+            workingDirectory,
+            recursive: true,
+          );
+        });
+
         // Create and build an app using the CocoaPods version of
         // integration_test.
         await SwiftPackageManagerUtils.disableSwiftPackageManager(flutterBin, workingDirectoryPath);
@@ -212,13 +220,6 @@ void main() {
             cocoaPodsPlugin: integrationTestPlugin,
           ),
         );
-        } finally {
-          await SwiftPackageManagerUtils.disableSwiftPackageManager(flutterBin, workingDirectoryPath);
-          ErrorHandlingFileSystem.deleteIfExists(
-            workingDirectory,
-            recursive: true,
-          );
-        }
       }, skip: !platform.isMacOS); // [intended] Swift Package Manager only works on macos.
     }
 
@@ -226,7 +227,15 @@ void main() {
       final Directory workingDirectory = fileSystem.systemTempDirectory
           .createTempSync('swift_package_manager_build_framework.');
       final String workingDirectoryPath = workingDirectory.path;
-      try {
+
+      addTearDown(() async {
+        await SwiftPackageManagerUtils.disableSwiftPackageManager(flutterBin, workingDirectoryPath);
+        ErrorHandlingFileSystem.deleteIfExists(
+          workingDirectory,
+          recursive: true,
+        );
+      });
+
       // Create and build an app using the Swift Package Manager version of
       // integration_test.
       await SwiftPackageManagerUtils.enableSwiftPackageManager(flutterBin, workingDirectoryPath);
@@ -294,20 +303,21 @@ void main() {
           .existsSync(),
         isTrue,
       );
-      } finally {
-        await SwiftPackageManagerUtils.disableSwiftPackageManager(flutterBin, workingDirectoryPath);
-        ErrorHandlingFileSystem.deleteIfExists(
-          workingDirectory,
-          recursive: true,
-        );
-      }
     }, skip: !platform.isMacOS); // [intended] Swift Package Manager only works on macos.
 
     test('Caches build targets between builds with Swift Package Manager on $platformName', () async {
       final Directory workingDirectory = fileSystem.systemTempDirectory
         .createTempSync('swift_package_manager_caching.');
       final String workingDirectoryPath = workingDirectory.path;
-        try {
+
+      addTearDown(() async {
+        await SwiftPackageManagerUtils.disableSwiftPackageManager(flutterBin, workingDirectoryPath);
+        ErrorHandlingFileSystem.deleteIfExists(
+          workingDirectory,
+          recursive: true,
+        );
+      });
+
       // Create and build an app using the Swift Package Manager version of
       // integration_test.
       await SwiftPackageManagerUtils.enableSwiftPackageManager(flutterBin, workingDirectoryPath);
@@ -362,14 +372,6 @@ void main() {
           'Starting due to',
         ],
       );
-
-        } finally {
-          await SwiftPackageManagerUtils.disableSwiftPackageManager(flutterBin, workingDirectoryPath);
-          ErrorHandlingFileSystem.deleteIfExists(
-            workingDirectory,
-            recursive: true,
-          );
-        }
     }, skip: !platform.isMacOS); // [intended] Swift Package Manager only works on macos.
   }
 
@@ -377,7 +379,15 @@ void main() {
     final Directory workingDirectory = fileSystem.systemTempDirectory
         .createTempSync('swift_package_manager_build_framework_module.');
     final String workingDirectoryPath = workingDirectory.path;
-    try {
+
+    addTearDown(() async {
+      await SwiftPackageManagerUtils.disableSwiftPackageManager(flutterBin, workingDirectoryPath);
+      ErrorHandlingFileSystem.deleteIfExists(
+        workingDirectory,
+        recursive: true,
+      );
+    });
+
     // Create and build module and framework using the CocoaPods version of
     // integration_test even though Swift Package Manager is enabled.
     await SwiftPackageManagerUtils.enableSwiftPackageManager(flutterBin, workingDirectoryPath);
@@ -425,8 +435,8 @@ void main() {
       .childFile('project.pbxproj');
     expect(pbxprojFile.existsSync(), isTrue);
     expect(
-        pbxprojFile.readAsStringSync().contains('FlutterGeneratedPluginSwiftPackage'),
+      pbxprojFile.readAsStringSync(),
-        isFalse,
+      isNot(contains('FlutterGeneratedPluginSwiftPackage')),
     );
     final File xcschemeFile = fileSystem
       .directory(appDirectoryPath)
@@ -437,8 +447,8 @@ void main() {
       .childFile('Runner.xcscheme');
     expect(xcschemeFile.existsSync(), isTrue);
     expect(
-        xcschemeFile.readAsStringSync().contains('Run Prepare Flutter Framework Script'),
+      xcschemeFile.readAsStringSync(),
-        isFalse,
+      isNot(contains('Run Prepare Flutter Framework Script')),
     );
 
