Add BaseTransform.consumePrimary to barback.

pkg/barback/test/package_graph/group_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.package_graph.group_test;
 
 import 'dart:async';
 
 import 'package:barback/barback.dart';
 import 'package:scheduled_test/scheduled_test.dart';
@@ skipping 173 matching lines @@
         ])]
       ]});
       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();
     });
 
-    // TODO(nweiz): re-enable this test when a transformer can consume its
-    // primary input (issue 16612).
-    // 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();
-    // });
+    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")..consumePrimary = true]
+        ]), new TransformerGroup([
+          [new RewriteTransformer("x", "b")],
+          [new RewriteTransformer("b", "z")..consumePrimary = true]
+        ])]
+      ]});
+      updateSources(["app|foo.a", "app|foo.x"]);
+      expectAsset("app|foo.a");
+      expectAsset("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")]
         ])]
       ]});
@@ skipping 71 matching lines @@
           [new RewriteTransformer("b", "c")]
         ]),
         new RewriteTransformer("x", "x")
       ]]});
       updateSources(["app|foo.x"]);
       expectNoAsset("app|foo.c");
       expectAsset("app|foo.x", "foo.x");
       buildShouldSucceed();
     });
 
+    test("doesn't pass through an input that's consumed by a group but not "
+        "by transformers", () {
+      initGraph(["app|foo.a"], {"app": [[
+        new TransformerGroup([
+          [new RewriteTransformer("a", "b")..consumePrimary = true],
+        ]),
+        new RewriteTransformer("x", "y")
+      ]]});
+      updateSources(["app|foo.a"]);
+      expectNoAsset("app|foo.a");
+      expectAsset("app|foo.b", "foo.b");
+      buildShouldSucceed();
+    });
+
+    test("doesn't pass through an input that's consumed 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")..consumePrimary = true
+      ]]});
+      updateSources(["app|foo.x"]);
+      expectNoAsset("app|foo.x");
+      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"]);
@@ skipping 102 matching lines @@
       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")]);
   });
 }