Move barback to a more event-based model.

pkg/barback/test/package_graph/transform_test.dart

Index: pkg/barback/test/package_graph/transform_test.dart
diff --git a/pkg/barback/test/package_graph/transform_test.dart b/pkg/barback/test/package_graph/transform_test.dart
index d62d460516ca5d7b17f7122655a800a9237da4da..26132587c8c396f37ecb7fee8bfcd5f81ae2d763 100644
--- a/pkg/barback/test/package_graph/transform_test.dart
+++ b/pkg/barback/test/package_graph/transform_test.dart
@@ -129,6 +129,18 @@ main() {
     buildShouldSucceed();
   });
 
+  test("outputs are inaccessible once used", () {
+    initGraph(["app|foo.a"], {"app": [
+      [new RewriteTransformer("a", "b")],
+      [new RewriteTransformer("a", "c")]
+    ]});
+    updateSources(["app|foo.a"]);
+    expectAsset("app|foo.b", "foo.b");
+    expectNoAsset("app|foo.a");
+    expectNoAsset("app|foo.c");
+    buildShouldSucceed();
+  });
+
   test("does not reapply transform when inputs are not modified", () {
     var transformer = new RewriteTransformer("blub", "blab");
     initGraph(["app|foo.blub"], {"app": [[transformer]]});
@@ -268,6 +280,23 @@ main() {
     buildShouldSucceed();
   });
 
+  test("discards outputs from a transform whose primary input is removed "
+      "during processing", () {
+    var rewrite = new RewriteTransformer("txt", "out");
+    initGraph(["app|foo.txt"], {"app": [[rewrite]]});
+
+    rewrite.pauseApply();
+    updateSources(["app|foo.txt"]);
+    schedule(() => rewrite.started);
+    schedule(() {
+      removeSources(["app|foo.txt"]);
+      rewrite.resumeApply();
+    });
+
+    expectNoAsset("app|foo.out");
+    buildShouldSucceed();
+  });
+
   test("reapplies a transform when a non-primary input changes", () {
     initGraph({
       "app|a.txt": "a.inc",
@@ -285,6 +314,69 @@ main() {
     buildShouldSucceed();
   });
 
+  test("applies a transform when it becomes newly primary", () {
+    initGraph({
+      "app|foo.txt": "this",
+    }, {"app": [[new CheckContentTransformer("that", " and the other")]]});
+
+    updateSources(["app|foo.txt"]);
+    expectAsset("app|foo.txt", "this");
+    buildShouldSucceed();
+
+    modifyAsset("app|foo.txt", "that");
+    schedule(() => updateSources(["app|foo.txt"]));
+
+    expectAsset("app|foo.txt", "that and the other");
+    buildShouldSucceed();
+  });
+
+  test("applies the correct transform if an asset is modified during isPrimary",
+      () {
+    var check1 = new CheckContentTransformer("first", "#1");
+    var check2 = new CheckContentTransformer("second", "#2");
+    initGraph({
+      "app|foo.txt": "first",
+    }, {"app": [[check1, check2]]});
+
+    check1.pauseIsPrimary("app|foo.txt");
+    updateSources(["app|foo.txt"]);
+    // Ensure that we're waiting on check1's isPrimary.
+    schedule(pumpEventQueue);
+
+    modifyAsset("app|foo.txt", "second");
+    schedule(() {
+      updateSources(["app|foo.txt"]);
+      check1.resumeIsPrimary("app|foo.txt");
+    });
+
+    expectAsset("app|foo.txt", "second#2");
+    buildShouldSucceed();
+  });
+
+  test("applies the correct transform if an asset is removed and added during "
+      "isPrimary", () {
+    var check1 = new CheckContentTransformer("first", "#1");
+    var check2 = new CheckContentTransformer("second", "#2");
+    initGraph({
+      "app|foo.txt": "first",
+    }, {"app": [[check1, check2]]});
+
+    check1.pauseIsPrimary("app|foo.txt");
+    updateSources(["app|foo.txt"]);
+    // Ensure that we're waiting on check1's isPrimary.
+    schedule(pumpEventQueue);
+
+    schedule(() => removeSources(["app|foo.txt"]));
+    modifyAsset("app|foo.txt", "second");
+    schedule(() {
+      updateSources(["app|foo.txt"]);
+      check1.resumeIsPrimary("app|foo.txt");
+    });
+
+    expectAsset("app|foo.txt", "second#2");
+    buildShouldSucceed();
+  });
+
   test("restarts processing if a change occurs during processing", () {
     var transformer = new RewriteTransformer("txt", "out");
     initGraph(["app|foo.txt"], {"app": [[transformer]]});
@@ -312,6 +404,34 @@ main() {
     });
   });
 
