Add an override_platforms config field

See #391

CHANGELOG.md

@@ -1,3 +1,12 @@
+## 0.12.25
+
+* Add a `override_platforms` configuration field which allows test platforms'
+  settings (such as browsers' executables) to be overridden by the user.
+
+* Add a `define_platforms` configuration field which makes it possible to define
+  new platforms that use the same logic as existing ones but have different
+  settings.
+
 ## 0.12.24+8
 
 * `spawnHybridUri()` now interprets relative URIs correctly in browser tests.

doc/configuration.md

@@ -52,7 +52,8 @@ tags:
 * [Configuring Platforms](#configuring-platforms)
   * [`on_os`](#on_os)
   * [`on_platform`](#on_platform)
-  * [`define_platform`](#define_platform)
+  * [`override_platforms`](#override_platforms)
+  * [`define_platforms`](#define_platforms)
   * [Browser Settings](#browser-settings)
     * [`executable`](#executable)
 * [Configuration Presets](#configuration-presets)
@@ -570,6 +571,26 @@ when running on a particular operating system, use [`on_os`](#on_os) instead.
 
 This field counts as [test configuration](#test-configuration).
 
+### `override_platforms`
+
+This field allows you to customize the settings for built-in test platforms. It
+takes a map from platform identifiers to settings for those platforms. For example:
+
+```yaml
+override_platforms:
+  chrome:
+    # The settings to override for this platform.
+    settings:
+      executable: chromium
+```
+
+This tells the test runner to use the `chromium` executable for Chrome tests. It
+calls that executable with the same logic and flags it normally uses for Chrome.
+
+Each platform can define exactly which settings it supports. All browsers
+support [the same settings](#browser-settings), but the VM doesn't support any
+settings and so can't be overridden.
+
 ### `define_platforms`
 
 You can define new platforms in terms of old ones using the `define_platforms`

lib/src/runner/browser/platform.dart

@@ -202,6 +202,9 @@ class BrowserPlatform extends PlatformPlugin
   ExecutableSettings parsePlatformSettings(YamlMap settings) =>
       new ExecutableSettings.parse(settings);
 
+  ExecutableSettings mergePlatformSettings(ExecutableSettings settings1, ExecutableSettings settings2) =>
+      settings1.merge(settings2);
+
   void customizePlatform(TestPlatform platform, ExecutableSettings settings) {
     var oldSettings =
         _browserSettings[platform] ?? _browserSettings[platform.root];

lib/src/runner/configuration.dart

@@ -8,6 +8,7 @@ import 'package:boolean_selector/boolean_selector.dart';
 import 'package:collection/collection.dart';
 import 'package:glob/glob.dart';
 import 'package:path/path.dart' as p;
+import 'package:source_span/source_span.dart';
 
 import '../backend/platform_selector.dart';
 import '../backend/test_platform.dart';
@@ -18,6 +19,7 @@ import 'configuration/args.dart' as args;
 import 'configuration/custom_platform.dart';
 import 'configuration/load.dart';
 import 'configuration/platform_selection.dart';
+import 'configuration/platform_settings.dart';
 import 'configuration/reporters.dart';
 import 'configuration/suite.dart';
 import 'configuration/values.dart';
@@ -172,6 +174,9 @@ class Configuration {
 
   Set<String> _knownPresets;
 
+  /// Built-in platforms whose settings are overridden by the user.
+  final Map<String, PlatformSettings> overridePlatforms;
+
   /// Platforms defined by the user in terms of existing platforms.
   final Map<String, CustomPlatform> definePlatforms;
 
@@ -218,6 +223,7 @@ class Configuration {
       Glob filename,
       Iterable<String> chosenPresets,
       Map<String, Configuration> presets,
+      Map<String, PlatformSettings> overridePlatforms,
       Map<String, CustomPlatform> definePlatforms,
       bool noRetry,
 
@@ -261,6 +267,7 @@ class Configuration {
         filename: filename,
         chosenPresets: chosenPresetSet,
         presets: _withChosenPresets(presets, chosenPresetSet),
+        overridePlatforms: overridePlatforms,
         definePlatforms: definePlatforms,
         noRetry: noRetry,
         suiteDefaults: new SuiteConfiguration(
@@ -316,6 +323,7 @@ class Configuration {
       Glob filename,
       Iterable<String> chosenPresets,
       Map<String, Configuration> presets,
+      Map<String, PlatformSettings> overridePlatforms,
       Map<String, CustomPlatform> definePlatforms,
       bool noRetry,
       SuiteConfiguration suiteDefaults})
@@ -337,6 +345,7 @@ class Configuration {
         chosenPresets =
             new UnmodifiableSetView(chosenPresets?.toSet() ?? new Set()),
         presets = _map(presets),
+        overridePlatforms = _map(overridePlatforms),
         definePlatforms = _map(definePlatforms),
         _noRetry = noRetry,
         suiteDefaults = pauseAfterLoad == true
@@ -399,6 +408,13 @@ class Configuration {
     // We don't need to verify [customPlatforms] here because those platforms
     // already need to be verified and resolved to create [allPlatforms].
 
