Add BaseTransform.consumePrimary to barback.

pkg/barback/test/package_graph/transform/pass_through_test.dart

Index: pkg/barback/test/package_graph/transform/pass_through_test.dart
diff --git a/pkg/barback/test/package_graph/transform/pass_through_test.dart b/pkg/barback/test/package_graph/transform/pass_through_test.dart
index eb90418385fd1d0b89e218f5253f261f46f2840a..c8b1d7ecc139c905df267bd3c368731a134b1caa 100644
--- a/pkg/barback/test/package_graph/transform/pass_through_test.dart
+++ b/pkg/barback/test/package_graph/transform/pass_through_test.dart
@@ -270,4 +270,148 @@ main() {
     expectAsset("app|foo.txt", "foo.txt");
     buildShouldSucceed();
   });
+

[Bob Nystrom, 2014/03/07 21:54:11]

Might be worth making a separate suite for these.

[nweiz, 2014/03/11 21:44:05]

Done.

+  group("consumeInput", () {
+    test("a transform consumes its input without overwriting it", () {
+      initGraph([
+        "app|foo.txt"
+      ], {
+        "app": [[new RewriteTransformer("txt", "out")..consumePrimary = true]]
+      });
+
+      updateSources(["app|foo.txt"]);
+      expectAsset("app|foo.out", "foo.out");
+      expectNoAsset("app|foo.txt");
+      buildShouldSucceed();
+    });
+
+    test("a transform consumes its input while a sibling overwrites it", () {
+      initGraph([
+        "app|foo.txt"
+      ], {
+        "app": [[
+          new RewriteTransformer("txt", "out")..consumePrimary = true,
+          new RewriteTransformer("txt", "txt")
+        ]]
+      });
+
+      updateSources(["app|foo.txt"]);
+      expectAsset("app|foo.out", "foo.out");
+      expectAsset("app|foo.txt", "foo.txt");
+      buildShouldSucceed();
+    });
+
+    test("a transform stops consuming its input", () {
+      initGraph({
+        "app|foo.txt": "yes"
+      }, {
+        "app": [[
+          new ConditionallyConsumePrimaryTransformer("txt", "out", "yes")
+        ]]
+      });
+
+      updateSources(["app|foo.txt"]);
+      expectAsset("app|foo.out", "yes.out");
+      expectNoAsset("app|foo.txt");
+      buildShouldSucceed();
+
+      modifyAsset("app|foo.txt", "no");
+      updateSources(["app|foo.txt"]);
+      expectAsset("app|foo.out", "no.out");
+      expectAsset("app|foo.txt", "no");
+      buildShouldSucceed();
+    });
+
+    test("a transform stops consuming its input but a sibling is still "
+        "consuming it", () {

[Bob Nystrom, 2014/03/07 21:54:11]

It's a subset of this test, but it might be nice to have a standalone test
that's just two siblings consuming the same primary without any conditional
changes.

If nothing else, it makes it easier for a reader to learn the semantics by
working their way up from smaller tests to more complex ones.

[nweiz, 2014/03/11 21:44:05]

Done.

+      initGraph({
+        "app|foo.txt": "yes"
+      }, {
+        "app": [[
+          new RewriteTransformer("txt", "one")..consumePrimary = true,
+          new ConditionallyConsumePrimaryTransformer("txt", "two", "yes")
+        ]]
+      });
+
+      updateSources(["app|foo.txt"]);
+      expectAsset("app|foo.one", "yes.one");
+      expectAsset("app|foo.two", "yes.two");
+      expectNoAsset("app|foo.txt");
+      buildShouldSucceed();
+
+      modifyAsset("app|foo.txt", "no");
+      updateSources(["app|foo.txt"]);
+      expectAsset("app|foo.one", "no.one");
+      expectAsset("app|foo.two", "no.two");
+      expectNoAsset("app|foo.txt");
+      buildShouldSucceed();
+    });
+
+    test("a transform consumes its input and emits nothing", () {
+      initGraph([
+        "app|foo.txt"
+      ], {
+        "app": [[new EmitNothingTransformer("txt")..consumePrimary = true]]
+      });
+
+      updateSources(["app|foo.txt"]);
+      expectNoAsset("app|foo.txt");
+      buildShouldSucceed();
+    });
+
+    test("a transform consumes its input, then is removed", () {
+      initGraph([
+        "app|foo.txt"
+      ], {
+        "app": [[new RewriteTransformer("txt", "out")..consumePrimary = true]]
+      });
+
+      updateSources(["app|foo.txt"]);
+      expectAsset("app|foo.out", "foo.out");
+      expectNoAsset("app|foo.txt");
+      buildShouldSucceed();
+
+      updateTransformers("app", [[]]);
+      expectNoAsset("app|foo.out");
+      expectAsset("app|foo.txt", "foo");
+      buildShouldSucceed();
+    });
+
+    test("a transform consumes its input and emits nothing, then is removed",
+        () {
+      initGraph([
+        "app|foo.txt"
+      ], {
+        "app": [[new EmitNothingTransformer("txt")..consumePrimary = true]]
+      });
+
+      updateSources(["app|foo.txt"]);
+      expectNoAsset("app|foo.txt");
+      buildShouldSucceed();
+
+      updateTransformers("app", [[]]);
+      expectAsset("app|foo.txt", "foo");
+      buildShouldSucceed();
+    });
+ 
+    test("a transform which consumes its input is added", () {
+      initGraph([
+        "app|foo.txt"
+      ], {
+        "app": [[]]
+      });
+
+      updateSources(["app|foo.txt"]);
+      expectNoAsset("app|foo.out");
+      expectAsset("app|foo.txt", "foo");
+      buildShouldSucceed();
+
+      updateTransformers("app", [[
+        new RewriteTransformer("txt", "out")..consumePrimary = true
+      ]]);
+      expectAsset("app|foo.out", "foo.out");
+      expectNoAsset("app|foo.txt");
+      buildShouldSucceed();
+    });
+ });
 }