pkgs/test_core/lib/src/runner/suite.dart - test - Git at Google

 // Copyright (c) 2016, 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:boolean_selector/boolean_selector.dart';
 import 'package:collection/collection.dart';
 import 'package:source_span/source_span.dart';

 import 'package:test_api/src/backend/metadata.dart'; // ignore: implementation_imports
 import 'package:test_api/src/backend/platform_selector.dart'; // ignore: implementation_imports
 import 'package:test_api/src/backend/suite_platform.dart'; // ignore: implementation_imports
 import 'package:test_api/src/backend/runtime.dart'; // ignore: implementation_imports
 import 'package:test_api/src/frontend/timeout.dart'; // ignore: implementation_imports

 import 'runtime_selection.dart';

 /// Suite-level configuration.
 ///
 /// This tracks configuration that can differ from suite to suite.
 class SuiteConfiguration {
   /// Empty configuration with only default values.
   ///
   /// Using this is slightly more efficient than manually constructing a new
   /// configuration with no arguments.
   static final empty = SuiteConfiguration._();

   /// Whether JavaScript stack traces should be left as-is or converted to
   /// Dart-like traces.
   bool get jsTrace => _jsTrace ?? false;
   final bool _jsTrace;

   /// Whether skipped tests should be run.
   bool get runSkipped => _runSkipped ?? false;
   final bool _runSkipped;

   /// The path to a mirror of this package containing HTML that points to
   /// precompiled JS.
   ///
   /// This is used by the internal Google test runner so that test compilation
   /// can more effectively make use of Google's build tools.
   final String precompiledPath;

   /// Additional arguments to pass to dart2js.
   ///
   /// Note that this if multiple suites run the same JavaScript on different
   /// runtimes, and they have different [dart2jsArgs], only one (undefined)
   /// suite's arguments will be used.
   final List<String> dart2jsArgs;

   /// The patterns to match against test names to decide which to run, or `null`
   /// if all tests should be run.
   ///
   /// All patterns must match in order for a test to be run.
   final Set<Pattern> patterns;

   /// The set of runtimes on which to run tests.
   List<String> get runtimes => _runtimes == null
       ? const ['vm']
       : List.unmodifiable(_runtimes.map((runtime) => runtime.name));
   final List<RuntimeSelection> _runtimes;

   /// Only run tests whose tags match this selector.
   ///
   /// When [merge]d, this is intersected with the other configuration's included
   /// tags.
   final BooleanSelector includeTags;

   /// Do not run tests whose tags match this selector.
   ///
   /// When [merge]d, this is unioned with the other configuration's
   /// excluded tags.
   final BooleanSelector excludeTags;

   /// Configuration for particular tags.
   ///
   /// The keys are tag selectors, and the values are configurations for tests
   /// whose tags match those selectors.
   final Map<BooleanSelector, SuiteConfiguration> tags;

   /// Configuration for particular platforms.
   ///
   /// The keys are platform selectors, and the values are configurations for
   /// those platforms. These configuration should only contain test-level
   /// configuration fields, but that isn't enforced.
   final Map<PlatformSelector, SuiteConfiguration> onPlatform;

   /// The seed with which to shuffle the test order.
   /// Default value is null if not provided and will not change the test order.
   /// The same seed will shuffle the tests in the same way every time.
   final int testRandomizeOrderingSeed;

   /// The global test metadata derived from this configuration.
   Metadata get metadata {
     if (tags.isEmpty && onPlatform.isEmpty) return _metadata;
     return _metadata.change(
         forTag: tags.map((key, config) => MapEntry(key, config.metadata)),
         onPlatform:
             onPlatform.map((key, config) => MapEntry(key, config.metadata)));
   }

   final Metadata _metadata;

   /// The set of tags that have been declared in any way in this configuration.
   Set<String> get knownTags {
     if (_knownTags != null) return _knownTags;

     var known = includeTags.variables.toSet()
       ..addAll(excludeTags.variables)
       ..addAll(_metadata.tags);

     for (var selector in tags.keys) {
       known.addAll(selector.variables);
     }

     for (var configuration in _children) {
       known.addAll(configuration.knownTags);
     }

