[flutter_tools] fix performance of tree-shake-icons (#55417)

Fixes the performance issue with tree-shake-icons and filters to ttf mime type. Does not change default or error behavior.

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

@@ -60,9 +60,9 @@ Future<Depfile> copyAssets(Environment environment, Directory outputDirectory) a
         file.parent.createSync(recursive: true);
         final DevFSContent content = entry.value;
         if (content is DevFSFileContent && content.file is File) {
-          inputs.add(globals.fs.file(content.file.path));
+          inputs.add(content.file as File);
           if (!await iconTreeShaker.subsetFont(
-            inputPath: content.file.path,
+            input: content.file as File,
             outputPath: file.path,
             relativePath: entry.key,
           )) {

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

@@ -4,6 +4,7 @@
 
 import 'package:meta/meta.dart';
 import 'package:process/process.dart';
+import 'package:mime/mime.dart' as mime;
 
 import '../../artifacts.dart';
 import '../../base/common.dart';
@@ -66,6 +67,12 @@ class IconTreeShaker {
     }
   }
 
+  /// The MIME type for ttf fonts.
+  static const Set<String> kTtfMimeTypes = <String>{
+    'font/ttf', // based on internet search
+    'application/x-font-ttf', // based on running locally.
+  };
+
   /// The [Source] inputs that targets using this should depend on.
   ///
   /// See [Target.inputs].
@@ -77,6 +84,7 @@ class IconTreeShaker {
 
   final Environment _environment;
   final String _fontManifest;
+  Future<void> _iconDataProcessing;
   Map<String, _IconTreeShakerData> _iconData;
 
   final ProcessManager _processManager;
@@ -89,10 +97,10 @@ class IconTreeShaker {
                    && _environment.defines[kIconTreeShakerFlag] == 'true'
                    && _environment.defines[kBuildMode] != 'debug';
 
-  /// Fills the [_iconData] map.
-  Future<Map<String, _IconTreeShakerData>> _getIconData(Environment environment) async {
+  // Fills the [_iconData] map.
+  Future<void> _getIconData(Environment environment) async {
     if (!enabled) {
-      return null;
+      return;
     }
 
     final File appDill = environment.buildDir.childFile('app.dill');
@@ -119,12 +127,14 @@ class IconTreeShaker {
     );
 
     if (fonts.length != iconData.length) {
-      throwToolExit('Expected to find fonts for ${iconData.keys}, but found '
-                    '${fonts.keys}. This usually means you are refering to '
-                    'font families in an IconData class but not including them '
-                    'in the assets section of your pubspec.yaml, are missing '
-                    'the package that would include them, or are missing '
-                    '"uses-material-design: true".');
+      throwToolExit(
+        'Expected to find fonts for ${iconData.keys}, but found '
+        '${fonts.keys}. This usually means you are refering to '
+        'font families in an IconData class but not including them '
+        'in the assets section of your pubspec.yaml, are missing '
+        'the package that would include them, or are missing '
+        '"uses-material-design: true".',
+      );
     }
 
     final Map<String, _IconTreeShakerData> result = <String, _IconTreeShakerData>{};
@@ -135,13 +145,11 @@ class IconTreeShaker {
         codePoints: iconData[entry.key],
       );
     }
-    return result;
+    _iconData = result;
   }
 
-  /// Calls font-subset, which transforms the `inputPath` font file to a
-  /// subsetted version at `outputPath`.
-  ///
-  /// The `relativePath` parameter
+  /// Calls font-subset, which transforms the [input] font file to a
+  /// subsetted version at [outputPath].
   ///
   /// All parameters are required.
   ///
@@ -150,15 +158,24 @@ class IconTreeShaker {
   /// If the font-subset subprocess fails, it will [throwToolExit].
   /// Otherwise, it will return true.
   Future<bool> subsetFont({
-    @required String inputPath,
+    @required File input,
     @required String outputPath,
     @required String relativePath,
   }) async {
     if (!enabled) {
       return false;
     }
-
-    _iconData ??= await _getIconData(_environment);
+    if (input.lengthSync() < 12) {
+      return false;
+    }
+    final String mimeType = mime.lookupMimeType(
+      input.path,
+      headerBytes: await input.openRead(0, 12).first,
+    );
+    if (!kTtfMimeTypes.contains(mimeType)) {
+      return false;
+    }
+    await (_iconDataProcessing ??= _getIconData(_environment));
     assert(_iconData != null);
 
