Add observatory_pub_packages snapshot to third_party

observatory_pub_packages/matcher/src/core_matchers.dart

+// Copyright (c) 2012, 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 matcher.core_matchers;
+
+import 'description.dart';
+import 'interfaces.dart';
+import 'util.dart';
+
+/// Returns a matcher that matches empty strings, maps or iterables
+/// (including collections) using the isEmpty property.
+const Matcher isEmpty = const _Empty();
+
+class _Empty extends Matcher {
+  const _Empty();
+  bool matches(item, Map matchState) {
+    return (item is Map || item is Iterable || item is String) && item.isEmpty;
+  }
+  Description describe(Description description) => description.add('empty');
+}
+
+/// Returns a matcher that matches non-empty strings, maps or iterables
+/// (including collections) using the isNotEmpty property.
+const Matcher isNotEmpty = const _NotEmpty();
+
+class _NotEmpty extends Matcher {
+  const _NotEmpty();
+
+  bool matches(item, Map matchState) {
+    return (item is Map || item is Iterable || item is String) &&
+      item.isNotEmpty;
+  }
+
+  Description describe(Description description) => description.add('non-empty');
+}
+
+/// A matcher that matches any null value.
+const Matcher isNull = const _IsNull();
+
+/// A matcher that matches any non-null value.
+const Matcher isNotNull = const _IsNotNull();
+
+class _IsNull extends Matcher {
+  const _IsNull();
+  bool matches(item, Map matchState) => item == null;
+  Description describe(Description description) => description.add('null');
+}
+
+class _IsNotNull extends Matcher {
+  const _IsNotNull();
+  bool matches(item, Map matchState) => item != null;
+  Description describe(Description description) => description.add('not null');
+}
+
+/// A matcher that matches the Boolean value true.
+const Matcher isTrue = const _IsTrue();
+
+/// A matcher that matches anything except the Boolean value true.
+const Matcher isFalse = const _IsFalse();
+
+class _IsTrue extends Matcher {
+  const _IsTrue();
+  bool matches(item, Map matchState) => item == true;
+  Description describe(Description description) => description.add('true');
+}
+
+class _IsFalse extends Matcher {
+  const _IsFalse();
+  bool matches(item, Map matchState) => item == false;
+  Description describe(Description description) => description.add('false');
+}
+
+/// A matcher that matches the numeric value NaN.
+const Matcher isNaN = const _IsNaN();
+
+/// A matcher that matches any non-NaN value.
+const Matcher isNotNaN = const _IsNotNaN();
+
+class _IsNaN extends Matcher {
+  const _IsNaN();
+  bool matches(item, Map matchState) => double.NAN.compareTo(item) == 0;
+  Description describe(Description description) => description.add('NaN');
+}
+
+class _IsNotNaN extends Matcher {
+  const _IsNotNaN();
+  bool matches(item, Map matchState) => double.NAN.compareTo(item) != 0;
+  Description describe(Description description) => description.add('not NaN');
+}
+
+/// Returns a matches that matches if the value is the same instance
+/// as [expected], using [identical].
+Matcher same(expected) => new _IsSameAs(expected);
+
+class _IsSameAs extends Matcher {
+  final _expected;
+  const _IsSameAs(this._expected);
+  bool matches(item, Map matchState) => identical(item, _expected);
+  // If all types were hashable we could show a hash here.
+  Description describe(Description description) =>
+      description.add('same instance as ').addDescriptionOf(_expected);
+}
+
+/// Returns a matcher that matches if the value is structurally equal to
+/// [expected].
+///
+/// If [expected] is a [Matcher], then it matches using that. Otherwise it tests
+/// for equality using `==` on the expected value.
+///
+/// For [Iterable]s and [Map]s, this will recursively match the elements. To
+/// handle cyclic structures a recursion depth [limit] can be provided. The
+/// default limit is 100. [Set]s will be compared order-independently.
+Matcher equals(expected, [int limit=100]) =>
+    expected is String
+        ? new _StringEqualsMatcher(expected)
+        : new _DeepMatcher(expected, limit);
+
+class _DeepMatcher extends Matcher {
+  final _expected;
+  final int _limit;
+  var count;
+
+  _DeepMatcher(this._expected, [int limit = 1000]) : this._limit = limit;
+
+  // Returns a pair (reason, location)
+  List _compareIterables(expected, actual, matcher, depth, location) {
+    if (actual is! Iterable) return ['is not Iterable', location];
+
+    var expectedIterator = expected.iterator;
+    var actualIterator = actual.iterator;
+    for (var index = 0; ; index++) {
+      // Advance in lockstep.