     _knownTags = UnmodifiableSetView(known);
     return _knownTags;
   }

   Set<String> _knownTags;

   /// All child configurations of [this] that may be selected under various
   /// circumstances.
   Iterable<SuiteConfiguration> get _children sync* {
     yield* tags.values;
     yield* onPlatform.values;
   }

   factory SuiteConfiguration(
       {bool jsTrace,
       bool runSkipped,
       Iterable<String> dart2jsArgs,
       String precompiledPath,
       Iterable<Pattern> patterns,
       Iterable<RuntimeSelection> runtimes,
       BooleanSelector includeTags,
       BooleanSelector excludeTags,
       Map<BooleanSelector, SuiteConfiguration> tags,
       Map<PlatformSelector, SuiteConfiguration> onPlatform,
       int testRandomizeOrderingSeed,

       // Test-level configuration
       Timeout timeout,
       bool verboseTrace,
       bool chainStackTraces,
       bool skip,
       int retry,
       String skipReason,
       PlatformSelector testOn,
       Iterable<String> addTags}) {
     var config = SuiteConfiguration._(
         jsTrace: jsTrace,
         runSkipped: runSkipped,
         dart2jsArgs: dart2jsArgs,
         precompiledPath: precompiledPath,
         patterns: patterns,
         runtimes: runtimes,
         includeTags: includeTags,
         excludeTags: excludeTags,
         tags: tags,
         onPlatform: onPlatform,
         testRandomizeOrderingSeed: testRandomizeOrderingSeed,
         metadata: Metadata(
             timeout: timeout,
             verboseTrace: verboseTrace,
             chainStackTraces: chainStackTraces,
             skip: skip,
             retry: retry,
             skipReason: skipReason,
             testOn: testOn,
             tags: addTags));
     return config._resolveTags();
   }

   /// Creates new SuiteConfiguration.
   ///
   /// Unlike [new SuiteConfiguration], this assumes [tags] is already
   /// resolved.
   SuiteConfiguration._(
       {bool jsTrace,
       bool runSkipped,
       Iterable<String> dart2jsArgs,
       this.precompiledPath,
       Iterable<Pattern> patterns,
       Iterable<RuntimeSelection> runtimes,
       BooleanSelector includeTags,
       BooleanSelector excludeTags,
       Map<BooleanSelector, SuiteConfiguration> tags,
       Map<PlatformSelector, SuiteConfiguration> onPlatform,
       int testRandomizeOrderingSeed,
       Metadata metadata})
       : _jsTrace = jsTrace,
         _runSkipped = runSkipped,
         dart2jsArgs = _list(dart2jsArgs) ?? const [],
         patterns = UnmodifiableSetView(patterns?.toSet() ?? {}),
         _runtimes = _list(runtimes),
         includeTags = includeTags ?? BooleanSelector.all,
         excludeTags = excludeTags ?? BooleanSelector.none,
         tags = _map(tags),
         onPlatform = _map(onPlatform),
         testRandomizeOrderingSeed = testRandomizeOrderingSeed,
         _metadata = metadata ?? Metadata.empty;

   /// Creates a new [SuiteConfiguration] that takes its configuration from
   /// [metadata].
   factory SuiteConfiguration.fromMetadata(Metadata metadata) =>
       SuiteConfiguration._(
           tags: metadata.forTag.map((key, child) =>
               MapEntry(key, SuiteConfiguration.fromMetadata(child))),
           onPlatform: metadata.onPlatform.map((key, child) =>
               MapEntry(key, SuiteConfiguration.fromMetadata(child))),
           metadata: metadata.change(forTag: {}, onPlatform: {}));

   /// Returns an unmodifiable copy of [input].
   ///
   /// If [input] is `null` or empty, this returns `null`.
   static List<T> _list<T>(Iterable<T> input) {
     if (input == null) return null;
     var list = List<T>.unmodifiable(input);
     if (list.isEmpty) return null;
     return list;
   }