     final _IconTreeShakerData iconTreeShakerData = _iconData[relativePath];
@@ -176,7 +193,7 @@ class IconTreeShaker {
     final List<String> cmd = <String>[
       fontSubset.path,
       outputPath,
-      inputPath,
+      input.path,
     ];
     final String codePoints = iconTreeShakerData.codePoints.join(' ');
     _logger.printTrace('Running font-subset: ${cmd.join(' ')}, '
@@ -186,9 +203,7 @@ class IconTreeShaker {
       fontSubsetProcess.stdin.writeln(codePoints);
       await fontSubsetProcess.stdin.flush();
       await fontSubsetProcess.stdin.close();
-    } on Exception catch (_) {
-      // handled by checking the exit code.
-    } on OSError catch (_) {  // ignore: dead_code_on_catch_subtype
+    } on Exception {
       // handled by checking the exit code.
     }
 

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

@@ -136,7 +136,7 @@ class BuildBundleCommand extends BuildSubCommand {
       extraGenSnapshotOptions: buildInfo.extraGenSnapshotOptions,
       fileSystemScheme: stringArg('filesystem-scheme'),
       fileSystemRoots: stringsArg('filesystem-root'),
-      treeShakeIcons: boolArg('tree-shake-icons'),
+      treeShakeIcons: buildInfo.treeShakeIcons,
     );
     return FlutterCommandResult.success();
   }

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

@@ -19,7 +19,7 @@ class BuildWebCommand extends BuildSubCommand {
   BuildWebCommand({
     @required bool verboseHelp,
   }) {
-    addTreeShakeIconsFlag();
+    addTreeShakeIconsFlag(enabledByDefault: false);
     usesTargetOption();
     usesPubOption();
     addBuildModeFlags(excludeDebug: true);

packages/flutter_tools/lib/src/runner/flutter_command.dart

@@ -425,10 +425,13 @@ abstract class FlutterCommand extends Command<void> {
     );
   }
 
-  void addTreeShakeIconsFlag() {
+  void addTreeShakeIconsFlag({
+    bool enabledByDefault
+  }) {
     argParser.addFlag('tree-shake-icons',
       negatable: true,
-      defaultsTo: kIconTreeShakerEnabledDefault,
+      defaultsTo: enabledByDefault
+        ?? kIconTreeShakerEnabledDefault,
       help: 'Tree shake icon fonts so that only glyphs used by the application remain.',
     );
   }
@@ -579,8 +582,12 @@ abstract class FlutterCommand extends Command<void> {
         'combination with "--${FlutterOptions.kSplitDebugInfoOption}"',
       );
     }
+    final BuildMode buildMode = getBuildMode();
+    final bool treeShakeIcons = argParser.options.containsKey('tree-shake-icons')
+      && buildMode.isPrecompiled
+      && boolArg('tree-shake-icons');
 
-    return BuildInfo(getBuildMode(),
+    return BuildInfo(buildMode,
       argParser.options.containsKey('flavor')
         ? stringArg('flavor')
         : null,
@@ -601,9 +608,7 @@ abstract class FlutterCommand extends Command<void> {
       buildName: argParser.options.containsKey('build-name')
           ? stringArg('build-name')
           : null,
-      treeShakeIcons: argParser.options.containsKey('tree-shake-icons')
-          ? boolArg('tree-shake-icons')
-          : kIconTreeShakerEnabledDefault,
+      treeShakeIcons: treeShakeIcons,
       splitDebugInfoPath: splitDebugInfoPath,
       dartObfuscation: dartObfuscation,
       dartDefines: argParser.options.containsKey(FlutterOptions.kDartDefinesOption)

packages/flutter_tools/test/general.shard/build_system/targets/icon_tree_shaker_test.dart

@@ -23,38 +23,39 @@ import '../../../src/common.dart';
 import '../../../src/context.dart';
 import '../../../src/mocks.dart' as mocks;
 