+      var expectedNext = expectedIterator.moveNext();
+      var actualNext = actualIterator.moveNext();
+
+      // If we reached the end of both, we succeeded.
+      if (!expectedNext && !actualNext) return null;
+
+      // Fail if their lengths are different.
+      var newLocation = '${location}[${index}]';
+      if (!expectedNext) return ['longer than expected', newLocation];
+      if (!actualNext) return ['shorter than expected', newLocation];
+
+      // Match the elements.
+      var rp = matcher(expectedIterator.current, actualIterator.current,
+          newLocation, depth);
+      if (rp != null) return rp;
+    }
+  }
+
+  List _compareSets(Set expected, actual, matcher, depth, location) {
+    if (actual is! Iterable) return ['is not Iterable', location];
+    actual = actual.toSet();
+
+    for (var expectedElement in expected) {
+      if (actual.every((actualElement) =>
+          matcher(expectedElement, actualElement, location, depth) != null)) {
+        return ['does not contain $expectedElement', location];
+      }
+    }
+
+    if (actual.length > expected.length) {
+      return ['larger than expected', location];
+    } else if (actual.length < expected.length) {
+      return ['smaller than expected', location];
+    } else {
+      return null;
+    }
+  }
+
+  List _recursiveMatch(expected, actual, String location, int depth) {
+    // If the expected value is a matcher, try to match it.
+    if (expected is Matcher) {
+      var matchState = {};
+      if (expected.matches(actual, matchState)) return null;
+
+      var description = new StringDescription();
+      expected.describe(description);
+      return ['does not match $description', location];
+    } else {
+      // Otherwise, test for equality.
+      try {
+        if (expected == actual) return null;
+      } catch (e, s) {
+        // TODO(gram): Add a test for this case.
+        return ['== threw "$e"', location];
+      }
+    }
+
+    if (depth > _limit) return ['recursion depth limit exceeded', location];
+
+    // If _limit is 1 we can only recurse one level into object.
+    if (depth == 0 || _limit > 1) {
+      if (expected is Set) {
+        return _compareSets(expected, actual, _recursiveMatch, depth + 1,
+            location);
+      } else if (expected is Iterable) {
+        return _compareIterables(expected, actual, _recursiveMatch, depth + 1,
+            location);
+      } else if (expected is Map) {
+        if (actual is! Map) return ['expected a map', location];
+
+        var err = (expected.length == actual.length) ? '' :
+                  'has different length and ';
+        for (var key in expected.keys) {
+          if (!actual.containsKey(key)) {
+            return ["${err}is missing map key '$key'", location];
+          }
+        }
+
+        for (var key in actual.keys) {
+          if (!expected.containsKey(key)) {
+            return ["${err}has extra map key '$key'", location];
+          }
+        }
+
+        for (var key in expected.keys) {
+          var rp = _recursiveMatch(expected[key], actual[key],
+              "${location}['${key}']", depth + 1);
+          if (rp != null) return rp;
+        }
+
+        return null;
+      }
+    }
+
+    var description = new StringDescription();
+
+    // If we have recursed, show the expected value too; if not, expect() will
+    // show it for us.
+    if (depth > 0) {
+      description.add('was ').
+          addDescriptionOf(actual).
+          add(' instead of ').
+          addDescriptionOf(expected);
+      return [description.toString(), location];
+    }
+
+    // We're not adding any value to the actual value.
+    return ["", location];
+  }
+
+  String _match(expected, actual, Map matchState) {
+    var rp = _recursiveMatch(expected, actual, '', 0);
+    if (rp == null) return null;
+    var reason;
+    if (rp[0].length > 0) {
+      if (rp[1].length > 0) {
+        reason = "${rp[0]} at location ${rp[1]}";
+      } else {
+        reason = rp[0];
+      }
+    } else {
+      reason = '';
+    }
+    // Cache the failure reason in the matchState.
