Use precompiled dependencies in pub.

sdk/lib/_internal/pub/test/get/cache_transformed_dependency_test.dart

Index: sdk/lib/_internal/pub/test/get/cache_transformed_dependency_test.dart
diff --git a/sdk/lib/_internal/pub/test/get/cache_transformed_dependency_test.dart b/sdk/lib/_internal/pub/test/get/cache_transformed_dependency_test.dart
index 86c3baa4b94f2e06d8a37d2922a9e0ba8168f62e..f3769eed49862342b5d090a3d53830a179609fbf 100644
--- a/sdk/lib/_internal/pub/test/get/cache_transformed_dependency_test.dart
+++ b/sdk/lib/_internal/pub/test/get/cache_transformed_dependency_test.dart
@@ -237,44 +237,83 @@ main() {
     ]).validate();
   });
 
-  // TODO(nweiz): Implement this.
-  // integration("loads code from the cache", () {
-  //   servePackages((builder) {
-  //     builder.serveRepoPackage('barback');
-  //
-  //     builder.serve("foo", "1.2.3",
-  //         deps: {'barback': 'any'},
-  //         pubspec: {'transformers': ['foo']},
-  //         contents: [
-  //       d.dir("lib", [
-  //         d.file("transformer.dart", replaceTransformer("Hello", "Goodbye")),
-  //         d.file("foo.dart", "final message = 'Hello!';")
-  //       ])
-  //     ]);
-  //   });
-  //
-  //   d.dir(appPath, [
-  //     d.appPubspec({"foo": "1.2.3"}),
-  //     d.dir('bin', [
-  //       d.file('script.dart', """
-  //         import 'package:foo/foo.dart';
-  //
-  //         void main() => print(message);""")
-  //     ])
-  //   ]).create();
-  //
-  //   pubGet(output: contains("Precompiled foo."));
-  //
-  //   d.dir(appPath, [
-  //     d.dir(".pub/deps/debug/foo/lib", [
-  //       d.file("foo.dart", "final message = 'Modified!';")
-  //     ])
-  //   ]).create();
-  //
-  //   var pub = pubRun(args: ["script"]);
-  //   pub.stdout.expect("Modified!");
-  //   pub.shouldExit();
-  // });
+  integration("loads code from the cache", () {
+    servePackages((builder) {
+      builder.serveRepoPackage('barback');
+
+      builder.serve("foo", "1.2.3",
+          deps: {'barback': 'any'},
+          pubspec: {'transformers': ['foo']},
+          contents: [
+        d.dir("lib", [
+          d.file("transformer.dart", replaceTransformer("Hello", "Goodbye")),
+          d.file("foo.dart", "final message = 'Hello!';")
+        ])
+      ]);
+    });
+
+    d.dir(appPath, [
+      d.appPubspec({"foo": "1.2.3"}),
+      d.dir('bin', [
+        d.file('script.dart', """
+          import 'package:foo/foo.dart';
+
+          void main() => print(message);""")
+      ])
+    ]).create();
+
+    pubGet(output: contains("Precompiled foo."));
+
+    d.dir(appPath, [
+      d.dir(".pub/deps/debug/foo/lib", [
+        d.file("foo.dart", "final message = 'Modified!';")
+      ])
+    ]).create();
+
+    var pub = pubRun(args: ["script"]);
+    pub.stdout.expect("Modified!");
+    pub.shouldExit();
+  });
+
+  integration("doesn't re-transform code loaded from the cache", () {
+    servePackages((builder) {
+      builder.serveRepoPackage('barback');
+
+      builder.serve("foo", "1.2.3",
+          deps: {'barback': 'any'},
+          pubspec: {'transformers': ['foo']},
+          contents: [
+        d.dir("lib", [
+          d.file("transformer.dart", replaceTransformer("Hello", "Goodbye")),
+          d.file("foo.dart", "final message = 'Hello!';")
+        ])
+      ]);
+    });
+
+    d.dir(appPath, [
+      d.appPubspec({"foo": "1.2.3"}),
+      d.dir('bin', [
+        d.file('script.dart', """
+          import 'package:foo/foo.dart';
+
+          void main() => print(message);""")
+      ])
+    ]).create();
+
+    pubGet(output: contains("Precompiled foo."));
+
+    // Manually reset the cache to its original state to prove that the
+    // transformer won't be run again on it.
+    d.dir(appPath, [
+      d.dir(".pub/deps/debug/foo/lib", [
+        d.file("foo.dart", "final message = 'Hello!';")
+      ])
+    ]).create();
+
+    var pub = pubRun(args: ["script"]);
+    pub.stdout.expect("Hello!");
+    pub.shouldExit();
+  });
 }
 
 String replaceTransformer(String input, String output) {