Add support for transformer clusters to barback.

pkg/barback/test/package_graph/group_test.dart

Index: pkg/barback/test/package_graph/group_test.dart
diff --git a/pkg/barback/test/package_graph/group_test.dart b/pkg/barback/test/package_graph/group_test.dart
new file mode 100644
index 0000000000000000000000000000000000000000..c81b3b6997c56a935bf2a3980267e6eee5621090
--- /dev/null
+++ b/pkg/barback/test/package_graph/group_test.dart
@@ -0,0 +1,401 @@
+// 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.package_graph.group_test;
+
+import 'package:barback/barback.dart';
+import 'package:scheduled_test/scheduled_test.dart';
+
+import '../utils.dart';
+
+main() {
+  initConfig();
+  test("runs transforms in a group", () {
+    initGraph(["app|foo.a"], {"app": [
+      [new TransformerGroup([
+        [new RewriteTransformer("a", "b")],
+        [new RewriteTransformer("b", "c")]
+      ])]
+    ]});
+    updateSources(["app|foo.a"]);
+    expectNoAsset("app|foo.b");
+    expectAsset("app|foo.c", "foo.b.c");
+    buildShouldSucceed();
+  });
+
+  test("passes the output of a group to the next phase", () {
+    initGraph(["app|foo.a"], {"app": [
+      [new TransformerGroup([
+        [new RewriteTransformer("a", "b")],
+        [new RewriteTransformer("b", "c")]
+      ])],
+      [new RewriteTransformer("c", "d")]
+    ]});
+    updateSources(["app|foo.a"]);
+    expectNoAsset("app|foo.c");
+    expectAsset("app|foo.d", "foo.b.c.d");
+    buildShouldSucceed();
+  });
+
+  test("passes the output of a previous phase to a group", () {
+    initGraph(["app|foo.a"], {"app": [
+      [new RewriteTransformer("a", "b")],
+      [new TransformerGroup([
+        [new RewriteTransformer("b", "c")],
+        [new RewriteTransformer("c", "d")]
+      ])]
+    ]});
+    updateSources(["app|foo.a"]);
+    expectNoAsset("app|foo.b");
+    expectAsset("app|foo.d", "foo.b.c.d");
+    buildShouldSucceed();
+  });
+
+  test("intermediate assets in a group are usable as secondary inputs within "
+      "that group", () {
+    initGraph({
+      "app|foo.a": "contents",
+      "app|bar.txt": "foo.inc"
+    }, {"app": [
+      [new TransformerGroup([
+        [new RewriteTransformer("a", "inc")],
+        [new ManyToOneTransformer("txt")]
+      ])]
+    ]});
+
+    updateSources(["app|foo.a", "app|bar.txt"]);
+    expectAsset("app|bar.out", "contents.inc");
+    buildShouldSucceed();
+  });
+
+  test("groups can be nested", () {
+    initGraph(["app|foo.a", "app|bar.x"], {"app": [
+      [new TransformerGroup([
+        [new TransformerGroup([
+          [new RewriteTransformer("a", "b")],
+          [new RewriteTransformer("b", "c")]
+        ]), new TransformerGroup([
+          [new RewriteTransformer("x", "y"), new RewriteTransformer("a", "y")],
+          [new RewriteTransformer("y", "z")]
+        ])],
+        [new RewriteTransformer("c", "d")]
+      ])]
+    ]});
+    updateSources(["app|foo.a", "app|bar.x"]);
+    expectAsset("app|foo.d", "foo.b.c.d");
+    expectAsset("app|foo.z", "foo.y.z");
+    expectAsset("app|bar.z", "bar.y.z");
+    buildShouldSucceed();
+  });
+
+  test("an updated asset is propagated through a group", () {
+    initGraph(["app|foo.a"], {"app": [
+      [new TransformerGroup([
+        [new RewriteTransformer("a", "b")],
+        [new RewriteTransformer("b", "c")]