+    for (var settings in overridePlatforms.values) {
+      if (!allPlatforms.any((platform) => platform.identifier == settings.identifier)) {
+        throw new SourceSpanFormatException(
+            'Unknown platform "${settings.identifier}".', settings.identifierSpan);
+      }
+    }
+
     suiteDefaults.validatePlatforms(allPlatforms);
     for (var config in presets.values) {
       config.validatePlatforms(allPlatforms);
@@ -448,6 +464,12 @@ class Configuration {
         filename: other._filename ?? _filename,
         chosenPresets: chosenPresets.union(other.chosenPresets),
         presets: _mergeConfigMaps(presets, other.presets),
+        overridePlatforms: mergeUnmodifiableMaps(
+            overridePlatforms, other.overridePlatforms,
+            value: (settings1, settings2) => new PlatformSettings(
+                settings1.identifier,
+                settings1.identifierSpan,
+                settings1.settings.toList()..addAll(settings2.settings))),
         definePlatforms:
             mergeUnmodifiableMaps(definePlatforms, other.definePlatforms),
         noRetry: other._noRetry ?? _noRetry,
@@ -482,6 +504,7 @@ class Configuration {
       Glob filename,
       Iterable<String> chosenPresets,
       Map<String, Configuration> presets,
+        Map<String, PlatformSettings> overridePlatforms,
       Map<String, CustomPlatform> definePlatforms,
       bool noRetry,
 
@@ -523,6 +546,7 @@ class Configuration {
         filename: filename ?? _filename,
         chosenPresets: chosenPresets ?? this.chosenPresets,
         presets: presets ?? this.presets,
+        overridePlatforms: overridePlatforms ?? this.overridePlatforms,
         definePlatforms: definePlatforms ?? this.definePlatforms,
         noRetry: noRetry ?? _noRetry,
         suiteDefaults: suiteDefaults.change(

lib/src/runner/configuration/load.dart

@@ -20,6 +20,7 @@ import '../configuration.dart';
 import '../configuration/suite.dart';
 import 'custom_platform.dart';
 import 'platform_selection.dart';
+import 'platform_settings.dart';
 import 'reporters.dart';
 
 /// A regular expression matching a Dart identifier.
@@ -193,6 +194,7 @@ class _ConfigurationLoader {
       _disallow("plain_names");
       _disallow("platforms");
       _disallow("add_presets");
+      _disallow("override_platforms");
       return Configuration.empty;
     }
 
@@ -215,13 +217,42 @@ class _ConfigurationLoader {
     var chosenPresets = _getList("add_presets",
         (presetNode) => _parseIdentifierLike(presetNode, "Preset name"));
 
+    var overridePlatforms = _loadOverridePlatforms();
+
     return new Configuration(
         pauseAfterLoad: pauseAfterLoad,
         runSkipped: runSkipped,
         reporter: reporter,
         concurrency: concurrency,
         platforms: platforms,
-        chosenPresets: chosenPresets);
+        chosenPresets: chosenPresets,
+        overridePlatforms: overridePlatforms);
+  }
+
+  /// Loads the `override_platforms` field.
+  Map<String, PlatformSettings> _loadOverridePlatforms() {
+    var platformsNode =
+        _getNode("override_platforms", "map", (value) => value is Map) as YamlMap;
+    if (platformsNode == null) return const {};
+
+    var platforms = <String, PlatformSettings>{};
+    platformsNode.nodes.forEach((identifierNode, valueNode) {
+      var identifier =
+          _parseIdentifierLike(identifierNode, "Platform identifier");
+
+      _validate(valueNode, "Platform definition must be a map.",
+          (value) => value is Map);
+      var map = valueNode as YamlMap;
+
+      var settings = _expect(map, "settings");
+      _validate(settings, "Must be a map.", (value) => value is Map);
+
+      platforms[identifier] = new PlatformSettings(
+          identifier,
+          identifierNode.span,
+          [settings as YamlMap]);
+    });
+    return platforms;
   }
 
   /// Loads runner configuration that's not allowed in the global configuration
@@ -316,6 +347,7 @@ class _ConfigurationLoader {
     });
   }
 