-final Platform _kNoAnsiPlatform = FakePlatform(stdoutSupportsAnsi: false);
+final Platform kNoAnsiPlatform = FakePlatform(stdoutSupportsAnsi: false);
+const List<int> _kTtfHeaderBytes = <int>[0, 1, 0, 0, 0, 15, 0, 128, 0, 3, 0, 112];
+
+const String dartPath = '/flutter/dart';
+const String constFinderPath = '/flutter/const_finder.snapshot.dart';
+const String fontSubsetPath = '/flutter/font-subset';
+
+const String inputPath = '/input/fonts/MaterialIcons-Regular.ttf';
+const String outputPath = '/output/fonts/MaterialIcons-Regular.ttf';
+const String relativePath = 'fonts/MaterialIcons-Regular.ttf';
+
+List<String> getConstFinderArgs(String appDillPath) => <String>[
+  dartPath,
+  constFinderPath,
+  '--kernel-file', appDillPath,
+  '--class-library-uri', 'package:flutter/src/widgets/icon_data.dart',
+  '--class-name', 'IconData',
+];
+
+const List<String> fontSubsetArgs = <String>[
+  fontSubsetPath,
+  outputPath,
+  inputPath,
+];
 
 void main() {
   BufferLogger logger;
-  MemoryFileSystem fs;
+  MemoryFileSystem fileSystem;
   MockProcessManager mockProcessManager;
   MockProcess fontSubsetProcess;
   MockArtifacts mockArtifacts;
   DevFSStringContent fontManifestContent;
 
-  const String dartPath = '/flutter/dart';
-  const String constFinderPath = '/flutter/const_finder.snapshot.dart';
-  const String fontSubsetPath = '/flutter/font-subset';
-
-  const String inputPath = '/input/fonts/MaterialIcons-Regular.ttf';
-  const String outputPath = '/output/fonts/MaterialIcons-Regular.ttf';
-  const String relativePath = 'fonts/MaterialIcons-Regular.ttf';
-
-  List<String> getConstFinderArgs(String appDillPath) => <String>[
-    dartPath,
-    constFinderPath,
-    '--kernel-file', appDillPath,
-    '--class-library-uri', 'package:flutter/src/widgets/icon_data.dart',
-    '--class-name', 'IconData',
-  ];
-
-  const List<String> fontSubsetArgs = <String>[
-    fontSubsetPath,
-    outputPath,
-    inputPath,
-  ];
-
   void _addConstFinderInvocation(
     String appDillPath, {
     int exitCode = 0,
@@ -89,19 +90,21 @@ void main() {
     mockProcessManager = MockProcessManager();
     fontSubsetProcess = MockProcess();
     mockArtifacts = MockArtifacts();
-
-    fs = MemoryFileSystem();
+    fileSystem = MemoryFileSystem();
     logger = BufferLogger(
       terminal: AnsiTerminal(
         stdio: mocks.MockStdio(),
-        platform: _kNoAnsiPlatform,
+        platform: kNoAnsiPlatform,
       ),
       outputPreferences: OutputPreferences.test(showColor: false),
     );
 
-    fs.file(constFinderPath).createSync(recursive: true);
-    fs.file(dartPath).createSync(recursive: true);
-    fs.file(fontSubsetPath).createSync(recursive: true);
+    fileSystem.file(constFinderPath).createSync(recursive: true);
+    fileSystem.file(dartPath).createSync(recursive: true);
+    fileSystem.file(fontSubsetPath).createSync(recursive: true);
+    fileSystem.file(inputPath)
+      ..createSync(recursive: true)
+      ..writeAsBytesSync(_kTtfHeaderBytes);
     when(mockArtifacts.getArtifactPath(Artifact.constFinder)).thenReturn(constFinderPath);
     when(mockArtifacts.getArtifactPath(Artifact.fontSubset)).thenReturn(fontSubsetPath);
     when(mockArtifacts.getArtifactPath(Artifact.engineDartBinary)).thenReturn(dartPath);
@@ -109,11 +112,11 @@ void main() {
 
