Don't load transformers that aren't going to be used for an executable.

sdk/lib/_internal/pub/test/dependency_computer/transformers_needed_by_library_test.dart

Index: sdk/lib/_internal/pub/test/dependency_computer/transformers_needed_by_library_test.dart
diff --git a/sdk/lib/_internal/pub/test/dependency_computer/transformers_needed_by_library_test.dart b/sdk/lib/_internal/pub/test/dependency_computer/transformers_needed_by_library_test.dart
new file mode 100644
index 0000000000000000000000000000000000000000..724307c29b70644c679130d1941ecc7c49eb0704
--- /dev/null
+++ b/sdk/lib/_internal/pub/test/dependency_computer/transformers_needed_by_library_test.dart
@@ -0,0 +1,115 @@
+// Copyright (c) 2014, 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 pub_tests;
+
+import '../descriptor.dart' as d;
+import '../test_pub.dart';
+import 'utils.dart';
+
+void main() {
+  initConfig();
+
+  integration("reports a dependency if the library itself is transformed", () {
+    d.dir(appPath, [
+      d.pubspec({
+        "name": "myapp",
+        "dependencies": {"foo": {"path": "../foo"}},
+        "transformers": [
+          {"foo": {"\$include": "bin/myapp.dart.dart"}}
+        ]
+      }),
+      d.dir("bin", [
+        d.file("myapp.dart", "import 'package:myapp/lib.dart';"),
+      ])
+    ]).create();
+
+    d.dir("foo", [
+      d.pubspec({"name": "foo", "version": "1.0.0"}),
+      d.dir("lib", [d.file("foo.dart", transformer())])
+    ]).create();
+
+    expectLibraryDependencies('myapp|bin/myapp.dart', ['foo']);
+  });
+
+  integration("reports a dependency if a transformed local file is imported",
+      () {
+    d.dir(appPath, [
+      d.pubspec({
+        "name": "myapp",
+        "dependencies": {"foo": {"path": "../foo"}},
+        "transformers": [
+          {"foo": {"\$include": "lib/lib.dart"}}
+        ]
+      }),
+      d.dir("lib", [
+        d.file("lib.dart", ""),
+      ]),
+      d.dir("bin", [
+        d.file("myapp.dart", "import 'package:myapp/lib.dart';"),
+      ])
+    ]).create();
+
+    d.dir("foo", [
+      d.pubspec({"name": "foo", "version": "1.0.0"}),
+      d.dir("lib", [d.file("foo.dart", transformer())])
+    ]).create();
+
+    expectLibraryDependencies('myapp|bin/myapp.dart', ['foo']);
+  });
+
+  integration("reports a dependency if a transformed foreign file is imported",
+      () {
+    d.dir(appPath, [
+      d.pubspec({
+        "name": "myapp",
+        "dependencies": {"foo": {"path": "../foo"}},
+      }),
+      d.dir("bin", [
+        d.file("myapp.dart", "import 'package:foo/foo.dart';")
+      ])
+    ]).create();
+
+    d.dir("foo", [
+      d.pubspec({
+        "name": "foo",
+        "version": "1.0.0",
+        "transformers": [{"foo": {"\$include": "lib/foo.dart"}}]
+      }),
+      d.dir("lib", [
+        d.file("foo.dart", ""),
+        d.file("transformer.dart", transformer())
+      ])
+    ]).create();
+
+    expectLibraryDependencies('myapp|bin/myapp.dart', ['foo']);
+  });
+
+  integration("doesn't report a dependency if no transformed files are "
+      "imported", () {
+    d.dir(appPath, [
+      d.pubspec({
+        "name": "myapp",
+        "dependencies": {"foo": {"path": "../foo"}},
+        "transformers": [
+          {"foo": {"\$include": "lib/lib.dart"}}
+        ]
+      }),
+      d.dir("lib", [
+        d.file("lib.dart", ""),
+        d.file("untransformed.dart", ""),
+      ]),
+      d.dir("bin", [
+        d.file("myapp.dart", "import 'package:myapp/untransformed.dart';"),
+      ])
+    ]).create();
+
+    d.dir("foo", [
+      d.pubspec({"name": "foo", "version": "1.0.0"}),
+      d.dir("lib", [d.file("foo.dart", transformer())])
+    ]).create();
+
+    expectLibraryDependencies('myapp|bin/myapp.dart', []);
+  });
+}