+  /// Loads the `define_platforms` field.
   Map<String, CustomPlatform> _loadDefinePlatforms() {
     var platformsNode =
         _getNode("define_platforms", "map", (value) => value is Map) as YamlMap;

lib/src/runner/configuration/platform_settings.dart

@@ -0,0 +1,26 @@
+// Copyright (c) 2017, 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.
+
+import 'package:source_span/source_span.dart';
+import 'package:yaml/yaml.dart';
+
+import '../plugin/customizable_platform.dart';
+
+/// User-defined settings for a built-in test platform.
+class PlatformSettings {
+  /// The identifier used to look up the platform being overridden.
+  final String identifier;
+
+  /// The location that [identifier] was defined in the configuration file.
+  final SourceSpan identifierSpan;
+
+  /// The user's settings for this platform.
+  ///
+  /// This is a list of settings, from most global to most specific, that will
+  /// eventually be merged using [CustomizablePlatform.mergePlatformSettings].
+  final List<YamlMap> settings;
+
+  PlatformSettings(this.identifier, this.identifierSpan, List<YamlMap> settings)
+      : settings = new List.unmodifiable(settings);
+}

lib/src/runner/loader.dart

@@ -53,8 +53,9 @@ class Loader {
   /// their string identifiers.
   final _platformsByIdentifier = <String, TestPlatform>{};
 
-  /// The user-provided settings for platforms.
-  final _platformSettings = <TestPlatform, YamlMap>{};
+  /// The user-provided settings for platforms, as a list of settings that will
+  /// be merged together using [CustomizablePlatform.mergePlatformSettings].
+  final _platformSettings = <TestPlatform, List<YamlMap>>{};
 
   /// The user-provided settings for platforms.
   final _parsedPlatformSettings = <TestPlatform, Object>{};
@@ -104,6 +105,8 @@ class Loader {
     _registerCustomPlatforms();
 
     _config.validatePlatforms(allPlatforms);
+
+    _registerPlatformOverrides();
   }
 
   /// Registers a [PlatformPlugin] for [platforms].
@@ -140,7 +143,19 @@ class Loader {
       _platformCallbacks[platform] = _platformCallbacks[parent];
       _platformsByIdentifier[platform.identifier] = platform;
 
-      _platformSettings[platform] = customPlatform.settings;
+      _platformSettings[platform] = [customPlatform.settings];
+    }
+  }
+
+  /// Registers users' platform settings from [Configuration.overridePlatforms].
+  void _registerPlatformOverrides() {
+    for (var settings in _config.overridePlatforms.values) {
+      var platform = _platformsByIdentifier[settings.identifier];
+
+      // This is officially validated in [Configuration.validatePlatforms].
+      assert(platform != null);
+
+      _platformSettings.putIfAbsent(platform, () => []).addAll(settings.settings);
     }
   }
 
@@ -258,7 +273,7 @@ class Loader {
     if (settings == null) return;
 
     if (plugin is CustomizablePlatform) {
-      parsed = plugin.parsePlatformSettings(settings);
+      parsed = settings.map(plugin.parsePlatformSettings).reduce(plugin.mergePlatformSettings);
       plugin.customizePlatform(platform, parsed);
       _parsedPlatformSettings[platform] = parsed;
     } else {
@@ -268,9 +283,8 @@ class Loader {
         identifier = platform.parent.identifier;
         span = _config.definePlatforms[platform.identifier].parentSpan;
       } else {
-        // TODO(nweiz): Get information from [_config.overridePlatforms] when
-        // that exists.
-        throw new UnimplementedError();
+        identifier = platform.identifier;
+        span = _config.overridePlatforms[platform.identifier].identifierSpan;
       }
 
       throw new SourceSpanFormatException(

lib/src/runner/plugin/customizable_platform.dart

@@ -34,6 +34,15 @@ abstract class CustomizablePlatform<T> extends PlatformPlugin {
   /// possible.
   T parsePlatformSettings(YamlMap settings);
 
+  /// Merges [settings1] with [settings2] and returns a new settings object that
+  /// includes the configuration of both.
+  ///
+  /// When the settings conflict, [settings2] should take priority.
+  ///
+  /// This is used to merge global settings with local settings, or a custom
+  /// platform's settings with its parent's.
+  T mergePlatformSettings(T settings1, T settings2);
+
   /// Defines user-provided [settings] for [platform].
   ///
   /// The [platform] is a platform this plugin was declared to accept when

lib/src/utils.dart

@@ -199,10 +199,11 @@ List flatten(Iterable nested) {
 /// creating a new map unnecessarily.
 ///
 /// The return value *may or may not* be unmodifiable.
-Map<K, V> mergeUnmodifiableMaps<K, V>(Map<K, V> map1, Map<K, V> map2) {
+Map<K, V> mergeUnmodifiableMaps<K, V>(Map<K, V> map1, Map<K, V> map2,
+    {V value(V value1, V value2)}) {
   if (map1.isEmpty) return map2;
   if (map2.isEmpty) return map1;
-  return mergeMaps(map1, map2);
+  return mergeMaps(map1, map2, value: value);
 }
 
 /// Truncates [text] to fit within [maxLength].

pubspec.yaml

@@ -1,5 +1,5 @@
 name: test
-version: 0.12.24+8
+version: 0.12.25-dev
 author: Dart Team <[email protected]>
 description: A library for writing dart unit tests.
 homepage: https://github.com/dart-lang/test