   Environment _createEnvironment(Map<String, String> defines) {
     return Environment.test(
-      fs.directory('/icon_test')..createSync(recursive: true),
+      fileSystem.directory('/icon_test')..createSync(recursive: true),
       defines: defines,
       artifacts: mockArtifacts,
       processManager: FakeProcessManager.any(),
-      fileSystem: fs,
+      fileSystem: fileSystem,
       logger: BufferLogger.test(),
     );
   }
@@ -129,18 +132,19 @@ void main() {
       fontManifestContent,
       logger: logger,
       processManager: mockProcessManager,
-      fileSystem: fs,
+      fileSystem: fileSystem,
       artifacts: mockArtifacts,
     );
 
     expect(
       logger.errorText,
-      'Font subetting is not supported in debug mode. The --tree-shake-icons flag will be ignored.\n',
+      'Font subetting is not supported in debug mode. The --tree-shake-icons'
+      ' flag will be ignored.\n',
     );
     expect(iconTreeShaker.enabled, false);
 
     final bool subsets = await iconTreeShaker.subsetFont(
-      inputPath: inputPath,
+      input: fileSystem.file(inputPath),
       outputPath: outputPath,
       relativePath: relativePath,
     );
@@ -161,7 +165,7 @@ void main() {
       null,
       logger: logger,
       processManager: mockProcessManager,
-      fileSystem: fs,
+      fileSystem: fileSystem,
       artifacts: mockArtifacts,
     );
 
@@ -185,7 +189,7 @@ void main() {
       fontManifestContent,
       logger: logger,
       processManager: mockProcessManager,
-      fileSystem: fs,
+      fileSystem: fileSystem,
       artifacts: mockArtifacts,
     );
 
@@ -209,13 +213,13 @@ void main() {
       fontManifestContent,
       logger: logger,
       processManager: mockProcessManager,
-      fileSystem: fs,
+      fileSystem: fileSystem,
       artifacts: mockArtifacts,
     );
 
     expect(
-      () => iconTreeShaker.subsetFont(
-        inputPath: inputPath,
+      () async => await iconTreeShaker.subsetFont(
+        input: fileSystem.file(inputPath),
         outputPath: outputPath,
         relativePath: relativePath,
       ),
@@ -223,20 +227,20 @@ void main() {
     );
   });
 
-  testWithoutContext('The happy path', () async {
+  testWithoutContext('Can subset a font', () async {
     final Environment environment = _createEnvironment(<String, String>{
       kIconTreeShakerFlag: 'true',
       kBuildMode: 'release',
     });
-    final File appDill = environment.buildDir.childFile('app.dill')..createSync(recursive: true);
-    fs.file(inputPath).createSync(recursive: true);
+    final File appDill = environment.buildDir.childFile('app.dill')
+      ..createSync(recursive: true);
 
     final IconTreeShaker iconTreeShaker = IconTreeShaker(
       environment,
       fontManifestContent,
       logger: logger,
       processManager: mockProcessManager,
-      fileSystem: fs,
+      fileSystem: fileSystem,
       artifacts: mockArtifacts,
     );
 
@@ -245,7 +249,7 @@ void main() {
     _resetFontSubsetInvocation(stdinSink: stdinSink);
 
     bool subsetted = await iconTreeShaker.subsetFont(
-      inputPath: inputPath,
+      input: fileSystem.file(inputPath),
       outputPath: outputPath,
       relativePath: relativePath,
     );
@@ -254,7 +258,7 @@ void main() {
 
     expect(subsetted, true);
     subsetted = await iconTreeShaker.subsetFont(
-      inputPath: inputPath,
+      input: fileSystem.file(inputPath),
       outputPath: outputPath,
       relativePath: relativePath,
     );
@@ -265,33 +269,104 @@ void main() {
     verify(mockProcessManager.start(fontSubsetArgs)).called(2);
   });
 