   /// Returns an unmodifiable copy of [input] or an empty unmodifiable map.
   static Map<K, V> _map<K, V>(Map<K, V> input) {
     if (input == null || input.isEmpty) return const {};
     return Map.unmodifiable(input);
   }

   /// Merges this with [other].
   ///
   /// For most fields, if both configurations have values set, [other]'s value
   /// takes precedence. However, certain fields are merged together instead.
   /// This is indicated in those fields' documentation.
   SuiteConfiguration merge(SuiteConfiguration other) {
     if (this == SuiteConfiguration.empty) return other;
     if (other == SuiteConfiguration.empty) return this;

     var config = SuiteConfiguration._(
         jsTrace: other._jsTrace ?? _jsTrace,
         runSkipped: other._runSkipped ?? _runSkipped,
         dart2jsArgs: dart2jsArgs.toList()..addAll(other.dart2jsArgs),
         precompiledPath: other.precompiledPath ?? precompiledPath,
         patterns: patterns.union(other.patterns),
         runtimes: other._runtimes ?? _runtimes,
         includeTags: includeTags.intersection(other.includeTags),
         excludeTags: excludeTags.union(other.excludeTags),
         tags: _mergeConfigMaps(tags, other.tags),
         onPlatform: _mergeConfigMaps(onPlatform, other.onPlatform),
         testRandomizeOrderingSeed:
             other.testRandomizeOrderingSeed ?? testRandomizeOrderingSeed,
         metadata: metadata.merge(other.metadata));
     return config._resolveTags();
   }

   /// Returns a copy of this configuration with the given fields updated.
   ///
   /// Note that unlike [merge], this has no merging behavior—the old value is
   /// always replaced by the new one.
   SuiteConfiguration change(
       {bool jsTrace,
       bool runSkipped,
       Iterable<String> dart2jsArgs,
       String precompiledPath,
       Iterable<Pattern> patterns,
       Iterable<RuntimeSelection> runtimes,
       BooleanSelector includeTags,
       BooleanSelector excludeTags,
       Map<BooleanSelector, SuiteConfiguration> tags,
       Map<PlatformSelector, SuiteConfiguration> onPlatform,
       int testRandomizeOrderingSeed,

       // Test-level configuration
       Timeout timeout,
       bool verboseTrace,
       bool chainStackTraces,
       bool skip,
       int retry,
       String skipReason,
       PlatformSelector testOn,
       Iterable<String> addTags}) {
     var config = SuiteConfiguration._(
         jsTrace: jsTrace ?? _jsTrace,
         runSkipped: runSkipped ?? _runSkipped,
         dart2jsArgs: dart2jsArgs?.toList() ?? this.dart2jsArgs,
         precompiledPath: precompiledPath ?? this.precompiledPath,
         patterns: patterns ?? this.patterns,
         runtimes: runtimes ?? _runtimes,
         includeTags: includeTags ?? this.includeTags,
         excludeTags: excludeTags ?? this.excludeTags,
         tags: tags ?? this.tags,
         onPlatform: onPlatform ?? this.onPlatform,
         testRandomizeOrderingSeed:
             testRandomizeOrderingSeed ?? testRandomizeOrderingSeed,
         metadata: _metadata.change(
             timeout: timeout,
             verboseTrace: verboseTrace,
             chainStackTraces: chainStackTraces,
             skip: skip,
             retry: retry,
             skipReason: skipReason,
             testOn: testOn,
             tags: addTags?.toSet()));
     return config._resolveTags();
   }