+  test("aborts processing if the primary input is removed during processing",
+      () {
+    var transformer = new RewriteTransformer("txt", "out");
+    initGraph(["app|foo.txt"], {"app": [[transformer]]});
+
+    transformer.pauseApply();
+
+    schedule(() {
+      updateSources(["app|foo.txt"]);
+
+      // Wait for the transform to start.
+      return transformer.started;
+    });
+
+    schedule(() {
+      // Now remove its primary input while it's running.
+      removeSources(["app|foo.txt"]);
+      transformer.resumeApply();
+    });
+
+    expectNoAsset("app|foo.out");
+    buildShouldSucceed();
+
+    schedule(() {
+      expect(transformer.numRuns, equals(1));
+    });
+  });
+
   test("handles an output moving from one transformer to another", () {
     // In the first run, "shared.out" is created by the "a.a" transformer.
     initGraph({
@@ -400,6 +520,281 @@ main() {
     buildShouldSucceed();
   });
 
+  test("doesn't return an asset until it's finished rebuilding", () {
+    initGraph(["app|foo.in"], {"app": [
+      [new RewriteTransformer("in", "mid")],
+      [new RewriteTransformer("mid", "out")]
+    ]});
+
+    updateSources(["app|foo.in"]);
+    expectAsset("app|foo.out", "foo.mid.out");
+    buildShouldSucceed();
+
+    pauseProvider();
+    modifyAsset("app|foo.in", "new");
+    schedule(() => updateSources(["app|foo.in"]));
+    expectAssetDoesNotComplete("app|foo.out");
+    buildShouldNotBeDone();
+
+    resumeProvider();
+    expectAsset("app|foo.out", "new.mid.out");
+    buildShouldSucceed();
+  });
+
+  test("doesn't return an asset until its in-place transform is done", () {
+    var rewrite = new RewriteTransformer("txt", "txt");
+    initGraph(["app|foo.txt"], {"app": [[rewrite]]});
+
+    rewrite.pauseApply();
+    updateSources(["app|foo.txt"]);
+    expectAssetDoesNotComplete("app|foo.txt");
+
+    schedule(rewrite.resumeApply);
+    expectAsset("app|foo.txt", "foo.txt");
+    buildShouldSucceed();
+  });
+
+  test("doesn't return an asset until we know it won't be transformed",
+      () {
+    var rewrite = new RewriteTransformer("txt", "txt");
+    initGraph(["app|foo.a"], {"app": [[rewrite]]});
+
+    rewrite.pauseIsPrimary("app|foo.a");
+    updateSources(["app|foo.a"]);
+    expectAssetDoesNotComplete("app|foo.a");
+
+    schedule(() => rewrite.resumeIsPrimary("app|foo.a"));
+    expectAsset("app|foo.a", "foo");
+    buildShouldSucceed();
+  });
+
+  test("doesn't return a modified asset until we know it will still be "
+      "transformed", () {
+    var rewrite = new RewriteTransformer("txt", "txt");
+    initGraph(["app|foo.txt"], {"app": [[rewrite]]});
+
+    updateSources(["app|foo.txt"]);
+    expectAsset("app|foo.txt", "foo.txt");
+    buildShouldSucceed();
+
+    schedule(() => rewrite.pauseIsPrimary("app|foo.txt"));
+    schedule(() => updateSources(["app|foo.txt"]));
+    expectAssetDoesNotComplete("app|foo.txt");
+
+    schedule(() => rewrite.resumeIsPrimary("app|foo.txt"));
+    expectAsset("app|foo.txt", "foo.txt");
+    buildShouldSucceed();
+  });
+
+  test("doesn't return an asset that's removed during isPrimary", () {
+    var rewrite = new RewriteTransformer("txt", "txt");
+    initGraph(["app|foo.txt"], {"app": [[rewrite]]});
