Refactor ArgParser.usage tests for BuildPlan to reduce duplication. (flutter/engine#56254)

Part of https://github.com/flutter/flutter/issues/157870.

I figured I'd tackle a theme of tests at a time - easier for me to do in little spurts between other tasks.

engine/src/flutter/tools/engine_tool/test/build_plan_test.dart

@@ -891,19 +891,32 @@ void main() {
     );
   });
 
-  test('show builds in help message as long as not a [ci/...] build', () {
+  // These tests should strictly check the usage (--help) output.
-    final testEnv = TestEnvironment.withTestEngine();
+  group('shows instructions based on verbosity', () {
+    /// Creates a configured [ArgParser] based on then environemnt and builds.
+    ///
+    /// By default a non-verbose, non-RBE, Linux x64 configured [BuildPlan]
+    /// is created and used to configure the available options and instructions
+    /// for the returned [ArgParser].
+    ///
+    /// - To use a different [TestEnvironment], provide [environment].
+    /// - To use a different set of builds, provide [builds].
+    ArgParser createArgParser({
+      TestEnvironment? environment,
+      void Function(TestBuilderConfig)? builds,
+    }) {
+      final testEnv = environment ?? TestEnvironment.withTestEngine();
       addTearDown(testEnv.cleanup);
 
       final testConfig = TestBuilderConfig();
-    testConfig.addBuild(
+      if (builds != null) {
-      name: 'ci/host_debug',
+        builds(testConfig);
-      dimension: TestDroneDimension.linux,
+      } else {
-    );
         testConfig.addBuild(
           name: 'linux/host_debug',
           dimension: TestDroneDimension.linux,
         );
+      }
 
       final parser = ArgParser();
       final _ = BuildPlan.configureArgParser(
@@ -917,17 +930,33 @@ void main() {
         help: true,
       );
 
+      return parser;
+    }
+
+    test('show builds in help message as long as not a [ci/...] build', () {
+      final parser = createArgParser(
+        builds: (testConfig) {
+          testConfig.addBuild(
+            name: 'ci/host_debug',
+            dimension: TestDroneDimension.linux,
+          );
+          testConfig.addBuild(
+            name: 'linux/host_debug',
+            dimension: TestDroneDimension.linux,
+          );
+        },
+      );
+
       expect(parser.usage, contains('host_debug'));
       expect(parser.usage, isNot(contains('ci/host_debug')));
     });
 
     test('shows [ci/...] builds if verbose is true', () {
-    final testEnv = TestEnvironment.withTestEngine(
+      final parser = createArgParser(
+        environment: TestEnvironment.withTestEngine(
           verbose: true,
-    );
+        ),
-    addTearDown(testEnv.cleanup);
+        builds: (testConfig) {
-
-    final testConfig = TestBuilderConfig();
           testConfig.addBuild(
             name: 'ci/host_debug',
             dimension: TestDroneDimension.linux,
@@ -936,17 +965,7 @@ void main() {
             name: 'linux/host_debug',
             dimension: TestDroneDimension.linux,
           );
-
-    final parser = ArgParser();
-    final _ = BuildPlan.configureArgParser(
-      parser,
-      testEnv.environment,
-      configs: {
-        'linux_test_config': testConfig.buildConfig(
-          path: 'ci/builders/linux_test_config.json',
-        ),
         },
-      help: true,
       );
 
       expect(parser.usage, contains('host_debug'));
@@ -954,26 +973,7 @@ void main() {
     });
 
     test('hides LTO instructions normally', () {
-    final testEnv = TestEnvironment.withTestEngine();
+      final parser = createArgParser();
-    addTearDown(testEnv.cleanup);
-
-    final testConfig = TestBuilderConfig();
-    testConfig.addBuild(
-      name: 'linux/host_debug',
-      dimension: TestDroneDimension.linux,
-    );
-
-    final parser = ArgParser();
-    final _ = BuildPlan.configureArgParser(
-      parser,
-      testEnv.environment,
-      configs: {
-        'linux_test_config': testConfig.buildConfig(
-          path: 'ci/builders/linux_test_config.json',
-        ),
-      },
-      help: true,
-    );
 
       expect(
         parser.usage,
@@ -982,31 +982,10 @@ void main() {
     });
 
