check that public API of dart:ui conforms to web implementation (#8256)

ci/build.sh

@@ -12,3 +12,9 @@ ninja -C out/host_debug_unopt generate_dart_ui
 # Analyze the dart UI
 flutter/ci/analyze.sh
 flutter/ci/licenses.sh
+
+# Check that dart libraries conform
+cd flutter/web_sdk
+pub get
+cd ..
+dart web_sdk/test/api_conform_test.dart

web_sdk/pubspec.yaml

@@ -0,0 +1,6 @@
+name: web_sdk_tests
+author: Flutter Authors <flutter-dev@googlegroups.com>
+
+dev_dependencies:
+  analyzer: any
+  test: any

web_sdk/test/api_conform_test.dart

@@ -0,0 +1,134 @@
+// Copyright 2013 The Flutter Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+import 'package:analyzer/analyzer.dart';
+
+int main() {
+  // These files just contain imports to the part files;
+  final CompilationUnit uiUnit = parseDartFile('lib/ui/ui.dart',
+      parseFunctionBodies: false, suppressErrors: false);
+  final CompilationUnit webUnit = parseDartFile('lib/stub_ui/ui.dart',
+      parseFunctionBodies: false, suppressErrors: false);
+  final Map<String, ClassDeclaration> uiClasses = <String, ClassDeclaration>{};
+  final Map<String, ClassDeclaration> webClasses = <String, ClassDeclaration>{};
+
+  // Gather all public classes from each library. For now we are skiping
+  // other top level members.
+  _collectPublicClasses(uiUnit, uiClasses, 'lib/ui/');
+  _collectPublicClasses(webUnit, webClasses, 'lib/stub_ui/');
+
+  if (uiClasses.isEmpty || webClasses.isEmpty) {
+    print('Warning: did not resolve any classes.');
+  }
+
+  bool failed = false;
+  print('Checking ${uiClasses.length} public classes.');
+  for (String className in uiClasses.keys) {
+    final ClassDeclaration uiClass = uiClasses[className];
+    final ClassDeclaration webClass = webClasses[className];
+    // If the web class is missing there isn't much left to do here. Print a
+    // warning and move along.
+    if (webClass == null) {
+      failed = true;
+      print('Warning: lib/ui/ui.dart contained public class $className, but '
+          'this was missing from lib/stub_ui/ui.dart.');
+      continue;
+    }
+    // Next will check that the public methods exposed in each library are
+    // identical.
+    final Map<String, MethodDeclaration> uiMethods = <String, MethodDeclaration>{};
+    final Map<String, MethodDeclaration> webMethods = <String, MethodDeclaration>{};
+    _collectPublicMethods(uiClass, uiMethods);
+    _collectPublicMethods(webClass, webMethods);
+
+    for (String methodName in uiMethods.keys) {
+      final MethodDeclaration uiMethod = uiMethods[methodName];
+      final MethodDeclaration webMethod = webMethods[methodName];
+      if (webMethod == null) {
+        failed = true;
+        print(
+          'Warning: lib/ui/ui.dart $className.$methodName is missing from lib/stub_ui/ui.dart.',
+        );
+        continue;
+      }
+      if (uiMethod.parameters == null || webMethod.parameters == null) {
+        continue;
+      }
+      if (uiMethod.parameters.parameters.length != webMethod.parameters.parameters.length) {
+        failed = true;
+        print(
+            'Warning: lib/ui/ui.dart $className.$methodName has a different parameter '
+            'length than in lib/stub_ui/ui.dart.');
+      }
+      // Technically you could re-order named parameters and still be valid,
+      // but we enforce that they are identical.
+      for (int i = 0; i < uiMethod.parameters.parameters.length && i < webMethod.parameters.parameters.length; i++) {
+        final FormalParameter uiParam = uiMethod.parameters.parameters[i];
+        final FormalParameter webParam = webMethod.parameters.parameters[i];
+        if (webParam.identifier.name != uiParam.identifier.name) {
+          failed = true;
+          print('Warning: lib/ui/ui.dart $className.$methodName parameter $i'
+              ' ${uiParam.identifier.name} has a different name in lib/stub_ui/ui.dart.');
+        }
+        if (uiParam.isPositional && !webParam.isPositional) {
+          failed = true;
+          print('Warning: lib/ui/ui.dart $className.$methodName parameter $i'
+              '${uiParam.identifier.name} is positional, but not in lib/stub_ui/ui.dart.');
+        }
+        if (uiParam.isNamed && !webParam.isNamed) {
+          failed = true;
+          print('Warning: lib/ui/ui.dart $className.$methodName parameter $i'
+              '${uiParam.identifier.name} is named, but not in lib/stub_ui/ui.dart.');
+        }
+      }
+    }
+  }
+  if (failed) {
+    print('Failure!');
+    return 1;
+  }
+  print('Success!');
+  return 0;
+}
+
+// Collects all public classes defined by the part files of [unit].
+void _collectPublicClasses(CompilationUnit unit,
+    Map<String, ClassDeclaration> destination, String root) {
+  for (Directive directive in unit.directives) {
+    if (directive is! PartDirective) {
+      continue;
+    }
+    final PartDirective partDirective = directive;
+    final String literalUri = partDirective.uri.toString();
+    final CompilationUnit subUnit = parseDartFile(
+      '$root${literalUri.substring(1, literalUri.length - 1)}',
+      parseFunctionBodies: false,
+      suppressErrors: false,
+    );
+    for (CompilationUnitMember member in subUnit.declarations) {
+      if (member is! ClassDeclaration) {
+        continue;
+      }
+      final ClassDeclaration classDeclaration = member;
+      if (classDeclaration.name.name.startsWith('_')) {
+        continue;
+      }
+      destination[classDeclaration.name.name] = classDeclaration;
+    }
+  }
+}
+
+void _collectPublicMethods(ClassDeclaration classDeclaration,
+    Map<String, MethodDeclaration> destination) {
+  for (ClassMember member in classDeclaration.members) {
+    if (member is! MethodDeclaration) {
+      continue;
+    }
+    final MethodDeclaration method = member;
+    if (method.name.name.startsWith('_')) {
+      continue;
+    }
+    destination[method.name.name] = method;
+  }
+}