+    addStateInfo(matchState, {'reason': reason});
+    return reason;
+  }
+
+  bool matches(item, Map matchState) =>
+      _match(_expected, item, matchState) == null;
+
+  Description describe(Description description) =>
+    description.addDescriptionOf(_expected);
+
+  Description describeMismatch(item, Description mismatchDescription,
+                               Map matchState, bool verbose) {
+    var reason = matchState['reason'];
+    // If we didn't get a good reason, that would normally be a
+    // simple 'is <value>' message. We only add that if the mismatch
+    // description is non empty (so we are supplementing the mismatch
+    // description).
+    if (reason.length == 0 && mismatchDescription.length > 0) {
+      mismatchDescription.add('is ').addDescriptionOf(item);
+    } else {
+      mismatchDescription.add(reason);
+    }
+    return mismatchDescription;
+  }
+}
+
+/// A special equality matcher for strings.
+class _StringEqualsMatcher extends Matcher {
+  final String _value;
+
+  _StringEqualsMatcher(this._value);
+
+  bool get showActualValue => true;
+
+  bool matches(item, Map matchState) => _value == item;
+
+  Description describe(Description description) =>
+      description.addDescriptionOf(_value);
+
+  Description describeMismatch(item, Description mismatchDescription,
+      Map matchState, bool verbose) {
+    if (item is! String) {
+      return mismatchDescription.addDescriptionOf(item).add('is not a string');
+    } else {
+      var buff = new StringBuffer();
+      buff.write('is different.');
+      var escapedItem = _escape(item);
+      var escapedValue = _escape(_value);
+      int minLength = escapedItem.length < escapedValue.length ?
+          escapedItem.length : escapedValue.length;
+      int start;
+      for (start = 0; start < minLength; start++) {
+        if (escapedValue.codeUnitAt(start) != escapedItem.codeUnitAt(start)) {
+          break;
+        }
+      }
+      if (start == minLength) {
+        if (escapedValue.length < escapedItem.length) {
+          buff.write(' Both strings start the same, but the given value also'
+              ' has the following trailing characters: ');
+          _writeTrailing(buff, escapedItem, escapedValue.length);
+        } else {
+          buff.write(' Both strings start the same, but the given value is'
+              ' missing the following trailing characters: ');
+          _writeTrailing(buff, escapedValue, escapedItem.length);
+        }
+      } else {
+        buff.write('\nExpected: ');
+        _writeLeading(buff, escapedValue, start);
+        _writeTrailing(buff, escapedValue, start);
+        buff.write('\n  Actual: ');
+        _writeLeading(buff, escapedItem, start);
+        _writeTrailing(buff, escapedItem, start);
+        buff.write('\n          ');
+        for (int i = (start > 10 ? 14 : start); i > 0; i--) buff.write(' ');
+        buff.write('^\n Differ at offset $start');
+      }
+
+      return mismatchDescription.replace(buff.toString());
+    }
+  }
+
+  static String _escape(String s) =>
+      s.replaceAll('\n', '\\n').replaceAll('\r', '\\r').replaceAll('\t', '\\t');
+
+  static void _writeLeading(StringBuffer buff, String s, int start) {
+    if (start > 10) {
+      buff.write('... ');
+      buff.write(s.substring(start - 10, start));
+    } else {
+      buff.write(s.substring(0, start));
+    }
+  }
+
+  static void _writeTrailing(StringBuffer buff, String s, int start) {
+    if (start + 10 > s.length) {
+      buff.write(s.substring(start));
+    } else {
+      buff.write(s.substring(start, start + 10));
+      buff.write(' ...');
+    }
+  }
+}
+
+/// A matcher that matches any value.
+const Matcher anything = const _IsAnything();
+
+class _IsAnything extends Matcher {
+  const _IsAnything();
+  bool matches(item, Map matchState) => true;
+  Description describe(Description description) => description.add('anything');
+}
+
+/// Returns a matcher that matches if an object is an instance
+/// of [type] (or a subtype).
+///
+/// As types are not first class objects in Dart we can only
+/// approximate this test by using a generic wrapper class.
+///
+/// For example, to test whether 'bar' is an instance of type
+/// 'Foo', we would write:
+///
+///     expect(bar, new isInstanceOf<Foo>());
+///
+/// To get better error message, supply a name when creating the
+/// Type wrapper; e.g.:
+///
+///     expect(bar, new isInstanceOf<Foo>('Foo'));
+///
+/// Note that this does not currently work in dart2js; it will
+/// match any type, and isNot(new isInstanceof<T>()) will always
+/// fail. This is because dart2js currently ignores template type
+/// parameters.