+      ])]
+    ]});
+
+    updateSources(["app|foo.a"]);
+    expectNoAsset("app|foo.b");
+    expectAsset("app|foo.c", "foo.b.c");
+    buildShouldSucceed();
+
+    modifyAsset("app|foo.a", "new foo");
+    updateSources(["app|foo.a"]);
+    expectAsset("app|foo.c", "new foo.b.c");
+    buildShouldSucceed();
+  });
+
+  test("an updated asset only runs the necessary transforms in a group", () {
+    var rewriteA = new RewriteTransformer("a", "b");
+    var rewriteX = new RewriteTransformer("x", "b");
+    initGraph(["app|foo.a", "app|bar.x"], {"app": [
+      [new TransformerGroup([
+        [rewriteA, rewriteX],
+        [new RewriteTransformer("b", "c")]
+      ])]
+    ]});
+
+    updateSources(["app|foo.a", "app|bar.x"]);
+    expectNoAsset("app|foo.b");
+    expectAsset("app|foo.c", "foo.b.c");
+    expectAsset("app|bar.c", "bar.b.c");
+    buildShouldSucceed();
+
+    modifyAsset("app|foo.a", "new foo");
+    updateSources(["app|foo.a"]);
+    expectAsset("app|foo.c", "new foo.b.c");
+    buildShouldSucceed();
+
+    expect(rewriteA.numRuns, completion(equals(2)));
+    expect(rewriteX.numRuns, completion(equals(1)));
+  });
+
+  group("encapsulation", () {
+    test("a group can't see a parallel transform's outputs", () {
+      initGraph(["app|foo.x"], {"app": [[
+        new TransformerGroup([
+          [new RewriteTransformer("a", "b")],
+          [new RewriteTransformer("b", "c")]
+        ]),
+        new RewriteTransformer("x", "b")
+      ]]});
+      updateSources(["app|foo.x"]);
+      expectAsset("app|foo.b", "foo.b");
+      expectNoAsset("app|foo.c");
+      buildShouldSucceed();
+    });
+
+    test("a parallel transform can't see a group's outputs", () {
+      initGraph(["app|foo.a"], {"app": [[
+        new TransformerGroup([
+          [new RewriteTransformer("a", "b")],
+          [new RewriteTransformer("b", "c")]
+        ]),
+        new RewriteTransformer("c", "z")
+      ]]});
+      updateSources(["app|foo.a"]);
+      expectAsset("app|foo.c", "foo.b.c");
+      expectNoAsset("app|foo.z");
+      buildShouldSucceed();
+    });
+
+    test("a parallel transform can't see a group's intermediate assets", () {
+      initGraph(["app|foo.a"], {"app": [[
+        new TransformerGroup([
+          [new RewriteTransformer("a", "b")],
+          [new RewriteTransformer("b", "c")]
+        ]),
+        new RewriteTransformer("b", "z")
+      ]]});
+      updateSources(["app|foo.a"]);
+      expectAsset("app|foo.c", "foo.b.c");
+      expectNoAsset("app|foo.z");
+      buildShouldSucceed();
+    });
+
+    test("parallel groups can't see one another's intermediate assets", () {
+      initGraph(["app|foo.a", "app|bar.x"], {"app": [
+        [new TransformerGroup([
+          [new RewriteTransformer("a", "b")],
+          [new RewriteTransformer("b", "c")]
+        ]), new TransformerGroup([
+          [new RewriteTransformer("x", "b")],
+          [new RewriteTransformer("b", "z")]
+        ])]
+      ]});
+      updateSources(["app|foo.a", "app|bar.x"]);
+      expectAsset("app|foo.c", "foo.b.c");
+      expectAsset("app|bar.z", "bar.b.z");
+      expectNoAsset("app|foo.z");
+      expectNoAsset("app|bar.c");
+      buildShouldSucceed();
+    });
+
+    test("parallel groups' intermediate assets can't collide", () {
