Don't return outputs from a removed PhaseInput.

Also clean up a few things in Phase.

R=alanknight@google.com

Review URL: https://codereview.chromium.org//37813002

git-svn-id: https://dart.googlecode.com/svn/branches/bleeding_edge/dart@29127 260f80e4-7a28-3924-810f-c04153c831b5

pkg/barback/lib/src/phase.dart

@@ -281,13 +281,11 @@ class Phase {
       if (!input.isDirty) return new Future.value(new Set());
       return input.process().then(_handleOutputs);
     }));
-    outputFutures.addAll(_groups.values.map((input) {
-      if (!input.isDirty) return new Future.value(new Set());
-      return input.process().then(_handleOutputs);
+    outputFutures.addAll(_groups.values.map((group) {
+      if (!group.isDirty) return new Future.value(new Set());
+      return group.process().then(_handleOutputs);
     }));
 
-    // TODO(nweiz): handle pass-through.
-
     return Future.wait(outputFutures).then((_) {
       // Report collisions in a deterministic order.
       outputIds = outputIds.toList();

pkg/barback/lib/src/phase_input.dart

@@ -273,9 +273,15 @@ class PhaseInput {
   }
 
   /// Processes the transforms for this input.
+  ///
+  /// Returns the set of newly-created asset nodes that transforms have emitted
+  /// for this input. The assets returned this way are guaranteed not to be
+  /// [AssetState.REMOVED].
   Future<Set<AssetNode>> process() {
-    if (_adjustTransformersFuture == null) return _processTransforms();
-    return _waitForTransformers(() => _processTransforms());
+    return _waitForTransformers(() => _processTransforms()).then((outputs) {
+      if (input.state.isRemoved) return new Set();
+      return outputs;
+    });
   }
 
   /// Runs [callback] once all the transformers are adjusted correctly and the

pkg/barback/test/package_graph/transform_test.dart

@@ -806,6 +806,30 @@ main() {
     buildShouldSucceed();
   });
 
+  test("one transformer takes a long time while the other finishes, then "
+      "the input is removed", () {
+    var rewrite1 = new RewriteTransformer("txt", "out1");
+    var rewrite2 = new RewriteTransformer("txt", "out2");
+    initGraph(["app|foo.txt"], {"app": [[rewrite1, rewrite2]]});
+
+    rewrite1.pauseApply();
+
+    updateSources(["app|foo.txt"]);
+
+    // Wait for rewrite1 to pause and rewrite2 to finish.
+    schedule(pumpEventQueue);
+
+    removeSources(["app|foo.txt"]);
+
+    // Make sure the removal is processed completely before we restart rewrite2.
+    schedule(pumpEventQueue);
+    rewrite1.resumeApply();
+
+    buildShouldSucceed();
+    expectNoAsset("app|foo.out1");
+    expectNoAsset("app|foo.out2");
+  });
+
   group("pass-through", () {
     test("passes an asset through a phase in which no transforms apply", () {
       initGraph([