+  testWithoutContext('Does not subset a non-ttf font', () async {
+    final Environment environment = _createEnvironment(<String, String>{
+      kIconTreeShakerFlag: 'true',
+      kBuildMode: 'release',
+    });
+    final File appDill = environment.buildDir.childFile('app.dill')
+      ..createSync(recursive: true);
+
+    final IconTreeShaker iconTreeShaker = IconTreeShaker(
+      environment,
+      fontManifestContent,
+      logger: logger,
+      processManager: mockProcessManager,
+      fileSystem: fileSystem,
+      artifacts: mockArtifacts,
+    );
+
+    final mocks.CompleterIOSink stdinSink = mocks.CompleterIOSink();
+    _addConstFinderInvocation(appDill.path, stdout: validConstFinderResult);
+    _resetFontSubsetInvocation(stdinSink: stdinSink);
+
+    final File notAFont = fileSystem.file('input/foo/bar.txt')
+      ..createSync(recursive: true)
+      ..writeAsStringSync('I could not think of a better string');
+    final bool subsetted = await iconTreeShaker.subsetFont(
+      input: notAFont,
+      outputPath: outputPath,
+      relativePath: relativePath,
+    );
+    expect(subsetted, false);
+
+    verifyNever(mockProcessManager.run(getConstFinderArgs(appDill.path)));
+    verifyNever(mockProcessManager.start(fontSubsetArgs));
+  });
+
+  testWithoutContext('Does not subset an invalid ttf font', () async {
+    final Environment environment = _createEnvironment(<String, String>{
+      kIconTreeShakerFlag: 'true',
+      kBuildMode: 'release',
+    });
+    final File appDill = environment.buildDir.childFile('app.dill')
+      ..createSync(recursive: true);
+
+    final IconTreeShaker iconTreeShaker = IconTreeShaker(
+      environment,
+      fontManifestContent,
+      logger: logger,
+      processManager: mockProcessManager,
+      fileSystem: fileSystem,
+      artifacts: mockArtifacts,
+    );
+
+    final mocks.CompleterIOSink stdinSink = mocks.CompleterIOSink();
+    _addConstFinderInvocation(appDill.path, stdout: validConstFinderResult);
+    _resetFontSubsetInvocation(stdinSink: stdinSink);
+
+    final File notAFont = fileSystem.file(inputPath)
+      ..writeAsBytesSync(<int>[0, 1, 2]);
+    final bool subsetted = await iconTreeShaker.subsetFont(
+      input: notAFont,
+      outputPath: outputPath,
+      relativePath: relativePath,
+    );
+
+    expect(subsetted, false);
+    verifyNever(mockProcessManager.run(getConstFinderArgs(appDill.path)));
+    verifyNever(mockProcessManager.start(fontSubsetArgs));
+  });
+
   testWithoutContext('Non-constant instances', () async {
     final Environment environment = _createEnvironment(<String, String>{
       kIconTreeShakerFlag: 'true',
       kBuildMode: 'release',
     });
-    final File appDill = environment.buildDir.childFile('app.dill')..createSync(recursive: true);
-    fs.file(inputPath).createSync(recursive: true);
+    final File appDill = environment.buildDir.childFile('app.dill')
+      ..createSync(recursive: true);
 
     final IconTreeShaker iconTreeShaker = IconTreeShaker(
       environment,
       fontManifestContent,
       logger: logger,
       processManager: mockProcessManager,
-      fileSystem: fs,
+      fileSystem: fileSystem,
       artifacts: mockArtifacts,
     );
 
     _addConstFinderInvocation(appDill.path, stdout: constFinderResultWithInvalid);
 
-    expect(
-      iconTreeShaker.subsetFont(
-        inputPath: inputPath,
+    await expectLater(
+      () async => await iconTreeShaker.subsetFont(
+        input: fileSystem.file(inputPath),
         outputPath: outputPath,
         relativePath: relativePath,
       ),
       throwsToolExit(
-        message: 'Avoid non-constant invocations of IconData or try to build again with --no-tree-shake-icons.',
+        message:
+          'Avoid non-constant invocations of IconData or try to build'
+          ' again with --no-tree-shake-icons.',
       ),
     );
 
@@ -304,15 +379,16 @@ void main() {
       kIconTreeShakerFlag: 'true',
       kBuildMode: 'release',
     });
-    final File appDill = environment.buildDir.childFile('app.dill')..createSync(recursive: true);
-    fs.file(inputPath).createSync(recursive: true);
+    final File appDill = environment.buildDir.childFile('app.dill')
+      ..createSync(recursive: true);
+    fileSystem.file(inputPath).createSync(recursive: true);
 
     final IconTreeShaker iconTreeShaker = IconTreeShaker(
       environment,
       fontManifestContent,
       logger: logger,
       processManager: mockProcessManager,
-      fileSystem: fs,
+      fileSystem: fileSystem,
       artifacts: mockArtifacts,
     );
 
@@ -320,9 +396,9 @@ void main() {
     _addConstFinderInvocation(appDill.path, stdout: validConstFinderResult);
     _resetFontSubsetInvocation(exitCode: -1, stdinSink: stdinSink);
 