+
+    rewrite.pauseIsPrimary("app|foo.txt");
+    updateSources(["app|foo.txt"]);
+    // Make sure we're waiting on isPrimary.
+    schedule(pumpEventQueue);
+
+    schedule(() {
+      removeSources(["app|foo.txt"]);
+      rewrite.resumeIsPrimary("app|foo.txt");
+    });
+    expectNoAsset("app|foo.txt");
+    buildShouldSucceed();
+  });
+
+  test("doesn't transform an asset that goes from primary to non-primary "
+      "during isPrimary", () {
+    var check = new CheckContentTransformer("do", "ne");
+    initGraph({
+      "app|foo.txt": "do"
+    }, {"app": [[check]]});
+
+    check.pauseIsPrimary("app|foo.txt");
+    updateSources(["app|foo.txt"]);
+    // Make sure we're waiting on isPrimary.
+    schedule(pumpEventQueue);
+
+    modifyAsset("app|foo.txt", "don't");
+    schedule(() {
+      updateSources(["app|foo.txt"]);
+      check.resumeIsPrimary("app|foo.txt");
+    });
+
+    expectAsset("app|foo.txt", "don't");
+    buildShouldSucceed();
+  });
+
+  test("transforms an asset that goes from non-primary to primary "
+      "during isPrimary", () {
+    var check = new CheckContentTransformer("do", "ne");
+    initGraph({
+      "app|foo.txt": "don't"
+    }, {"app": [[check]]});
+
+    check.pauseIsPrimary("app|foo.txt");
+    updateSources(["app|foo.txt"]);
+    // Make sure we're waiting on isPrimary.
+    schedule(pumpEventQueue);
+
+    modifyAsset("app|foo.txt", "do");
+    schedule(() {
+      updateSources(["app|foo.txt"]);
+      check.resumeIsPrimary("app|foo.txt");
+    });
+
+    expectAsset("app|foo.txt", "done");
+    buildShouldSucceed();
+  });
+
+  test("doesn't return an asset that's removed during another transformer's "
+      "isPrimary", () {
+    var rewrite1 = new RewriteTransformer("txt", "txt");
+    var rewrite2 = new RewriteTransformer("md", "md");
+    initGraph(["app|foo.txt", "app|foo.md"], {"app": [[rewrite1, rewrite2]]});
+
+    rewrite2.pauseIsPrimary("app|foo.md");
+    updateSources(["app|foo.txt", "app|foo.md"]);
+    // Make sure we're waiting on the correct isPrimary.
+    schedule(pumpEventQueue);
+
+    schedule(() {
+      removeSources(["app|foo.txt"]);
+      rewrite2.resumeIsPrimary("app|foo.md");
+    });
+    expectNoAsset("app|foo.txt");
+    expectAsset("app|foo.md", "foo.md");
+    buildShouldSucceed();
+  });
+
+  test("doesn't transform an asset that goes from primary to non-primary "
+      "during another transformer's isPrimary", () {
+    var rewrite = new RewriteTransformer("md", "md");
+    var check = new CheckContentTransformer("do", "ne");
+    initGraph({
+      "app|foo.txt": "do",
+      "app|foo.md": "foo"
+    }, {"app": [[rewrite, check]]});
+
+    rewrite.pauseIsPrimary("app|foo.md");
+    updateSources(["app|foo.txt", "app|foo.md"]);
+    // Make sure we're waiting on the correct isPrimary.
+    schedule(pumpEventQueue);
+
+    modifyAsset("app|foo.txt", "don't");
+    schedule(() {
+      updateSources(["app|foo.txt"]);
+      rewrite.resumeIsPrimary("app|foo.md");
+    });
+
+    expectAsset("app|foo.txt", "don't");
+    expectAsset("app|foo.md", "foo.md");
+    buildShouldSucceed();
+  });
+
+  test("transforms an asset that goes from non-primary to primary "
+      "during another transformer's isPrimary", () {
