Improve parallelism when loading transformer plugins.

sdk/lib/_internal/pub/test/transformers_needed_by_transformers/conservative_dependencies_test.dart

Index: sdk/lib/_internal/pub/test/transformers_needed_by_transformers/conservative_dependencies_test.dart
diff --git a/sdk/lib/_internal/pub/test/transformers_needed_by_transformers/conservative_dependencies_test.dart b/sdk/lib/_internal/pub/test/transformers_needed_by_transformers/conservative_dependencies_test.dart
new file mode 100644
index 0000000000000000000000000000000000000000..19118a6d5965e9b0ec223853b269bdcaa800d966
--- /dev/null
+++ b/sdk/lib/_internal/pub/test/transformers_needed_by_transformers/conservative_dependencies_test.dart
@@ -0,0 +1,466 @@
+// 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 'package:scheduled_test/scheduled_test.dart';
+
+import '../descriptor.dart' as d;
+import '../test_pub.dart';
+import 'utils.dart';
+
+void main() {
+  initConfig();
+
+  integration("reports previous transformers as dependencies if the "
+      "transformer is transformed", () {
+    // The root app just exists so that something is transformed by pkg and qux.
+    d.dir(appPath, [
+      d.pubspec({
+        "name": "myapp",
+        "version": "1.0.0",
+        "dependencies": {
+          "pkg": {"path": "../pkg"},
+          "qux": {"path": "../qux"}
+        },
+        "transformers": ["pkg", "qux"]
+      })
+    ]).create();
+
+    d.dir("pkg", [
+      d.pubspec({
+        "name": "pkg",
+        "version": "1.0.0",
+        "dependencies": {
+          "foo": {"path": "../foo"},
+          "bar": {"path": "../bar"},
+          "baz": {"path": "../baz"},
+        },
+        "transformers": [
+          {"foo": {"\$include": "lib/pkg.dart"}},
+          {"bar": {"\$exclude": "lib/transformer.dart"}},
+          "baz"
+        ]
+      }),
+      d.dir("lib", [
+        d.file("pkg.dart", ""),
+        d.file("transformer.dart", transformer())
+      ])
+    ]).create();
+
+    // Even though foo and bar don't modify pkg/lib/transformer.dart themselves,
+    // it may be modified to import a library that they modify or generate, so
+    // pkg will depend on them.
+    d.dir("foo", [
+      d.libPubspec("foo", "1.0.0"),
+      d.dir("lib", [d.file("foo.dart", transformer())])
+    ]).create();
+
+    d.dir("bar", [
+      d.libPubspec("bar", "1.0.0"),
+      d.dir("lib", [d.file("bar.dart", transformer())])
+    ]).create();
+
+    // baz transforms pkg/lib/transformer.dart, so pkg will obviously
+    // depend on it.
+    d.dir("baz", [
+      d.libPubspec("baz", "1.0.0"),
+      d.dir("lib", [d.file("baz.dart", transformer())])
+    ]).create();
+
+    // qux doesn't transform anything in pkg, so pkg won't depend on it.
+    d.dir("qux", [
+      d.libPubspec("qux", "1.0.0"),
+      d.dir("lib", [d.file("qux.dart", transformer())])
+    ]).create();
+
+    expectDependencies({
+      'pkg': ['foo', 'bar', 'baz'], 'foo': [], 'bar': [], 'baz': [], 'qux': []
+    });
+  });
+
+  integration("reports all transitive package dependencies' transformers as "
+      "dependencies if the transformer is transformed", () {
+    // The root app just exists so that something is transformed by pkg and qux.
+    d.dir(appPath, [
+      d.pubspec({
+        "name": "myapp",
+        "dependencies": {
+          "pkg": {"path": "../pkg"},
+          "qux": {"path": "../qux"}
+        },
+        "transformers": ["pkg"]
+      })
+    ]).create();
+
+    d.dir("pkg", [
+      d.pubspec({
+        "name": "pkg",
+        "version": "1.0.0",
+        "dependencies": {
+          "foo": {"path": "../foo"},
+          "baz": {"path": "../baz"}
+        },
+        "transformers": ["baz"]
+      }),
+      d.dir("lib", [d.file("pkg.dart", transformer())])
+    ]).create();
+
+    // pkg depends on foo. Even though it's not transformed by foo, its
+    // transformed transformer could import foo, so it has to depend on foo.
