refactor(transformer): precompile stylesheets

Part of #3605

modules_dart/transform/test/transform/stylesheet_compiler/all_tests.dart

@@ -0,0 +1,96 @@
+library angular2.test.transform.stylesheet_compiler.all_tests;
+
+import 'dart:async';
+import 'dart:convert';
+
+import 'package:angular2/src/transform/stylesheet_compiler/transformer.dart';
+
+import 'package:barback/barback.dart';
+import 'package:guinness/guinness.dart';
+
+const SIMPLE_CSS = '''
+.foo {
+  width: 10px;
+}
+''';
+
+main() {
+  Html5LibDomAdapter.makeCurrent();
+  allTests();
+}
+
+allTests() {
+  StylesheetCompiler subject;
+
+  beforeEach(() {
+    subject = new StylesheetCompiler();
+  });
+
+  it('should accept CSS assets', () {
+    expect(subject.isPrimary(new AssetId('somepackage', 'lib/style.css')))
+        .toBe(true);
+  });
+
+  it('should reject non-CSS assets', () {
+    expect(subject.isPrimary(new AssetId('somepackage', 'lib/style.scss')))
+        .toBe(false);
+  });
+
+  it('should declare outputs', () {
+    var transform = new FakeDeclaringTransform()
+      ..primaryId = new AssetId('somepackage', 'lib/style.css');
+    subject.declareOutputs(transform);
+    expect(transform.outputs.length).toBe(2);
+    expect(transform.outputs[0].toString())
+        .toEqual('somepackage|lib/style.css.dart');
+    expect(transform.outputs[1].toString())
+        .toEqual('somepackage|lib/style.css.shim.dart');
+  });
+
+  it('should compile stylesheets', () async {
+    var cssFile = new Asset.fromString(
+        new AssetId('somepackage', 'lib/style.css'), SIMPLE_CSS);
+    var transform = new FakeTransform()..primaryInput = cssFile;
+    await subject.apply(transform);
+    expect(transform.outputs.length).toBe(2);
+    expect(transform.outputs[0].id.toString())
+        .toEqual('somepackage|lib/style.css.dart');
+    expect(transform.outputs[1].id.toString())
+        .toEqual('somepackage|lib/style.css.shim.dart');
+  });
+}
+
+@proxy
+class FakeTransform implements Transform {
+  final outputs = <Asset>[];
+  Asset primaryInput;
+
+  addOutput(Asset output) {
+    this.outputs.add(output);
+  }
+
+  readInputAsString(AssetId id, {Encoding encoding}) {
+    if (id == primaryInput.id) {
+      return primaryInput.readAsString(encoding: encoding);
+    }
+    throw 'Could not read input $id';
+  }
+
+  noSuchMethod(Invocation i) {
+    throw '${i.memberName} not implemented';
+  }
+}
+
+@proxy
+class FakeDeclaringTransform implements DeclaringTransform {
+  final outputs = <AssetId>[];
+  AssetId primaryId;
+
+  declareOutput(AssetId output) {
+    this.outputs.add(output);
+  }
+
+  noSuchMethod(Invocation i) {
+    throw '${i.memberName} not implemented';
+  }
+}