-    expect(
-      iconTreeShaker.subsetFont(
-        inputPath: inputPath,
+    await expectLater(
+      () async => await iconTreeShaker.subsetFont(
+        input: fileSystem.file(inputPath),
         outputPath: outputPath,
         relativePath: relativePath,
       ),
@@ -330,7 +406,7 @@ void main() {
     );
 
     verify(mockProcessManager.run(getConstFinderArgs(appDill.path))).called(1);
-    verifyNever(mockProcessManager.start(fontSubsetArgs));
+    verify(mockProcessManager.start(fontSubsetArgs)).called(1);
   });
 
   testWithoutContext('font-subset throws on write to sdtin', () async {
@@ -338,15 +414,15 @@ void main() {
       kIconTreeShakerFlag: 'true',
       kBuildMode: 'release',
     });
-    final File appDill = environment.buildDir.childFile('app.dill')..createSync(recursive: true);
-    fs.file(inputPath).createSync(recursive: true);
+    final File appDill = environment.buildDir.childFile('app.dill')
+      ..createSync(recursive: true);
 
     final IconTreeShaker iconTreeShaker = IconTreeShaker(
       environment,
       fontManifestContent,
       logger: logger,
       processManager: mockProcessManager,
-      fileSystem: fs,
+      fileSystem: fileSystem,
       artifacts: mockArtifacts,
     );
 
@@ -354,9 +430,9 @@ void main() {
     _addConstFinderInvocation(appDill.path, stdout: validConstFinderResult);
     _resetFontSubsetInvocation(exitCode: -1, stdinSink: stdinSink);
 
-    expect(
-      iconTreeShaker.subsetFont(
-        inputPath: inputPath,
+    await expectLater(
+      () async => await iconTreeShaker.subsetFont(
+        input: fileSystem.file(inputPath),
         outputPath: outputPath,
         relativePath: relativePath,
       ),
@@ -364,7 +440,7 @@ void main() {
     );
 
     verify(mockProcessManager.run(getConstFinderArgs(appDill.path))).called(1);
-    verifyNever(mockProcessManager.start(fontSubsetArgs));
+    verify(mockProcessManager.start(fontSubsetArgs)).called(1);
   });
 
   testWithoutContext('Invalid font manifest', () async {
@@ -372,8 +448,8 @@ void main() {
       kIconTreeShakerFlag: 'true',
       kBuildMode: 'release',
     });
-    final File appDill = environment.buildDir.childFile('app.dill')..createSync(recursive: true);
-    fs.file(inputPath).createSync(recursive: true);
+    final File appDill = environment.buildDir.childFile('app.dill')
+      ..createSync(recursive: true);
 
     fontManifestContent = DevFSStringContent(invalidFontManifestJson);
 
@@ -382,15 +458,15 @@ void main() {
       fontManifestContent,
       logger: logger,
       processManager: mockProcessManager,
-      fileSystem: fs,
+      fileSystem: fileSystem,
       artifacts: mockArtifacts,
     );
 
     _addConstFinderInvocation(appDill.path, stdout: validConstFinderResult);
 
-    expect(
-      iconTreeShaker.subsetFont(
-        inputPath: inputPath,
+    await expectLater(
+      () async => await iconTreeShaker.subsetFont(
+        input: fileSystem.file(inputPath),
         outputPath: outputPath,
         relativePath: relativePath,
       ),
@@ -406,8 +482,8 @@ void main() {
       kIconTreeShakerFlag: 'true',
       kBuildMode: 'release',
     });
-    final File appDill = environment.buildDir.childFile('app.dill')..createSync(recursive: true);
-    fs.file(inputPath).createSync(recursive: true);
+    final File appDill = environment.buildDir.childFile('app.dill')
+      ..createSync(recursive: true);
 
     fontManifestContent = DevFSStringContent(invalidFontManifestJson);
 
@@ -416,15 +492,15 @@ void main() {
       fontManifestContent,
       logger: logger,
       processManager: mockProcessManager,
-      fileSystem: fs,
+      fileSystem: fileSystem,
       artifacts: mockArtifacts,
     );
 
     _addConstFinderInvocation(appDill.path, exitCode: -1);
 
-    expect(
-      iconTreeShaker.subsetFont(
-        inputPath: inputPath,
+    await expectLater(
+      () async => await iconTreeShaker.subsetFont(
+        input: fileSystem.file(inputPath),
         outputPath: outputPath,
         relativePath: relativePath,
       ),