   /// Throws a [FormatException] if [this] refers to any undefined runtimes.
   void validateRuntimes(List<Runtime> allRuntimes) {
     var validVariables =
         allRuntimes.map((runtime) => runtime.identifier).toSet();
     _metadata.validatePlatformSelectors(validVariables);

     if (_runtimes != null) {
       for (var selection in _runtimes) {
         if (!allRuntimes
             .any((runtime) => runtime.identifier == selection.name)) {
           if (selection.span != null) {
             throw SourceSpanFormatException(
                 'Unknown platform "${selection.name}".', selection.span);
           } else {
             throw FormatException('Unknown platform "${selection.name}".');
           }
         }
       }
     }

     onPlatform.forEach((selector, config) {
       selector.validate(validVariables);
       config.validateRuntimes(allRuntimes);
     });
   }

   /// Returns a copy of [this] with all platform-specific configuration from
   /// [onPlatform] resolved.
   SuiteConfiguration forPlatform(SuitePlatform platform) {
     if (onPlatform.isEmpty) return this;

     var config = this;
     onPlatform.forEach((platformSelector, platformConfig) {
       if (!platformSelector.evaluate(platform)) return;
       config = config.merge(platformConfig);
     });
     return config.change(onPlatform: {});
   }

   /// Merges two maps whose values are [SuiteConfiguration]s.
   ///
   /// Any overlapping keys in the maps have their configurations merged in the
   /// returned map.
   Map<T, SuiteConfiguration> _mergeConfigMaps<T>(
           Map<T, SuiteConfiguration> map1, Map<T, SuiteConfiguration> map2) =>
       mergeMaps(map1, map2,
           value: (config1, config2) => config1.merge(config2));

   SuiteConfiguration _resolveTags() {
     // If there's no tag-specific configuration, or if none of it applies, just
     // return the configuration as-is.
     if (_metadata.tags.isEmpty || tags.isEmpty) return this;

     // Otherwise, resolve the tag-specific components.
     var newTags = Map<BooleanSelector, SuiteConfiguration>.from(tags);
     var merged = tags.keys.fold(empty, (SuiteConfiguration merged, selector) {
       if (!selector.evaluate(_metadata.tags.contains)) return merged;
       return merged.merge(newTags.remove(selector));
     });

     if (merged == empty) return this;
     return change(tags: newTags).merge(merged);
   }
 }
	// Copyright (c) 2016, 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:boolean_selector/boolean_selector.dart';
	import 'package:collection/collection.dart';
	import 'package:source_span/source_span.dart';

	import 'package:test_api/src/backend/metadata.dart'; // ignore: implementation_imports
	import 'package:test_api/src/backend/platform_selector.dart'; // ignore: implementation_imports
	import 'package:test_api/src/backend/suite_platform.dart'; // ignore: implementation_imports
	import 'package:test_api/src/backend/runtime.dart'; // ignore: implementation_imports
	import 'package:test_api/src/frontend/timeout.dart'; // ignore: implementation_imports

	import 'runtime_selection.dart';

	/// Suite-level configuration.
	///
	/// This tracks configuration that can differ from suite to suite.
	class SuiteConfiguration {
	/// Empty configuration with only default values.
	///
	/// Using this is slightly more efficient than manually constructing a new
	/// configuration with no arguments.
	static final empty = SuiteConfiguration._();

	/// Whether JavaScript stack traces should be left as-is or converted to
	/// Dart-like traces.
	bool get jsTrace => _jsTrace ?? false;
	final bool _jsTrace;

	/// Whether skipped tests should be run.
	bool get runSkipped => _runSkipped ?? false;
	final bool _runSkipped;

	/// The path to a mirror of this package containing HTML that points to
	/// precompiled JS.
	///
	/// This is used by the internal Google test runner so that test compilation
	/// can more effectively make use of Google's build tools.
	final String precompiledPath;

	/// Additional arguments to pass to dart2js.
	///
	/// Note that this if multiple suites run the same JavaScript on different
	/// runtimes, and they have different [dart2jsArgs], only one (undefined)
	/// suite's arguments will be used.
	final List<String> dart2jsArgs;

	/// The patterns to match against test names to decide which to run, or `null`
	/// if all tests should be run.
	///
	/// All patterns must match in order for a test to be run.
	final Set<Pattern> patterns;