+    d.dir("foo", [
+      d.pubspec({
+        "name": "foo",
+        "version": "1.0.0",
+        "dependencies": {"bar": {"path": "../bar"}},
+        "transformers": ["foo"]
+      }),
+      d.dir("lib", [d.file("foo.dart", transformer())])
+    ]).create();
+
+    // foo depends on bar, and like pkg's dependency on foo, the transformed
+    // version of foo's transformer could import bar, so foo has to depend on
+    // bar.
+    d.dir("bar", [
+      d.pubspec({
+        "name": "bar",
+        "version": "1.0.0",
+        "transformers": ["bar"]
+      }),
+      d.dir("lib", [d.file("bar.dart", transformer())])
+    ]).create();
+
+    /// foo is transformed by baz.
+    d.dir("baz", [
+      d.libPubspec("baz", "1.0.0"),
+      d.dir("lib", [d.file("baz.dart", transformer())])
+    ]).create();
+
+    /// qux is not part of pkg's transitive dependency tree, so pkg shouldn't
+    /// depend on it.
+    d.dir("qux", [
+      d.pubspec({
+        "name": "qux",
+        "version": "1.0.0",
+        "transformers": ["qux"]
+      }),
+      d.dir("lib", [d.file("qux.dart", transformer())])
+    ]).create();
+
+    expectDependencies({
+      'pkg': ['foo', 'bar', 'baz'], 'foo': [], 'bar': [], 'baz': [], 'qux': []
+    });
+  });
+
+  integration("reports previous transformers as dependencies if a "
+      "nonexistent local file is imported", () {
+    // The root app just exists so that something is transformed by pkg and bar.
+    d.dir(appPath, [
+      d.pubspec({
+        "name": "myapp",
+        "dependencies": {
+          "pkg": {"path": "../pkg"},
+          "bar": {"path": "../bar"}
+        },
+        "transformers": ["pkg", "bar"]
+      })
+    ]).create();
+
+    d.dir("pkg", [
+      d.pubspec({
+        "name": "pkg",
+        "version": "1.0.0",
+        "dependencies": {
+          "foo": {"path": "../foo"},
+          "bar": {"path": "../bar"}
+        },
+        "transformers": [{"foo": {"\$include": "lib/pkg.dart"}}]
+      }),
+      d.dir("lib", [
+        d.file("pkg.dart", ""),
+        d.file("transformer.dart", transformer(["nonexistent.dart"]))
+      ])
+    ]).create();
+
+    // Since pkg's transformer imports a nonexistent file, we assume that file
+    // was generated by foo's transformer. Thus pkg's transformer depends on
+    // foo's even though the latter doesn't transform the former.
+    d.dir("foo", [
+      d.libPubspec("foo", "1.0.0"),
+      d.dir("lib", [d.file("foo.dart", transformer())])
+    ]).create();
+
+    /// qux is not part of pkg's transitive dependency tree, so pkg shouldn't
+    /// depend on it.
+    d.dir("bar", [
+      d.libPubspec("bar", "1.0.0"),
+      d.dir("lib", [d.file("bar.dart", transformer())])
+    ]).create();
+
+    expectDependencies({'pkg': ['foo'], 'foo': [], 'bar': []});
+  });
+
+  integration("reports all that package's dependencies' transformers as "
+      "dependencies if a non-existent file is imported from another package",
+      () {
+    d.dir(appPath, [
+      d.pubspec({
+        "name": "myapp",
+        "dependencies": {
+          "foo": {"path": "../foo"},
+          "qux": {"path": "../qux"}
+        },
+        "transformers": ["myapp"]
+      }),
+      d.dir("lib", [
+        d.file("myapp.dart", transformer(["package:foo/nonexistent.dart"]))
+      ])
+    ]).create();
+
+    // myapp imported a nonexistent file from foo so myapp will depend on every
+    // transformer transitively reachable from foo, since the nonexistent file
+    // could be generated to import anything.