     await SwiftPackageManagerUtils.buildApp(
@@ -467,20 +477,21 @@ void main() {
         .existsSync(),
       isTrue,
     );
-    } finally {
-      await SwiftPackageManagerUtils.disableSwiftPackageManager(flutterBin, workingDirectoryPath);
-      ErrorHandlingFileSystem.deleteIfExists(
-        workingDirectory,
-        recursive: true,
-      );
-    }
   }, skip: !platform.isMacOS); // [intended] Swift Package Manager only works on macos.
 
   test('Build ios-framework with non module app uses CocoaPods', () async {
     final Directory workingDirectory = fileSystem.systemTempDirectory
       .createTempSync('swift_package_manager_build_framework_non_module.');
     final String workingDirectoryPath = workingDirectory.path;
-    try {
+
+    addTearDown(() async {
+      await SwiftPackageManagerUtils.disableSwiftPackageManager(flutterBin, workingDirectoryPath);
+      ErrorHandlingFileSystem.deleteIfExists(
+        workingDirectory,
+        recursive: true,
+      );
+    });
+
     // Create and build a regular app and framework using the CocoaPods version of
     // integration_test even though Swift Package Manager is enabled.
     await SwiftPackageManagerUtils.enableSwiftPackageManager(flutterBin, workingDirectoryPath);
@@ -563,20 +574,21 @@ void main() {
       flutterPluginsDependenciesFile.readAsStringSync(),
       contains('"swift_package_manager_enabled":false'),
     );
-    } finally {
-      await SwiftPackageManagerUtils.disableSwiftPackageManager(flutterBin, workingDirectoryPath);
-      ErrorHandlingFileSystem.deleteIfExists(
-        workingDirectory,
-        recursive: true,
-      );
-    }
   }, skip: !platform.isMacOS); // [intended] Swift Package Manager only works on macos.
 
   test("Generated Swift package uses iOS's project minimum deployment", () async {
     final Directory workingDirectory = fileSystem.systemTempDirectory
       .createTempSync('swift_package_manager_minimum_deployment_ios.');
     final String workingDirectoryPath = workingDirectory.path;
-    try {
+
+    addTearDown(() async {
+      await SwiftPackageManagerUtils.disableSwiftPackageManager(flutterBin, workingDirectoryPath);
+      ErrorHandlingFileSystem.deleteIfExists(
+        workingDirectory,
+        recursive: true,
+      );
+    });
+
     await SwiftPackageManagerUtils.enableSwiftPackageManager(flutterBin, workingDirectoryPath);
     final String appDirectoryPath = await SwiftPackageManagerUtils.createApp(
       flutterBin,
@@ -629,20 +641,21 @@ void main() {
 ''';
 
     expect(generatedManifest.contains(expected), isTrue);
-    } finally {
-      await SwiftPackageManagerUtils.disableSwiftPackageManager(flutterBin, workingDirectoryPath);
-      ErrorHandlingFileSystem.deleteIfExists(
-        workingDirectory,
-        recursive: true,
-      );
-    }
   }, skip: !platform.isMacOS); // [intended] Swift Package Manager only works on macos.
 
   test("Generated Swift package uses macOS's project minimum deployment", () async {
     final Directory workingDirectory = fileSystem.systemTempDirectory
       .createTempSync('swift_package_manager_minimum_deployment_macos.');
     final String workingDirectoryPath = workingDirectory.path;
-    try {
+
+    addTearDown(() async {
+      await SwiftPackageManagerUtils.disableSwiftPackageManager(flutterBin, workingDirectoryPath);
+      ErrorHandlingFileSystem.deleteIfExists(
+        workingDirectory,
+        recursive: true,
+      );
+    });
+
     await SwiftPackageManagerUtils.enableSwiftPackageManager(flutterBin, workingDirectoryPath);
     final String appDirectoryPath = await SwiftPackageManagerUtils.createApp(
       flutterBin,
@@ -694,21 +707,22 @@ void main() {
     ],
 ''';
 