	/// The set of runtimes on which to run tests.
	List<String> get runtimes => _runtimes == null
	? const ['vm']
	: List.unmodifiable(_runtimes.map((runtime) => runtime.name));
	final List<RuntimeSelection> _runtimes;

	/// Only run tests whose tags match this selector.
	///
	/// When [merge]d, this is intersected with the other configuration's included
	/// tags.
	final BooleanSelector includeTags;

	/// Do not run tests whose tags match this selector.
	///
	/// When [merge]d, this is unioned with the other configuration's
	/// excluded tags.
	final BooleanSelector excludeTags;

	/// Configuration for particular tags.
	///
	/// The keys are tag selectors, and the values are configurations for tests
	/// whose tags match those selectors.
	final Map<BooleanSelector, SuiteConfiguration> tags;

	/// Configuration for particular platforms.
	///
	/// The keys are platform selectors, and the values are configurations for
	/// those platforms. These configuration should only contain test-level
	/// configuration fields, but that isn't enforced.
	final Map<PlatformSelector, SuiteConfiguration> onPlatform;

	/// The seed with which to shuffle the test order.
	/// Default value is null if not provided and will not change the test order.
	/// The same seed will shuffle the tests in the same way every time.
	final int testRandomizeOrderingSeed;

	/// The global test metadata derived from this configuration.
	Metadata get metadata {
	if (tags.isEmpty && onPlatform.isEmpty) return _metadata;
	return _metadata.change(
	forTag: tags.map((key, config) => MapEntry(key, config.metadata)),
	onPlatform:
	onPlatform.map((key, config) => MapEntry(key, config.metadata)));
	}

	final Metadata _metadata;

	/// The set of tags that have been declared in any way in this configuration.
	Set<String> get knownTags {
	if (_knownTags != null) return _knownTags;

	var known = includeTags.variables.toSet()
	..addAll(excludeTags.variables)
	..addAll(_metadata.tags);

	for (var selector in tags.keys) {
	known.addAll(selector.variables);
	}

	for (var configuration in _children) {
	known.addAll(configuration.knownTags);
	}

	_knownTags = UnmodifiableSetView(known);
	return _knownTags;
	}

	Set<String> _knownTags;

	/// All child configurations of [this] that may be selected under various
	/// circumstances.
	Iterable<SuiteConfiguration> get _children sync* {
	yield* tags.values;
	yield* onPlatform.values;
	}

	factory SuiteConfiguration(
	{bool jsTrace,
	bool runSkipped,
	Iterable<String> dart2jsArgs,
	String precompiledPath,
	Iterable<Pattern> patterns,
	Iterable<RuntimeSelection> runtimes,
	BooleanSelector includeTags,
	BooleanSelector excludeTags,
	Map<BooleanSelector, SuiteConfiguration> tags,
	Map<PlatformSelector, SuiteConfiguration> onPlatform,
	int testRandomizeOrderingSeed,

	// Test-level configuration
	Timeout timeout,
	bool verboseTrace,
	bool chainStackTraces,
	bool skip,
	int retry,
	String skipReason,
	PlatformSelector testOn,
	Iterable<String> addTags}) {
	var config = SuiteConfiguration._(
	jsTrace: jsTrace,
	runSkipped: runSkipped,
	dart2jsArgs: dart2jsArgs,
	precompiledPath: precompiledPath,
	patterns: patterns,
	runtimes: runtimes,
	includeTags: includeTags,
	excludeTags: excludeTags,
	tags: tags,
	onPlatform: onPlatform,
	testRandomizeOrderingSeed: testRandomizeOrderingSeed,
	metadata: Metadata(
	timeout: timeout,
	verboseTrace: verboseTrace,
	chainStackTraces: chainStackTraces,
	skip: skip,
	retry: retry,
	skipReason: skipReason,
	testOn: testOn,
	tags: addTags));
	return config._resolveTags();
	}