+class isInstanceOf<T> extends Matcher {
+  final String _name;
+  const isInstanceOf([name = 'specified type']) : this._name = name;
+  bool matches(obj, Map matchState) => obj is T;
+  // The description here is lame :-(
+  Description describe(Description description) =>
+      description.add('an instance of ${_name}');
+}
+
+/// A matcher that matches a function call against no exception.
+///
+/// The function will be called once. Any exceptions will be silently swallowed.
+/// The value passed to expect() should be a reference to the function.
+/// Note that the function cannot take arguments; to handle this
+/// a wrapper will have to be created.
+const Matcher returnsNormally = const _ReturnsNormally();
+
+class _ReturnsNormally extends Matcher {
+  const _ReturnsNormally();
+
+  bool matches(f, Map matchState) {
+    try {
+      f();
+      return true;
+    } catch (e, s) {
+      addStateInfo(matchState, {'exception': e, 'stack': s});
+      return false;
+    }
+  }
+
+  Description describe(Description description) =>
+      description.add("return normally");
+
+  Description describeMismatch(item, Description mismatchDescription,
+                               Map matchState,
+                               bool verbose) {
+    mismatchDescription.add('threw ').addDescriptionOf(matchState['exception']);
+    if (verbose) {
+      mismatchDescription.add(' at ').add(matchState['stack'].toString());
+    }
+    return mismatchDescription;
+  }
+}
+
+/*
+ * Matchers for different exception types. Ideally we should just be able to
+ * use something like:
+ *
+ * final Matcher throwsException =
+ *     const _Throws(const isInstanceOf<Exception>());
+ *
+ * Unfortunately instanceOf is not working with dart2js.
+ *
+ * Alternatively, if static functions could be used in const expressions,
+ * we could use:
+ *
+ * bool _isException(x) => x is Exception;
+ * final Matcher isException = const _Predicate(_isException, "Exception");
+ * final Matcher throwsException = const _Throws(isException);
+ *
+ * But currently using static functions in const expressions is not supported.
+ * For now the only solution for all platforms seems to be separate classes
+ * for each exception type.
+ */
+
+abstract class TypeMatcher extends Matcher {
+  final String _name;
+  const TypeMatcher(this._name);
+  Description describe(Description description) => description.add(_name);
+}
+
+/// A matcher for Map types.
+const Matcher isMap = const _IsMap();
+
+class _IsMap extends TypeMatcher {
+  const _IsMap() : super("Map");
+  bool matches(item, Map matchState) => item is Map;
+}
+
+/// A matcher for List types.
+const Matcher isList = const _IsList();
+
+class _IsList extends TypeMatcher {
+  const _IsList() : super("List");
+  bool matches(item, Map matchState) => item is List;
+}
+
+/// Returns a matcher that matches if an object has a length property
+/// that matches [matcher].
+Matcher hasLength(matcher) => new _HasLength(wrapMatcher(matcher));
+
+class _HasLength extends Matcher {
+  final Matcher _matcher;
+  const _HasLength([Matcher matcher = null]) : this._matcher = matcher;
+
+  bool matches(item, Map matchState) {
+    try {
+      // This is harmless code that will throw if no length property
+      // but subtle enough that an optimizer shouldn't strip it out.
+      if (item.length * item.length >= 0) {
+        return _matcher.matches(item.length, matchState);
+      }
+    } catch (e) {}
+    return false;
+  }
+
+  Description describe(Description description) =>
+    description.add('an object with length of ').
+        addDescriptionOf(_matcher);
+
+  Description describeMismatch(item, Description mismatchDescription,
+                               Map matchState, bool verbose) {
+    try {
+      // We want to generate a different description if there is no length
+      // property; we use the same trick as in matches().
+      if (item.length * item.length >= 0) {
+        return mismatchDescription.add('has length of ').
+            addDescriptionOf(item.length);
+      }
+    } catch (e) {}
+    return mismatchDescription.add('has no length property');
+  }
+}
+
+/// Returns a matcher that matches if the match argument contains the expected
+/// value.
+///
+/// For [String]s this means substring matching;
+/// for [Map]s it means the map has the key, and for [Iterable]s
+/// it means the iterable has a matching element. In the case of iterables,
+/// [expected] can itself be a matcher.