-      expect(generatedManifest.contains(expected), isTrue);
+    expect(generatedManifest, contains(expected));
-    } finally {
-      await SwiftPackageManagerUtils.disableSwiftPackageManager(flutterBin, workingDirectoryPath);
-      ErrorHandlingFileSystem.deleteIfExists(
-        workingDirectory,
-        recursive: true,
-      );
-    }
   }, skip: !platform.isMacOS); // [intended] Swift Package Manager only works on macos.
 
   test('Removing the last plugin updates the generated Swift package', () async {
     final Directory workingDirectory = fileSystem.systemTempDirectory
       .createTempSync('swift_package_manager_remove_last_plugin.');
     final String workingDirectoryPath = workingDirectory.path;
-    try {
+
+    addTearDown(() async {
+      await SwiftPackageManagerUtils.disableSwiftPackageManager(flutterBin, workingDirectoryPath);
+      ErrorHandlingFileSystem.deleteIfExists(
+        workingDirectory,
+        recursive: true,
+      );
+    });
+
     await SwiftPackageManagerUtils.enableSwiftPackageManager(
       flutterBin,
       workingDirectoryPath,
@@ -778,22 +792,23 @@ void main() {
     generatedManifest = generatedManifestFile.readAsStringSync();
     const String emptyDependencies = 'dependencies: [\n        \n    ],\n';
 
-      expect(generatedManifest.contains(generatedSwiftDependency), isFalse);
+    expect(generatedManifest, isNot(contains(generatedSwiftDependency)));
-      expect(generatedManifest.contains(emptyDependencies), isTrue);
+    expect(generatedManifest, contains(emptyDependencies));
-    } finally {
-      await SwiftPackageManagerUtils.disableSwiftPackageManager(flutterBin, workingDirectoryPath);
-      ErrorHandlingFileSystem.deleteIfExists(
-        workingDirectory,
-        recursive: true,
-      );
-    }
   }, skip: !platform.isMacOS); // [intended] Swift Package Manager only works on macos.
 
   test('Migrated app builds after Swift Package Manager is turned off', () async {
     final Directory workingDirectory = fileSystem.systemTempDirectory
       .createTempSync('swift_package_manager_turned_off.');
     final String workingDirectoryPath = workingDirectory.path;
-    try {
+
+    addTearDown(() async {
+      await SwiftPackageManagerUtils.disableSwiftPackageManager(flutterBin, workingDirectoryPath);
+      ErrorHandlingFileSystem.deleteIfExists(
+        workingDirectory,
+        recursive: true,
+      );
+    });
+
     await SwiftPackageManagerUtils.enableSwiftPackageManager(
       flutterBin,
       workingDirectoryPath,
@@ -859,8 +874,8 @@ void main() {
     ],
 ''';
 
-      expect(xcodeProject.contains('FlutterGeneratedPluginSwiftPackage'), isTrue);
+    expect(xcodeProject, contains('FlutterGeneratedPluginSwiftPackage'));
-      expect(generatedManifest.contains(generatedSwiftDependency), isTrue);
+    expect(generatedManifest, contains(generatedSwiftDependency));
 
     // Disable Swift Package Manager and do a clean re-build of the app.
     // The build should succeed.
@@ -886,16 +901,9 @@ void main() {
     generatedManifest = generatedManifestFile.readAsStringSync();
     const String emptyDependencies = 'dependencies: [\n        \n    ],\n';
 
-      expect(xcodeProject.contains('FlutterGeneratedPluginSwiftPackage'), isTrue);
+    expect(xcodeProject, contains('FlutterGeneratedPluginSwiftPackage'));
-      expect(generatedManifest.contains('integration_test'), isFalse);
+    expect(generatedManifest, isNot(contains('integration_test')));
-      expect(generatedManifest.contains(emptyDependencies), isTrue);
+    expect(generatedManifest, contains(emptyDependencies));
     expect(cocoaPodsPluginFramework.existsSync(), isTrue);
-    } finally {
-      await SwiftPackageManagerUtils.disableSwiftPackageManager(flutterBin, workingDirectoryPath);
-      ErrorHandlingFileSystem.deleteIfExists(
-        workingDirectory,
-        recursive: true,
-      );
-    }
   }, skip: !platform.isMacOS); // [intended] Swift Package Manager only works on macos.
 }