	/// Creates new SuiteConfiguration.
	///
	/// Unlike [new SuiteConfiguration], this assumes [tags] is already
	/// resolved.
	SuiteConfiguration._(
	{bool jsTrace,
	bool runSkipped,
	Iterable<String> dart2jsArgs,
	this.precompiledPath,
	Iterable<Pattern> patterns,
	Iterable<RuntimeSelection> runtimes,
	BooleanSelector includeTags,
	BooleanSelector excludeTags,
	Map<BooleanSelector, SuiteConfiguration> tags,
	Map<PlatformSelector, SuiteConfiguration> onPlatform,
	int testRandomizeOrderingSeed,
	Metadata metadata})
	: _jsTrace = jsTrace,
	_runSkipped = runSkipped,
	dart2jsArgs = _list(dart2jsArgs) ?? const [],
	patterns = UnmodifiableSetView(patterns?.toSet() ?? {}),
	_runtimes = _list(runtimes),
	includeTags = includeTags ?? BooleanSelector.all,
	excludeTags = excludeTags ?? BooleanSelector.none,
	tags = _map(tags),
	onPlatform = _map(onPlatform),
	testRandomizeOrderingSeed = testRandomizeOrderingSeed,
	_metadata = metadata ?? Metadata.empty;

	/// Creates a new [SuiteConfiguration] that takes its configuration from
	/// [metadata].
	factory SuiteConfiguration.fromMetadata(Metadata metadata) =>
	SuiteConfiguration._(
	tags: metadata.forTag.map((key, child) =>
	MapEntry(key, SuiteConfiguration.fromMetadata(child))),
	onPlatform: metadata.onPlatform.map((key, child) =>
	MapEntry(key, SuiteConfiguration.fromMetadata(child))),
	metadata: metadata.change(forTag: {}, onPlatform: {}));

	/// Returns an unmodifiable copy of [input].
	///
	/// If [input] is `null` or empty, this returns `null`.
	static List<T> _list<T>(Iterable<T> input) {
	if (input == null) return null;
	var list = List<T>.unmodifiable(input);
	if (list.isEmpty) return null;
	return list;
	}

	/// Returns an unmodifiable copy of [input] or an empty unmodifiable map.
	static Map<K, V> _map<K, V>(Map<K, V> input) {
	if (input == null \|\| input.isEmpty) return const {};
	return Map.unmodifiable(input);
	}

	/// Merges this with [other].
	///
	/// For most fields, if both configurations have values set, [other]'s value
	/// takes precedence. However, certain fields are merged together instead.
	/// This is indicated in those fields' documentation.
	SuiteConfiguration merge(SuiteConfiguration other) {
	if (this == SuiteConfiguration.empty) return other;
	if (other == SuiteConfiguration.empty) return this;

	var config = SuiteConfiguration._(
	jsTrace: other._jsTrace ?? _jsTrace,
	runSkipped: other._runSkipped ?? _runSkipped,
	dart2jsArgs: dart2jsArgs.toList()..addAll(other.dart2jsArgs),
	precompiledPath: other.precompiledPath ?? precompiledPath,
	patterns: patterns.union(other.patterns),
	runtimes: other._runtimes ?? _runtimes,
	includeTags: includeTags.intersection(other.includeTags),
	excludeTags: excludeTags.union(other.excludeTags),
	tags: _mergeConfigMaps(tags, other.tags),
	onPlatform: _mergeConfigMaps(onPlatform, other.onPlatform),
	testRandomizeOrderingSeed:
	other.testRandomizeOrderingSeed ?? testRandomizeOrderingSeed,
	metadata: metadata.merge(other.metadata));
	return config._resolveTags();
	}

	/// Returns a copy of this configuration with the given fields updated.
	///
	/// Note that unlike [merge], this has no merging behavior—the old value is
	/// always replaced by the new one.
	SuiteConfiguration change(
	{bool jsTrace,
	bool runSkipped,
	Iterable<String> dart2jsArgs,
	String precompiledPath,
	Iterable<Pattern> patterns,
	Iterable<RuntimeSelection> runtimes,
	BooleanSelector includeTags,
	BooleanSelector excludeTags,
	Map<BooleanSelector, SuiteConfiguration> tags,
	Map<PlatformSelector, SuiteConfiguration> onPlatform,
	int testRandomizeOrderingSeed,