+    var rewrite = new RewriteTransformer("md", "md");
+    var check = new CheckContentTransformer("do", "ne");
+    initGraph({
+      "app|foo.txt": "don't",
+      "app|foo.md": "foo"
+    }, {"app": [[rewrite, check]]});
+
+    rewrite.pauseIsPrimary("app|foo.md");
+    updateSources(["app|foo.txt", "app|foo.md"]);
+    // Make sure we're waiting on the correct isPrimary.
+    schedule(pumpEventQueue);
+
+    modifyAsset("app|foo.txt", "do");
+    schedule(() {
+      updateSources(["app|foo.txt"]);
+      rewrite.resumeIsPrimary("app|foo.md");
+    });
+
+    expectAsset("app|foo.txt", "done");
+    expectAsset("app|foo.md", "foo.md");
+    buildShouldSucceed();
+  });
+
+  test("removes pipelined transforms when the root primary input is removed",
+      () {
+    initGraph(["app|foo.txt"], {"app": [
+      [new RewriteTransformer("txt", "mid")],
+      [new RewriteTransformer("mid", "out")]
+    ]});
+
+    updateSources(["app|foo.txt"]);
+    expectAsset("app|foo.out", "foo.mid.out");
+    buildShouldSucceed();
+
+    schedule(() => removeSources(["app|foo.txt"]));
+    expectNoAsset("app|foo.out");
+    buildShouldSucceed();
+  });
+
+  test("removes pipelined transforms when the parent ceases to generate the "
+      "primary input", () {
+    initGraph({"app|foo.txt": "foo.mid"}, {'app': [
+      [new OneToManyTransformer('txt')],
+      [new RewriteTransformer('mid', 'out')]
+    ]});
+
+    updateSources(['app|foo.txt']);
+    expectAsset('app|foo.out', 'spread txt.out');
+    buildShouldSucceed();
+
+    modifyAsset("app|foo.txt", "bar.mid");
+    schedule(() => updateSources(["app|foo.txt"]));
+    expectNoAsset('app|foo.out');
+    expectAsset('app|bar.out', 'spread txt.out');
+    buildShouldSucceed();
+  });
+
+  test("returns an asset even if an unrelated build is running", () {
+    initGraph([
+      "app|foo.in",
+      "app|bar.in",
+    ], {"app": [[new RewriteTransformer("in", "out")]]});
+
+    updateSources(["app|foo.in", "app|bar.in"]);
+    expectAsset("app|foo.out", "foo.out");
+    expectAsset("app|bar.out", "bar.out");
+    buildShouldSucceed();
+
+    pauseProvider();
+    modifyAsset("app|foo.in", "new");
+    schedule(() => updateSources(["app|foo.in"]));
+    expectAssetDoesNotComplete("app|foo.out");
+    expectAsset("app|bar.out", "bar.out");
+    buildShouldNotBeDone();
+
+    resumeProvider();
+    expectAsset("app|foo.out", "new.out");
+    buildShouldSucceed();
+  });
+
+  test("doesn't report AssetNotFound until all builds are finished", () {
+    initGraph([
+      "app|foo.in",
+    ], {"app": [[new RewriteTransformer("in", "out")]]});
+
+    updateSources(["app|foo.in"]);
+    expectAsset("app|foo.out", "foo.out");
+    buildShouldSucceed();
+
+    pauseProvider();
+    schedule(() => updateSources(["app|foo.in"]));
+    expectAssetDoesNotComplete("app|foo.out");
+    expectAssetDoesNotComplete("app|non-existent.out");
+    buildShouldNotBeDone();
+
+    resumeProvider();
+    expectAsset("app|foo.out", "foo.out");
+    expectNoAsset("app|non-existent.out");
+    buildShouldSucceed();
+  });
+
   test("doesn't emit a result until all builds are finished", () {
     var rewrite = new RewriteTransformer("txt", "out");
     initGraph([