     test('shows LTO instructions if verbose', () {
-    final testEnv = TestEnvironment.withTestEngine(
+      final parser = createArgParser(
+        environment: TestEnvironment.withTestEngine(
           verbose: true,
-    );
-    addTearDown(testEnv.cleanup);
-
-    final testConfig = TestBuilderConfig();
-    testConfig.addBuild(
-      name: 'ci/host_debug',
-      dimension: TestDroneDimension.linux,
-    );
-    testConfig.addBuild(
-      name: 'linux/host_debug',
-      dimension: TestDroneDimension.linux,
-    );
-
-    final parser = ArgParser();
-    final _ = BuildPlan.configureArgParser(
-      parser,
-      testEnv.environment,
-      configs: {
-        'linux_test_config': testConfig.buildConfig(
-          path: 'ci/builders/linux_test_config.json',
         ),
-      },
-      help: true,
       );
 
       expect(
@@ -1016,98 +995,44 @@ void main() {
     });
 
     test('shows RBE instructions if not configured', () {
-    final testEnv = TestEnvironment.withTestEngine(
+      final parser = createArgParser(
+        environment: TestEnvironment.withTestEngine(
           // This is the default, but make it explicit for the test.
           // ignore: avoid_redundant_argument_values
           withRbe: false,
-    );
-    addTearDown(testEnv.cleanup);
-
-    final testConfig = TestBuilderConfig();
-    testConfig.addBuild(
-      name: 'linux/host_debug',
-      dimension: TestDroneDimension.linux,
-    );
-
-    final parser = ArgParser();
-    final _ = BuildPlan.configureArgParser(
-      parser,
-      testEnv.environment,
-      configs: {
-        'linux_test_config': testConfig.buildConfig(
-          path: 'ci/builders/linux_test_config.json',
         ),
-      },
-      help: true,
       );
 
       expect(
         parser.usage,
-      contains('Enable pre-configured remote build execution'),
+        stringContainsInOrder([
-    );
+          'Enable pre-configured remote build execution',
-    expect(
+          'https://flutter.dev/to/engine-rbe',
-      parser.usage,
+        ]),
-      contains('https://flutter.dev/to/engine-rbe'),
       );
     });
 
     test('shows RBE instructions if verbose', () {
-    final testEnv = TestEnvironment.withTestEngine(
+      final parser = createArgParser(
-      withRbe: true,
+        environment: TestEnvironment.withTestEngine(
           verbose: true,
-    );
-    addTearDown(testEnv.cleanup);
-
-    final testConfig = TestBuilderConfig();
-    testConfig.addBuild(
-      name: 'linux/host_debug',
-      dimension: TestDroneDimension.linux,
-    );
-
-    final parser = ArgParser();
-    final _ = BuildPlan.configureArgParser(
-      parser,
-      testEnv.environment,
-      configs: {
-        'linux_test_config': testConfig.buildConfig(
-          path: 'ci/builders/linux_test_config.json',
         ),
-      },
-      help: true,
       );
 
       expect(
         parser.usage,
-      contains('Enable pre-configured remote build execution'),
+        stringContainsInOrder([
-    );
+          'Enable pre-configured remote build execution',
-    expect(
+          'https://flutter.dev/to/engine-rbe',
-      parser.usage,
+        ]),
-      contains('https://flutter.dev/to/engine-rbe'),
       );
     });
 
-  test('hides RBE intsructions if enabled', () {
+    test('hides RBE instructions if enabled', () {
-    final testEnv = TestEnvironment.withTestEngine(
+      final parser = createArgParser(
+        environment: TestEnvironment.withTestEngine(
           withRbe: true,
-    );
-    addTearDown(testEnv.cleanup);
-
-    final testConfig = TestBuilderConfig();
-    testConfig.addBuild(
-      name: 'linux/host_debug',
-      dimension: TestDroneDimension.linux,
-    );
-
-    final parser = ArgParser();
-    final _ = BuildPlan.configureArgParser(
-      parser,
-      testEnv.environment,
-      configs: {
-        'linux_test_config': testConfig.buildConfig(
-          path: 'ci/builders/linux_test_config.json',
         ),
-      },
-      help: true,
       );
 
       expect(
@@ -1121,29 +1046,12 @@ void main() {
     });
 