	// Test-level configuration
	Timeout timeout,
	bool verboseTrace,
	bool chainStackTraces,
	bool skip,
	int retry,
	String skipReason,
	PlatformSelector testOn,
	Iterable<String> addTags}) {
	var config = SuiteConfiguration._(
	jsTrace: jsTrace ?? _jsTrace,
	runSkipped: runSkipped ?? _runSkipped,
	dart2jsArgs: dart2jsArgs?.toList() ?? this.dart2jsArgs,
	precompiledPath: precompiledPath ?? this.precompiledPath,
	patterns: patterns ?? this.patterns,
	runtimes: runtimes ?? _runtimes,
	includeTags: includeTags ?? this.includeTags,
	excludeTags: excludeTags ?? this.excludeTags,
	tags: tags ?? this.tags,
	onPlatform: onPlatform ?? this.onPlatform,
	testRandomizeOrderingSeed:
	testRandomizeOrderingSeed ?? testRandomizeOrderingSeed,
	metadata: _metadata.change(
	timeout: timeout,
	verboseTrace: verboseTrace,
	chainStackTraces: chainStackTraces,
	skip: skip,
	retry: retry,
	skipReason: skipReason,
	testOn: testOn,
	tags: addTags?.toSet()));
	return config._resolveTags();
	}

	/// Throws a [FormatException] if [this] refers to any undefined runtimes.
	void validateRuntimes(List<Runtime> allRuntimes) {
	var validVariables =
	allRuntimes.map((runtime) => runtime.identifier).toSet();
	_metadata.validatePlatformSelectors(validVariables);

	if (_runtimes != null) {
	for (var selection in _runtimes) {
	if (!allRuntimes
	.any((runtime) => runtime.identifier == selection.name)) {
	if (selection.span != null) {
	throw SourceSpanFormatException(
	'Unknown platform "${selection.name}".', selection.span);
	} else {
	throw FormatException('Unknown platform "${selection.name}".');
	}
	}
	}
	}

	onPlatform.forEach((selector, config) {
	selector.validate(validVariables);
	config.validateRuntimes(allRuntimes);
	});
	}

	/// Returns a copy of [this] with all platform-specific configuration from
	/// [onPlatform] resolved.
	SuiteConfiguration forPlatform(SuitePlatform platform) {
	if (onPlatform.isEmpty) return this;

	var config = this;
	onPlatform.forEach((platformSelector, platformConfig) {
	if (!platformSelector.evaluate(platform)) return;
	config = config.merge(platformConfig);
	});
	return config.change(onPlatform: {});
	}

	/// Merges two maps whose values are [SuiteConfiguration]s.
	///
	/// Any overlapping keys in the maps have their configurations merged in the
	/// returned map.
	Map<T, SuiteConfiguration> _mergeConfigMaps<T>(
	Map<T, SuiteConfiguration> map1, Map<T, SuiteConfiguration> map2) =>
	mergeMaps(map1, map2,
	value: (config1, config2) => config1.merge(config2));

	SuiteConfiguration _resolveTags() {
	// If there's no tag-specific configuration, or if none of it applies, just
	// return the configuration as-is.
	if (_metadata.tags.isEmpty \|\| tags.isEmpty) return this;

	// Otherwise, resolve the tag-specific components.
	var newTags = Map<BooleanSelector, SuiteConfiguration>.from(tags);
	var merged = tags.keys.fold(empty, (SuiteConfiguration merged, selector) {
	if (!selector.evaluate(_metadata.tags.contains)) return merged;
	return merged.merge(newTags.remove(selector));
	});

	if (merged == empty) return this;
	return change(tags: newTags).merge(merged);
	}
	}