+      initGraph(["app|foo.a", "app|foo.x"], {"app": [
+        [new TransformerGroup([
+          [new RewriteTransformer("a", "b")],
+          [new RewriteTransformer("b", "c")]
+        ]), new TransformerGroup([
+          [new RewriteTransformer("x", "b")],
+          [new RewriteTransformer("b", "z")]
+        ])]
+      ]});
+      updateSources(["app|foo.a", "app|foo.x"]);
+      expectAsset("app|foo.c", "foo.b.c");
+      expectAsset("app|foo.z", "foo.b.z");
+      buildShouldSucceed();
+    });
+  });
+
+  group("pass-through", () {
+    test("passes an unused input through a group", () {
+      initGraph(["app|foo.x"], {"app": [
+        [new TransformerGroup([
+          [new RewriteTransformer("a", "b")],
+          [new RewriteTransformer("b", "c")]
+        ])]
+      ]});
+      updateSources(["app|foo.x"]);
+      expectNoAsset("app|foo.c");
+      expectAsset("app|foo.x", "foo");
+      buildShouldSucceed();
+    });
+
+    test("passes an unused input through parallel groups", () {
+      initGraph(["app|foo.x"], {"app": [
+        [new TransformerGroup([
+          [new RewriteTransformer("a", "b")],
+          [new RewriteTransformer("b", "c")]
+        ]), new TransformerGroup([
+          [new RewriteTransformer("1", "2")],
+          [new RewriteTransformer("2", "3")]
+        ])]
+      ]});
+      updateSources(["app|foo.x"]);
+      expectNoAsset("app|foo.c");
+      expectNoAsset("app|foo.3");
+      expectAsset("app|foo.x", "foo");
+      buildShouldSucceed();
+    });
+
+    test("passes an unused input through a group and a transform", () {
+      initGraph(["app|foo.x"], {"app": [[
+        new TransformerGroup([
+          [new RewriteTransformer("a", "b")],
+          [new RewriteTransformer("b", "c")]
+        ]),
+        new RewriteTransformer("1", "2")
+      ]]});
+      updateSources(["app|foo.x"]);
+      expectNoAsset("app|foo.c");
+      expectNoAsset("app|foo.2");
+      expectAsset("app|foo.x", "foo");
+      buildShouldSucceed();
+    });
+
+    test("doesn't pass through an input that's used by a group but not by "
+        "transformers", () {
+      initGraph(["app|foo.a"], {"app": [[
+        new TransformerGroup([
+          [new RewriteTransformer("a", "b")],
+          [new RewriteTransformer("b", "c")]
+        ]),
+        new RewriteTransformer("x", "y")
+      ]]});
+      updateSources(["app|foo.a"]);
+      expectNoAsset("app|foo.a");
+      expectNoAsset("app|foo.y");
+      expectAsset("app|foo.c", "foo.b.c");
+      buildShouldSucceed();
+    });
+
+    test("doesn't pass through an input that's used by transformers but not by "
+        "a group", () {
+      initGraph(["app|foo.x"], {"app": [[
+        new TransformerGroup([
+          [new RewriteTransformer("a", "b")],
+          [new RewriteTransformer("b", "c")]
+        ]),
+        new RewriteTransformer("x", "y")
+      ]]});
+      updateSources(["app|foo.x"]);
+      expectNoAsset("app|foo.x");
+      expectNoAsset("app|foo.c");
+      expectAsset("app|foo.y", "foo.y");
+      buildShouldSucceed();
+    });
+
+    test("doesn't detect a collision for an input that's modified in-place by "
+        "a transformer", () {
+      initGraph(["app|foo.x"], {"app": [[
+        new TransformerGroup([
+          [new RewriteTransformer("a", "b")],
