[flutter_tools] allow passing non-config inputs (#54228)

packages/flutter_tools/lib/src/build_system/build_system.dart

@@ -295,6 +295,7 @@ class Environment {
     @required ProcessManager processManager,
     Directory buildDir,
     Map<String, String> defines = const <String, String>{},
+    Map<String, String> inputs = const <String, String>{},
   }) {
     // Compute a unique hash of this build's particular environment.
     // Sort the keys by key so that the result is stable. We always
@@ -325,6 +326,7 @@ class Environment {
       logger: logger,
       artifacts: artifacts,
       processManager: processManager,
+      inputs: inputs,
     );
   }
 
@@ -338,6 +340,7 @@ class Environment {
     Directory flutterRootDir,
     Directory buildDir,
     Map<String, String> defines = const <String, String>{},
+    Map<String, String> inputs = const <String, String>{},
     @required FileSystem fileSystem,
     @required Logger logger,
     @required Artifacts artifacts,
@@ -350,6 +353,7 @@ class Environment {
       flutterRootDir: flutterRootDir ?? testDirectory,
       buildDir: buildDir,
       defines: defines,
+      inputs: inputs,
       fileSystem: fileSystem,
       logger: logger,
       artifacts: artifacts,
@@ -369,6 +373,7 @@ class Environment {
     @required this.logger,
     @required this.fileSystem,
     @required this.artifacts,
+    @required this.inputs,
   });
 
   /// The [Source] value which is substituted with the path to [projectDir].
@@ -420,6 +425,16 @@ class Environment {
   /// which prevents the config from leaking into different builds.
   final Map<String, String> defines;
 
+  /// Additional input files passed to the build targets.
+  ///
+  /// Unlike [defines], values set here do not force a new build configuration.
+  /// This is useful for passing file inputs that may have changing paths
+  /// without running builds from scratch.
+  ///
+  /// It is the responsibility of the [Target] to declare that an input was
+  /// used in an output depfile.
+  final Map<String, String> inputs;
+
   /// The root build directory shared by all builds.
   final Directory rootBuildDir;
 

packages/flutter_tools/lib/src/commands/assemble.dart

@@ -64,6 +64,13 @@ class AssembleCommand extends FlutterCommand {
       abbr: 'd',
       help: 'Allows passing configuration to a target with --define=target=key=value.',
     );
+    argParser.addMultiOption(
+      'input',
+      abbr: 'i',
+      help: 'Allows passing additional inputs with --input=key=value. Unlike '
+      'defines, additional inputs do not generate a new configuration, instead '
+      'they are treated as dependencies of the targets that use them.'
+    );
     argParser.addOption('depfile', help: 'A file path where a depfile will be written. '
       'This contains all build inputs and outputs in a make style syntax'
     );
@@ -99,7 +106,7 @@ class AssembleCommand extends FlutterCommand {
       return const <CustomDimensions, String>{};
     }
     try {
-      final Environment localEnvironment = environment;
+      final Environment localEnvironment = createEnvironment();
       return <CustomDimensions, String>{
         CustomDimensions.commandBuildBundleTargetPlatform: localEnvironment.defines['TargetPlatform'],
         CustomDimensions.commandBuildBundleIsModule: '${futterProject.isModule}',
@@ -111,7 +118,7 @@ class AssembleCommand extends FlutterCommand {
   }
 
   /// The target(s) we are building.
-  List<Target> get targets {
+  List<Target> createTargets() {
     if (argResults.rest.isEmpty) {
       throwToolExit('missing target name for flutter assemble.');
     }
@@ -132,7 +139,7 @@ class AssembleCommand extends FlutterCommand {
   }
 
   /// The environmental configuration for a build invocation.
-  Environment get environment {
+  Environment createEnvironment() {
     final FlutterProject flutterProject = FlutterProject.current();
     String output = stringArg('output');
     if (output == null) {
@@ -149,6 +156,7 @@ class AssembleCommand extends FlutterCommand {
           .childDirectory('flutter_build'),
       projectDir: flutterProject.directory,
       defines: _parseDefines(stringsArg('define')),
+      inputs: _parseDefines(stringsArg('input')),
       cacheDir: globals.cache.getRoot(),
       flutterRootDir: globals.fs.directory(Cache.flutterRoot),
       artifacts: globals.artifacts,
@@ -179,13 +187,17 @@ class AssembleCommand extends FlutterCommand {
 
   @override
   Future<FlutterCommandResult> runCommand() async {
-    final List<Target> targets = this.targets;
+    final List<Target> targets = createTargets();
     final Target target = targets.length == 1 ? targets.single : _CompositeTarget(targets);
-    final BuildResult result = await globals.buildSystem.build(target, environment, buildSystemConfig: BuildSystemConfig(
+    final BuildResult result = await globals.buildSystem.build(
+      target,
+      createEnvironment(),
+      buildSystemConfig: BuildSystemConfig(
         resourcePoolSize: argResults.wasParsed('resource-pool-size')
           ? int.tryParse(stringArg('resource-pool-size'))
           : null,
-    ));
+        ),
+      );
     if (!result.success) {
       for (final ExceptionMeasurement measurement in result.exceptions.values) {
         globals.printError('Target ${measurement.target} failed: ${measurement.exception}',

packages/flutter_tools/test/commands.shard/hermetic/assemble_test.dart

@@ -23,7 +23,7 @@ void main() {
     Cache: () => FakeCache(),
   });
 