     test('hides --build-strategy if RBE not enabled', () {
-    final testEnv = TestEnvironment.withTestEngine(
+      final parser = createArgParser(
+        environment: TestEnvironment.withTestEngine(
           // This is the default, but make it explicit for the test.
           // ignore: avoid_redundant_argument_values
           withRbe: false,
-    );
-    addTearDown(testEnv.cleanup);
-
-    final testConfig = TestBuilderConfig();
-    testConfig.addBuild(
-      name: 'linux/host_debug',
-      dimension: TestDroneDimension.linux,
-    );
-
-    final parser = ArgParser();
-    final _ = BuildPlan.configureArgParser(
-      parser,
-      testEnv.environment,
-      configs: {
-        'linux_test_config': testConfig.buildConfig(
-          path: 'ci/builders/linux_test_config.json',
         ),
-      },
-      help: true,
       );
 
       expect(
@@ -1153,27 +1061,10 @@ void main() {
     });
 
     test('shows --build-strategy if RBE enabled', () {
-    final testEnv = TestEnvironment.withTestEngine(
+      final parser = createArgParser(
+        environment: TestEnvironment.withTestEngine(
           withRbe: true,
-    );
-    addTearDown(testEnv.cleanup);
-
-    final testConfig = TestBuilderConfig();
-    testConfig.addBuild(
-      name: 'linux/host_debug',
-      dimension: TestDroneDimension.linux,
-    );
-
-    final parser = ArgParser();
-    final _ = BuildPlan.configureArgParser(
-      parser,
-      testEnv.environment,
-      configs: {
-        'linux_test_config': testConfig.buildConfig(
-          path: 'ci/builders/linux_test_config.json',
         ),
-      },
-      help: true,
       );
 
       expect(
@@ -1183,27 +1074,10 @@ void main() {
     });
 
     test('shows --build-strategy if verbose', () {
-    final testEnv = TestEnvironment.withTestEngine(
+      final parser = createArgParser(
+        environment: TestEnvironment.withTestEngine(
           verbose: true,
-    );
-    addTearDown(testEnv.cleanup);
-
-    final testConfig = TestBuilderConfig();
-    testConfig.addBuild(
-      name: 'linux/host_debug',
-      dimension: TestDroneDimension.linux,
-    );
-
-    final parser = ArgParser();
-    final _ = BuildPlan.configureArgParser(
-      parser,
-      testEnv.environment,
-      configs: {
-        'linux_test_config': testConfig.buildConfig(
-          path: 'ci/builders/linux_test_config.json',
         ),
-      },
-      help: true,
       );
 
       expect(
@@ -1212,28 +1086,20 @@ void main() {
       );
     });
 
+    test('hides --gn-args if not verbose', () {
+      final parser = createArgParser();
+
+      expect(
+        parser.usage,
+        isNot(contains('Additional arguments to provide to "gn"')),
+      );
+    });
+
     test('shows --gn-args if verbose', () {
-    final testEnv = TestEnvironment.withTestEngine(
+      final parser = createArgParser(
+        environment: TestEnvironment.withTestEngine(
           verbose: true,
-    );
-    addTearDown(testEnv.cleanup);
-
-    final testConfig = TestBuilderConfig();
-    testConfig.addBuild(
-      name: 'linux/host_debug',
-      dimension: TestDroneDimension.linux,
-    );
-
-    final parser = ArgParser();
-    final _ = BuildPlan.configureArgParser(
-      parser,
-      testEnv.environment,
-      configs: {
-        'linux_test_config': testConfig.buildConfig(
-          path: 'ci/builders/linux_test_config.json',
         ),
-      },
-      help: true,
       );
 
       expect(
@@ -1241,32 +1107,5 @@ void main() {
         contains('Additional arguments to provide to "gn"'),
       );
     });
-
-  test('hides --gn-args if not verbose', () {
-    final testEnv = TestEnvironment.withTestEngine();
-    addTearDown(testEnv.cleanup);
-
-    final testConfig = TestBuilderConfig();
-    testConfig.addBuild(
-      name: 'linux/host_debug',
-      dimension: TestDroneDimension.linux,
-    );
-
-    final parser = ArgParser();
-    final _ = BuildPlan.configureArgParser(
-      parser,
-      testEnv.environment,
-      configs: {
-        'linux_test_config': testConfig.buildConfig(
-          path: 'ci/builders/linux_test_config.json',
-        ),
-      },
-      help: true,
-    );
-
-    expect(
-      parser.usage,
-      isNot(contains('Additional arguments to provide to "gn"')),
-    );
   });
 }