+    d.dir("foo", [
+      d.pubspec({
+        "name": "foo",
+        "version": "1.0.0",
+        "dependencies": {
+          "bar": {"path": "../bar"},
+          "baz": {"path": "../baz"}
+        },
+        "transformers": ["foo"]
+      }),
+      d.dir("lib", [d.file("foo.dart", transformer())])
+    ]).create();
+
+    // bar is a dependency of foo so myapp will depend on it.
+    d.dir("bar", [
+      d.pubspec({
+        "name": "bar",
+        "version": "1.0.0",
+        "transformers": ["bar"]
+      }),
+      d.dir("lib", [d.file("bar.dart", transformer())])
+    ]).create();
+
+    // baz is a dependency of foo so myapp will depend on it.
+    d.dir("baz", [
+      d.pubspec({
+        "name": "baz",
+        "version": "1.0.0",
+        "transformers": ["baz"]
+      }),
+      d.dir("lib", [d.file("baz.dart", transformer())])
+    ]).create();
+
+    // qux is not transitively reachable from foo so myapp won't depend on it.
+    d.dir("qux", [
+      d.pubspec({
+        "name": "qux",
+        "version": "1.0.0",
+        "transformers": ["qux"]
+      }),
+      d.dir("lib", [d.file("qux.dart", transformer())])
+    ]).create();
+
+    expectDependencies({
+      'myapp': ['foo', 'bar', 'baz'], 'foo': [], 'bar': [], 'baz': [], 'qux': []
+    });
+  });
+
+  integration("reports all that package's dependencies' transformers as "
+      "dependencies if a non-existent transformer is used from another package",
+      () {
+    d.dir(appPath, [
+      d.pubspec({
+        "name": "myapp",
+        "dependencies": {
+          "foo": {"path": "../foo"},
+          "qux": {"path": "../qux"}
+        },
+        "transformers": ["myapp"]
+      }),
+      d.dir("lib", [
+        d.file("myapp.dart", transformer(["package:foo/nonexistent.dart"]))
+      ])
+    ]).create();
+
+    // myapp imported a nonexistent file from foo so myapp will depend on every
+    // transformer transitively reachable from foo, since the nonexistent file
+    // could be generated to import anything.
+    d.dir("foo", [
+      d.pubspec({
+        "name": "foo",
+        "version": "1.0.0",
+        "dependencies": {
+          "bar": {"path": "../bar"},
+          "baz": {"path": "../baz"}
+        },
+        "transformers": ["bar"]
+      })
+    ]).create();
+
+    // bar is a dependency of foo so myapp will depend on it.
+    d.dir("bar", [
+      d.libPubspec("bar", "1.0.0"),
+      d.dir("lib", [d.file("bar.dart", transformer())])
+    ]).create();
+
+    // baz is a dependency of foo so myapp will depend on it.
+    d.dir("baz", [
+      d.pubspec({
+        "name": "baz",
+        "version": "1.0.0",
+        "transformers": ["baz"]
+      }),
+      d.dir("lib", [d.file("baz.dart", transformer())])
+    ]).create();
+
+    // qux is not transitively reachable from foo so myapp won't depend on it.