-  testbed.test('Can run a build', () async {
+  testbed.test('flutter assemble can run a build', () async {
     when(globals.buildSystem.build(any, any, buildSystemConfig: anyNamed('buildSystemConfig')))
       .thenAnswer((Invocation invocation) async {
         return BuildResult(success: true);
@@ -34,7 +34,7 @@ void main() {
     expect(testLogger.traceText, contains('build succeeded.'));
   });
 
-  testbed.test('Can parse defines whose values contain =', () async {
+  testbed.test('flutter assemble can parse defines whose values contain =', () async {
     when(globals.buildSystem.build(any, any, buildSystemConfig: anyNamed('buildSystemConfig')))
       .thenAnswer((Invocation invocation) async {
         expect((invocation.positionalArguments[1] as Environment).defines, containsPair('FooBar', 'fizz=2'));
@@ -46,7 +46,19 @@ void main() {
     expect(testLogger.traceText, contains('build succeeded.'));
   });
 
-  testbed.test('Throws ToolExit if not provided with output', () async {
+  testbed.test('flutter assemble can parse inputs', () async {
+    when(globals.buildSystem.build(any, any, buildSystemConfig: anyNamed('buildSystemConfig')))
+      .thenAnswer((Invocation invocation) async {
+        expect((invocation.positionalArguments[1] as Environment).inputs, containsPair('Foo', 'Bar.txt'));
+        return BuildResult(success: true);
+      });
+    final CommandRunner<void> commandRunner = createTestCommandRunner(AssembleCommand());
+    await commandRunner.run(<String>['assemble', '-o Output', '-iFoo=Bar.txt', 'debug_macos_bundle_flutter_assets']);
+
+    expect(testLogger.traceText, contains('build succeeded.'));
+  });
+
+  testbed.test('flutter assemble throws ToolExit if not provided with output', () async {
     when(globals.buildSystem.build(any, any, buildSystemConfig: anyNamed('buildSystemConfig')))
       .thenAnswer((Invocation invocation) async {
         return BuildResult(success: true);
@@ -57,7 +69,7 @@ void main() {
       throwsToolExit());
   });
 
-  testbed.test('Throws ToolExit if called with non-existent rule', () async {
+  testbed.test('flutter assemble throws ToolExit if called with non-existent rule', () async {
     when(globals.buildSystem.build(any, any, buildSystemConfig: anyNamed('buildSystemConfig')))
       .thenAnswer((Invocation invocation) async {
         return BuildResult(success: true);
@@ -68,7 +80,7 @@ void main() {
       throwsToolExit());
   });
 
-  testbed.test('Does not log stack traces during build failure', () async {
+  testbed.test('flutter assemble does not log stack traces during build failure', () async {
     final StackTrace testStackTrace = StackTrace.current;
     when(globals.buildSystem.build(any, any, buildSystemConfig: anyNamed('buildSystemConfig')))
       .thenAnswer((Invocation invocation) async {
@@ -84,7 +96,7 @@ void main() {
     expect(testLogger.errorText, isNot(contains(testStackTrace.toString())));
   });
 
-  testbed.test('Only writes input and output files when the values change', () async {
+  testbed.test('flutter assemble only writes input and output files when the values change', () async {
     when(globals.buildSystem.build(any, any, buildSystemConfig: anyNamed('buildSystemConfig')))
       .thenAnswer((Invocation invocation) async {
         return BuildResult(

packages/flutter_tools/test/general.shard/build_system/build_system_test.dart

@@ -375,6 +375,31 @@ void main() {
     expect(environmentA.buildDir.path, isNot(environmentB.buildDir.path));
   });
 
+  testWithoutContext('Additional inputs do not change the build configuration',  () async {
+    final Environment environmentA = Environment.test(
+      fileSystem.currentDirectory,
+      artifacts: MockArtifacts(),
+      processManager: FakeProcessManager.any(),
+      fileSystem: fileSystem,
+      logger: BufferLogger.test(),
+      inputs: <String, String>{
+        'C': 'D',
+      }
+    );
+    final Environment environmentB = Environment.test(
+      fileSystem.currentDirectory,
+      artifacts: MockArtifacts(),
+      processManager: FakeProcessManager.any(),
+      fileSystem: fileSystem,
+      logger: BufferLogger.test(),
+      inputs: <String, String>{
+        'A': 'B',
+      }
+    );
+
+    expect(environmentA.buildDir.path, equals(environmentB.buildDir.path));
+  });
+
   testWithoutContext('A target with depfile dependencies can delete stale outputs on the first run',  () async {
     final BuildSystem buildSystem = setUpBuildSystem(fileSystem);
     int called = 0;