First pass at build dependency graph for barback.

pkg/barback/test/asset_graph/source_test.dart

+// Copyright (c) 2013, the Dart project authors.  Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+library barback.test.asset_graph.source_test;
+
+import 'dart:async';
+
+import 'package:barback/barback.dart';
+import 'package:barback/src/asset_graph.dart';
+import 'package:scheduled_test/scheduled_test.dart';
+
+import '../utils.dart';
+
+main() {
+  initConfig();
+  test("gets a source asset", () {
+    var provider = new MockProvider(["app|foo.txt"]);
+    var graph = new AssetGraph(provider, []);
+    graph.updateSources([new AssetId.parse("app|foo.txt")]);
+
+    expectAsset(graph, "app|foo.txt");
+  });
+
+  test("doesn't get an unknown source", () {
+    var provider = new MockProvider(["app|foo.txt"]);
+    var graph = new AssetGraph(provider, []);
+
+    expectNoAsset(graph, "app|unknown.txt");
+  });
+
+  test("doesn't get an asset that isn't an updated source", () {
+    var provider = new MockProvider(["app|foo.txt"]);
+    var graph = new AssetGraph(provider, []);
+
+    expectNoAsset(graph, "app|foo.txt");
+  });
+
+  test("gets a source asset if not transformed", () {
+    var provider = new MockProvider(["app|foo.txt"]);
+    var graph = new AssetGraph(provider, [
+      [new RewriteTransformer("nottxt", "whatever")]
+    ]);
+    graph.updateSources([new AssetId.parse("app|foo.txt")]);
+
+    expectAsset(graph, "app|foo.txt");
+  });
+
+  test("doesn't get a removed source", () {
+    var provider = new MockProvider(["app|foo.txt"]);
+    var graph = new AssetGraph(provider, [[]]);
+    graph.updateSources([new AssetId.parse("app|foo.txt")]);
+
+    expectAsset(graph, "app|foo.txt");
+
+    schedule(() {
+      graph.removeSources([new AssetId.parse("app|foo.txt")]);
+    });
+
+    expectNoAsset(graph, "app|foo.txt");
+  });
+
+  test("collapses redundant updates", () {
+    var provider = new MockProvider({"app|foo.blub": "foo"});
+    var transformer = new RewriteTransformer("blub", "blab");
+    var graph = new AssetGraph(provider, [[transformer]]);
+
+    schedule(() {
+      // Make a bunch of synchronous update calls.
+      graph.updateSources([new AssetId.parse("app|foo.blub")]);
+      graph.updateSources([new AssetId.parse("app|foo.blub")]);
+      graph.updateSources([new AssetId.parse("app|foo.blub")]);
+      graph.updateSources([new AssetId.parse("app|foo.blub")]);
+    });
+
+    expectAsset(graph, "app|foo.blab", "foo.blab");
+
+    schedule(() {
+      expect(transformer.numRuns, equals(1));
+    });
+  });
+
+  test("a removal cancels out an update", () {
+    var provider = new MockProvider(["app|foo.txt"]);
+    var graph = new AssetGraph(provider, [[]]);
+
+    schedule(() {
+      graph.updateSources([new AssetId.parse("app|foo.txt")]);
+      graph.removeSources([new AssetId.parse("app|foo.txt")]);
+    });
+
+    expectNoAsset(graph, "app|foo.txt");
+  });
+
+  test("an update cancels out a removal", () {
+    var provider = new MockProvider(["app|foo.txt"]);
+    var graph = new AssetGraph(provider, [[]]);
+
+    schedule(() {
+      graph.removeSources([new AssetId.parse("app|foo.txt")]);
+      graph.updateSources([new AssetId.parse("app|foo.txt")]);
+    });
+
+    expectAsset(graph, "app|foo.txt");
+  });
+}