+          [new RewriteTransformer("b", "c")]
+        ]),
+        new RewriteTransformer("x", "x")
+      ]]});
+      updateSources(["app|foo.x"]);
+      expectAsset("app|foo.x", "foo.x");
+      buildShouldSucceed();
+    });
+
+    test("doesn't detect a collision for an input that's modified in-place by "
+        "a group", () {
+      initGraph(["app|foo.a"], {"app": [[
+        new TransformerGroup([[new RewriteTransformer("a", "a")]]),
+        new RewriteTransformer("x", "y")
+      ]]});
+      updateSources(["app|foo.a"]);
+      expectAsset("app|foo.a", "foo.a");
+      buildShouldSucceed();
+    });
+  });
+
+  test("runs transforms in an added group", () {
+    var rewrite = new RewriteTransformer("a", "z");
+    initGraph(["app|foo.a"], {"app": [[rewrite]]});
+
+    updateSources(["app|foo.a"]);
+    expectAsset("app|foo.z", "foo.z");
+    buildShouldSucceed();
+
+    updateTransformers("app", [[
+      rewrite,
+      new TransformerGroup([
+        [new RewriteTransformer("a", "b")],
+        [new RewriteTransformer("b", "c")]
+      ])
+    ]]);
+    expectAsset("app|foo.z", "foo.z");
+    expectAsset("app|foo.c", "foo.b.c");
+    buildShouldSucceed();
+  });
+
+  test("doesn't re-run transforms in a re-added group", () {
+    var rewrite1 = new RewriteTransformer("a", "b");
+    var rewrite2 = new RewriteTransformer("b", "c");
+    var group = new TransformerGroup([[rewrite1], [rewrite2]]);
+    initGraph(["app|foo.a"], {"app": [[group]]});
+
+    updateSources(["app|foo.a"]);
+    expectAsset("app|foo.c", "foo.b.c");
+    buildShouldSucceed();
+
+    updateTransformers("app", [
+      [group, new RewriteTransformer("a", "z")]
+    ]);
+    expectAsset("app|foo.c", "foo.b.c");
+    expectAsset("app|foo.z", "foo.z");
+    buildShouldSucceed();
+
+    expect(rewrite1.numRuns, completion(equals(1)));
+    expect(rewrite2.numRuns, completion(equals(1)));
+  });
+
+  test("doesn't pass through an input that's used by an added group", () {
+    var rewrite = new RewriteTransformer("x", "z");
+    initGraph(["app|foo.a"], {"app": [[rewrite]]});
+
+    updateSources(["app|foo.a"]);
+    expectAsset("app|foo.a", "foo");
+    buildShouldSucceed();
+
+    updateTransformers("app", [
+      [rewrite, new TransformerGroup([
+        [new RewriteTransformer("a", "b")],
+        [new RewriteTransformer("b", "c")]
+      ])]
+    ]);
+    expectNoAsset("app|foo.a");
+    expectAsset("app|foo.c", "foo.b.c");
+    buildShouldSucceed();
+  });
+
+  // TODO(nweiz): make the collision error message nice
+  test("reports collisions within a group", () {
+    initGraph(["app|foo.a", "app|foo.x"], {"app": [
+      [new TransformerGroup([
+        [new RewriteTransformer("a", "b")],
+        [new RewriteTransformer("x", "b")]
+      ])]
+    ]});
+    updateSources(["app|foo.a", "app|foo.x"]);
+    buildShouldFail([isAssetCollisionException("app|foo.b")]);
+  });
+
+  test("reports collisions between a group and a non-grouped transform", () {
+    initGraph(["app|foo.a", "app|foo.x"], {"app": [[
+      new TransformerGroup([
+        [new RewriteTransformer("a", "b")],
+        [new RewriteTransformer("b", "c")]
+      ]),
+      new RewriteTransformer("x", "c")
+    ]]});
+    updateSources(["app|foo.a", "app|foo.x"]);
+    buildShouldFail([isAssetCollisionException("app|foo.c")]);
+  });
+}