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packages/barback/test/transformer/mock.dart

Index: packages/barback/test/transformer/mock.dart
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+// Copyright (c) 2013, 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 barback.test.transformer.mock;
+
+import 'dart:async';
+
+import 'package:barback/barback.dart';
+import 'package:barback/src/utils.dart';
+import 'package:scheduled_test/scheduled_test.dart';
+
+/// The abstract base class for transformers used to test barback.
+///
+/// This adds the ability to pause and resume different components of the
+/// transformers, and to tell whether they're running, when they start running,
+/// and how many times they've run.
+///
+/// Transformers extending this should override [doIsPrimary] and [doApply]
+/// rather than [isPrimary] and [apply], and they should use [getInput] and
+/// [getPrimary] rather than [transform.getInput] and [transform.primaryInput].
+abstract class MockTransformer extends Transformer {
+  /// The number of times the transformer has been applied.
+  ///
+  /// This is scheduled. The Future will complete at the point in the schedule
+  /// that this is called.
+  Future<int> get numRuns => schedule(() => _numRuns);
+  var _numRuns = 0;
+
+  /// The number of currently running transforms.
+  int _runningTransforms = 0;
+
+  /// A completer for pausing the transformer before it finishes running
+  /// [apply].
+  Completer _apply;
+
+  /// Completers for pausing the transformer before it finishes running
+  /// [isPrimary].
+  final _isPrimary = new Map<AssetId, Completer>();
+
+  /// Completers for pausing the transformer before it finishes getting inputs
+  /// the [Transform].
+  final _getInput = new Map<AssetId, Completer>();
+
+  /// Completer for pausing the transformer before it accesses [primaryInput].
+  Completer _primaryInput;
+
+  /// A completer that completes once this transformer begins running.
+  ///
+  /// Once this transformer finishes running, this is reset to a new completer,
+  /// so it can be used multiple times.
+  var _started = new Completer();
+
+  /// `true` if any transforms are currently running.
+  ///
+  /// This is scheduled. The Future will complete at the point in the schedule
+  /// that this is called.
+  Future<bool> get isRunning => schedule(() => _runningTransforms > 0);
+
+  /// If this is set to `true`, the transformer will consume its primary input
+  /// during [apply].
+  bool consumePrimary = false;
+
+  /// Pauses the schedule until this transformer begins running.
+  void waitUntilStarted() {
+    schedule(() => _started.future, "wait until $this starts");
+  }
+
+  /// Causes the transformer to pause after running [apply] but before the
+  /// returned Future completes.
+  ///
+  /// This can be resumed by calling [resumeApply]. This operation is scheduled.
+  void pauseApply() {
+    schedule(() {
+      _apply = new Completer();
+    }, "pause apply for $this");
+  }
+
+  /// Resumes the transformer's [apply] call after [pauseApply] was called.
+  ///
+  /// This operation is scheduled.
+  void resumeApply() {
+    schedule(() {
+      _apply.complete();
+      _apply = null;
+    }, "resume apply for $this");
+  }
+
+  /// Causes the transformer to pause after running [isPrimary] on the asset
+  /// with the given [name], but before the returned Future completes.
+  ///
+  /// This can be resumed by calling [resumeIsPrimary]. This operation is
+  /// scheduled.
+  void pauseIsPrimary(String name) {
+    schedule(() {
+      _isPrimary[new AssetId.parse(name)] = new Completer();
+    }, "pause isPrimary($name) for $this");
+  }
+
+  /// Resumes the transformer's [isPrimary] call on the asset with the given
+  /// [name] after [pauseIsPrimary] was called.
+  ///
+  /// This operation is scheduled.
+  void resumeIsPrimary(String name) {
+    schedule(() {
+      _isPrimary.remove(new AssetId.parse(name)).complete();
+    }, "resume isPrimary($name) for $this");
+  }
+
+  /// Causes the transformer to pause while loading the secondary input with
+  /// the given [name].
+  ///
+  /// This can be resumed by calling [resumeGetInput]. This operation is
+  /// scheduled.
+  void pauseGetInput(String name) {
+    schedule(() {
+      _getInput[new AssetId.parse(name)] = new Completer();
+    }, "pause getInput($name) for $this");
+  }
+
+  /// Resumes the transformer's loading of the input with the given [name] after
+  /// [pauseGetInput] was called.
+  ///
+  /// This operation is scheduled.
+  void resumeGetInput(String name) {
+    schedule(() {
+      _getInput.remove(new AssetId.parse(name)).complete();
+    }, "resume getInput($name) for $this");
+  }
+
+  /// Causes the transformer to pause before accessing [primaryInput].
+  ///
+  /// This can be resumed by calling [resumeGetPrimary]. This operation is
+  /// scheduled.
+  void pausePrimaryInput() {
+    schedule(() {
+      _primaryInput = new Completer();
+    }, "pause primaryInput for $this");
+  }
+
+  /// Resumes the transformer's invocation of [primaryInput] after
+  /// [pauseGetPrimary] was called.
+  ///
+  /// This operation is scheduled.
+  void resumePrimaryInput() {
+    schedule(() {
+      _primaryInput.complete();
+      _primaryInput = null;
+    }, "resume getPrimary() for $this");
+  }
+
+  /// Like [Transform.getInput], but respects [pauseGetInput].
+  ///
+  /// This is intended for use by subclasses of [MockTransformer].
+  Future<Asset> getInput(Transform transform, AssetId id) {
+    return newFuture(() {
+      if (_getInput.containsKey(id)) return _getInput[id].future;
+    }).then((_) => transform.getInput(id));
+  }
+
+  /// Like [Transform.primaryInput], but respects [pauseGetPrimary].
+  ///
+  /// This is intended for use by subclasses of [MockTransformer].
+  Future<Asset> getPrimary(Transform transform) {
+    return newFuture(() {
+      if (_primaryInput != null) return _primaryInput.future;
+    }).then((_) => transform.primaryInput);
+  }
+
+  Future<bool> isPrimary(AssetId id) {
+    return newFuture(() => doIsPrimary(id)).then((result) {
+      return newFuture(() {
+        if (_isPrimary.containsKey(id)) {
+          return _isPrimary[id].future;
+        }
+      }).then((_) => result);
+    });
+  }
+
+  Future apply(Transform transform) {
+    _numRuns++;
+    if (_runningTransforms == 0) _started.complete();
+    _runningTransforms++;
+    if (consumePrimary) transform.consumePrimary();
+    return newFuture(() => doApply(transform)).then((_) {
+      if (_apply != null) return _apply.future;
+    }).whenComplete(() {
+      _runningTransforms--;
+      if (_runningTransforms == 0) _started = new Completer();
+    });
+  }
+
+  /// The wrapped version of [isPrimary] for subclasses to override.
+  ///
+  /// This may return a `Future<bool>` or, if it's entirely synchronous, a
+  /// `bool`.
+  doIsPrimary(AssetId id);
+
+  /// The wrapped version of [doApply] for subclasses to override.
+  ///
+  /// If this does asynchronous work, it should return a [Future] that completes
+  /// once it's finished.
+  doApply(Transform transform);
+}