+Matcher contains(expected) => new _Contains(expected);
+
+class _Contains extends Matcher {
+  final _expected;
+
+  const _Contains(this._expected);
+
+  bool matches(item, Map matchState) {
+    if (item is String) {
+      return item.indexOf(_expected) >= 0;
+    } else if (item is Iterable) {
+      if (_expected is Matcher) {
+        return item.any((e) => _expected.matches(e, matchState));
+      } else {
+        return item.contains(_expected);
+      }
+    } else if (item is Map) {
+      return item.containsKey(_expected);
+    }
+    return false;
+  }
+
+  Description describe(Description description) =>
+      description.add('contains ').addDescriptionOf(_expected);
+
+  Description describeMismatch(item, Description mismatchDescription,
+                               Map matchState, bool verbose) {
+    if (item is String || item is Iterable || item is Map) {
+      return super.describeMismatch(item, mismatchDescription, matchState,
+          verbose);
+    } else {
+      return mismatchDescription.add('is not a string, map or iterable');
+    }
+  }
+}
+
+/// Returns a matcher that matches if the match argument is in
+/// the expected value. This is the converse of [contains].
+Matcher isIn(expected) => new _In(expected);
+
+class _In extends Matcher {
+  final _expected;
+
+  const _In(this._expected);
+
+  bool matches(item, Map matchState) {
+    if (_expected is String) {
+      return _expected.indexOf(item) >= 0;
+    } else if (_expected is Iterable) {
+      return _expected.any((e) => e == item);
+    } else if (_expected is Map) {
+      return _expected.containsKey(item);
+    }
+    return false;
+  }
+
+  Description describe(Description description) =>
+      description.add('is in ').addDescriptionOf(_expected);
+}
+
+/// Returns a matcher that uses an arbitrary function that returns
+/// true or false for the actual value.
+///
+/// For example:
+///
+///     expect(v, predicate((x) => ((x % 2) == 0), "is even"))
+Matcher predicate(bool f(value), [String description = 'satisfies function']) =>
+    new _Predicate(f, description);
+
+typedef bool _PredicateFunction(value);
+
+class _Predicate extends Matcher {
+  final _PredicateFunction _matcher;
+  final String _description;
+
+  const _Predicate(this._matcher, this._description);
+
+  bool matches(item, Map matchState) => _matcher(item);
+
+  Description describe(Description description) =>
+      description.add(_description);
+}
+
+/// A useful utility class for implementing other matchers through inheritance.
+/// Derived classes should call the base constructor with a feature name and
+/// description, and an instance matcher, and should implement the
+/// [featureValueOf] abstract method.
+///
+/// The feature description will typically describe the item and the feature,
+/// while the feature name will just name the feature. For example, we may
+/// have a Widget class where each Widget has a price; we could make a
+/// [CustomMatcher] that can make assertions about prices with:
+///
+///     class HasPrice extends CustomMatcher {
+///       const HasPrice(matcher) :
+///           super("Widget with price that is", "price", matcher);
+///       featureValueOf(actual) => actual.price;
+///     }
+///
+/// and then use this for example like:
+///
+///      expect(inventoryItem, new HasPrice(greaterThan(0)));
+class CustomMatcher extends Matcher {
+  final String _featureDescription;
+  final String _featureName;
+  final Matcher _matcher;
+
+  CustomMatcher(this._featureDescription, this._featureName, matcher)
+      : this._matcher = wrapMatcher(matcher);
+
+  /// Override this to extract the interesting feature.
+  featureValueOf(actual) => actual;
+
+  bool matches(item, Map matchState) {
+    var f = featureValueOf(item);
+    if (_matcher.matches(f, matchState)) return true;
+    addStateInfo(matchState, {'feature': f});
+    return false;
+  }
+
+  Description describe(Description description) =>
+      description.add(_featureDescription).add(' ').addDescriptionOf(_matcher);
+
+  Description describeMismatch(item, Description mismatchDescription,
+                               Map matchState, bool verbose) {
+    mismatchDescription.add('has ').add(_featureName).add(' with value ').
+        addDescriptionOf(matchState['feature']);
+    var innerDescription = new StringDescription();
+    _matcher.describeMismatch(matchState['feature'], innerDescription,
+        matchState['state'], verbose);
+    if (innerDescription.length > 0) {
+      mismatchDescription.add(' which ').add(innerDescription.toString());
+    }
+    return mismatchDescription;
+  }
+}