+    d.dir("qux", [
+      d.pubspec({
+        "name": "qux",
+        "version": "1.0.0",
+        "transformers": ["qux"]
+      }),
+      d.dir("lib", [d.file("qux.dart", transformer())])
+    ]).create();
+
+    expectDependencies({
+      'myapp': ['bar', 'baz'], 'bar': [], 'baz': [], 'qux': []
+    });
+  });
+
+  test("reports dependencies on transformers in past phases", () {
+    d.dir(appPath, [
+      d.pubspec({
+        "name": "myapp",
+        "transformers": [
+          "myapp/first",
+          "myapp/second",
+          "myapp/third"
+        ]
+      }),
+      d.dir("lib", [
+        d.file("first.dart", transformer()),
+        d.file("second.dart", transformer()),
+        d.file("third.dart", transformer())
+      ])
+    ]).create();
+
+    expectDependencies({
+      'myapp/first': [],
+      'myapp/second': ['myapp/first'],
+      'myapp/third': ['myapp/second', 'myapp/first']
+    });
+  });
+
+  integration("considers the entrypoint package's dev and override "
+      "dependencies", () {
+    d.dir(appPath, [
+      d.pubspec({
+        "name": "myapp",
+        "dependencies": {"foo": {"path": "../foo"}},
+        "dev_dependencies": {"bar": {"path": "../bar"}},
+        "dependency_overrides": {"baz": {"path": "../baz"}},
+        "transformers": ["foo", "myapp"]
+      }),
+      d.dir("lib", [d.file("myapp.dart", transformer())])
+    ]).create();
+
+    // foo transforms myapp's transformer so it could import from bar or baz.
+    d.dir("foo", [
+      d.pubspec({
+        "name": "foo",
+        "version": "1.0.0",
+        "transformers": ["foo"]
+      }),
+      d.dir("lib", [d.file("foo.dart", transformer())])
+    ]).create();
+
+    // bar is a dev dependency that myapp could import from, so myapp should
+    // depend on it.
+    d.dir("bar", [
+      d.pubspec({
+        "name": "bar",
+        "version": "1.0.0",
+        "transformers": ["bar"]
+      }),
+      d.dir("lib", [d.file("bar.dart", transformer())])
+    ]).create();
+
+    // baz is an override dependency that myapp could import from, so myapp
+    // should depend on it.
+    d.dir("baz", [
+      d.pubspec({
+        "name": "baz",
+        "version": "1.0.0",
+        "transformers": ["baz"]
+      }),
+      d.dir("lib", [d.file("baz.dart", transformer())])
+    ]).create();
+
+    expectDependencies({
+      'myapp': ['foo', 'bar', 'baz'], 'foo': [], 'bar': [], 'baz': []
+    });
+  });
+
+  integration("doesn't consider a non-entrypoint package's dev and override "
+      "dependencies", () {
+    // myapp just exists so that pkg isn't the entrypoint.
+    d.dir(appPath, [
+      d.pubspec({
+        "name": "myapp",
+        "dependencies": {"pkg": {"path": "../pkg"}}
+      })
+    ]).create();
+
+    d.dir("pkg", [
+      d.pubspec({
+        "name": "pkg",
+        "dependencies": {"foo": {"path": "../foo"}},
+        "dev_dependencies": {"bar": {"path": "../bar"}},
+        "dependency_overrides": {"baz": {"path": "../baz"}},
+        "transformers": ["foo", "pkg"]
+      }),
+      d.dir("lib", [d.file("pkg.dart", transformer())])
+    ]).create();
+
+    // foo transforms pkg's transformer so it could theoretcially import from
+    // bar or baz. However, since pkg isn't the entrypoint, it doesn't have
+    // access to them.
+    d.dir("foo", [
+      d.pubspec({
+        "name": "foo",
+        "version": "1.0.0",
+        "transformers": ["foo"]
+      }),
+      d.dir("lib", [d.file("foo.dart", transformer())])
+    ]).create();
+
+    // bar is a dev dependency that myapp can't import from, so myapp shouldn't
+    // depend on it.
+    d.dir("bar", [
+      d.pubspec({
+        "name": "bar",
+        "version": "1.0.0",
+        "transformers": ["bar"]
+      }),
+      d.dir("lib", [d.file("bar.dart", transformer())])
+    ]).create();
+
+    // baz is a dev dependency that myapp can't import from, so myapp shouldn't
+    // depend on it.
+    d.dir("baz", [
+      d.pubspec({
+        "name": "baz",
+        "version": "1.0.0",
+        "transformers": ["baz"]
+      }),
+      d.dir("lib", [d.file("baz.dart", transformer())])
+    ]).create();
+
+    expectDependencies({'pkg': ['foo'], 'foo': [], 'bar': [], 'baz': []});
+  });
+}