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packages/quiver/test/testing/equality/equality_test.dart

+// Copyright 2014 Google Inc. All Rights Reserved.
+//
+// Licensed under the Apache License, Version 2.0 (the 'License');
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an 'AS IS' BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+library quiver.testing.util.equalstester;
+
+import 'package:quiver/testing/equality.dart';
+import 'package:test/test.dart';
+
+main() {
+  group('expectEquals', () {
+    _ValidTestObject reference;
+    _ValidTestObject equalObject1;
+    _ValidTestObject equalObject2;
+    _ValidTestObject notEqualObject1;
+
+    setUp(() {
+      reference = new _ValidTestObject(1, 2);
+      equalObject1 = new _ValidTestObject(1, 2);
+      equalObject2 = new _ValidTestObject(1, 2);
+      notEqualObject1 = new _ValidTestObject(0, 2);
+    });
+
+    test('Test null reference yields error', () {
+      try {
+        expect(null, areEqualityGroups);
+        fail('Should fail with null reference');
+      } catch (e) {
+        expect(e.toString(), contains('Equality Group must not be null'));
+      }
+    });
+
+    test('Test null group name yields error', () {
+      try {
+        expect({'null': [reference], null: [reference]}, areEqualityGroups);
+        fail('Should fail with null group name');
+      } catch (e) {
+        expect(e.toString(), contains('Group name must not be null'));
+      }
+    });
+
+    test('Test null group yields error', () {
+      try {
+        expect({'bad group': null}, areEqualityGroups);
+        fail('Should fail with null group');
+      } catch (e) {
+        expect(e.toString(), contains('Group must not be null'));
+      }
+    });
+
+    test('Test after adding multiple instances at once with a null', () {
+      try {
+        expect(
+            {'bad group': [reference, equalObject1, null]}, areEqualityGroups);
+        fail('Should fail with null group');
+      } catch (e) {
+        expect(e.toString(), contains("$reference [group 'bad group', item 1]"
+            " must be equal to null [group 'bad group', item 3]"));
+      }
+    });
+
+    test('Test adding non-equal objects only in single group.', () {
+      try {
+        expect(
+            {'not equal': [equalObject1, notEqualObject1]}, areEqualityGroups);
+        fail("Should get not equal to equal object error");
+      } catch (e) {
+        expect(e.toString(), contains("$equalObject1 [group 'not equal', item"
+            " 1] must be equal to $notEqualObject1 [group 'not equal'"
+            ", item 2]"));
+      }
+    });
+
+    test('Test with no equals or not equals objects. This checks'
+        ' proper handling of null, incompatible class and reflexive tests', () {
+      expect({'single object': [reference]}, areEqualityGroups);
+    });
+
+    test('Test after populating equal objects. This checks proper'
+        ' handling of equality and verifies hashCode for valid objects', () {
+      expect({
+        'all equal': [reference, equalObject1, equalObject2]
+      }, areEqualityGroups);
+    });
+
+    test('Test proper handling of case where an object is not equal to itself',
+        () {
+      Object obj = new _NonReflexiveObject();
+      try {
+        expect({'non-reflexive': [obj]}, areEqualityGroups);
+        fail("Should get non-reflexive error");
+      } catch (e) {
+        expect(e.toString(), contains("$obj must be equal to itself"));
+      }
+    });
+
+    test('Test proper handling of case where hashcode is not idempotent', () {
+      Object obj = new _InconsistentHashCodeObject(1, 2);
+      try {
+        expect({'non-reflexive': [obj]}, areEqualityGroups);
+        fail("Should get non-reflexive error");
+      } catch (e) {
+        expect(e.toString(), contains(
+            "the implementation of hashCode of $obj must be idempotent"));
+      }
+    });
+
+    test('Test proper handling where an object incorrectly tests for an '
+        'incompatible class', () {
+      Object obj = new _InvalidEqualsIncompatibleClassObject();
+      try {
+        expect({'equals method broken': [obj]}, areEqualityGroups);
+        fail("Should get equal to incompatible class error");
+      } catch (e) {
+        expect(e.toString(), contains("$obj must not be equal to an "
+            "arbitrary object of another class"));
+      }
+    });
+
+    test('Test proper handling where an object is not equal to one the user '
+        'has said should be equal', () {
+      try {
+        expect({'non-equal': [reference, notEqualObject1]}, areEqualityGroups);
+        fail("Should get not equal to equal object error");
+      } catch (e) {
+        expect(
+            e.toString(), contains("$reference [group 'non-equal', item 1]"));
+        expect(e.toString(),
+            contains("$notEqualObject1 [group 'non-equal', item 2]"));
+      }
+    });
+
+    test('Test for an invalid hashCode method, i.e., one that returns '
+        'different value for objects that are equal according to the equals '
+        'method', () {
+      Object a = new _InvalidHashCodeObject(1, 2);
+      Object b = new _InvalidHashCodeObject(1, 2);
+      try {
+        expect({'invalid hashcode': [a, b]}, areEqualityGroups);
+        fail("Should get invalid hashCode error");
+      } catch (e) {
+        expect(e.toString(), contains("the hashCode (${a.hashCode}) of $a"
+            " [group 'invalid hashcode', item 1] must be equal to the"
+            " hashCode (${b.hashCode}) of $b"));
+      }
+    });
+
+    test('Symmetry Broken', () {
+      try {
+        expect({
+          'broken symmetry': [named('foo')..addPeers(['bar']), named('bar')]
+        }, areEqualityGroups);
+        fail("should fail because symmetry is broken");
+      } catch (e) {
+        expect(e.toString(), contains("bar [group 'broken symmetry', item 2] "
+            "must be equal to foo [group 'broken symmetry', item 1]"));
+      }
+    });
+
+    test('Transitivity Broken In EqualityGroup', () {
+      try {
+        expect({
+          'transitivity broken': [
+            named('foo')..addPeers(['bar', 'baz']),
+            named('bar')..addPeers(['foo']),
+            named('baz')..addPeers(['foo'])
+          ]
+        }, areEqualityGroups);
+        fail("should fail because transitivity is broken");
+      } catch (e) {
+        expect(e.toString(), contains("bar [group 'transitivity broken', "
+            "item 2] must be equal to baz [group 'transitivity "
+            "broken', item 3]"));
+      }
+    });
+
+    test('Unequal Objects In EqualityGroup', () {
+      try {
+        expect({
+          'unequal objects': [named('foo'), named('bar')]
+        }, areEqualityGroups);
+        fail('should fail because of unequal objects in the same equality '
+            'group');
+      } catch (e) {
+        expect(e.toString(), contains("foo [group 'unequal objects', item 1] "
+            "must be equal to bar [group 'unequal objects', item 2]"));
+      }
+    });
+
+    test('Transitivity Broken Across EqualityGroups', () {
+      try {
+        expect({
+          'transitivity one': [
+            named('foo')..addPeers(['bar']),
+            named('bar')..addPeers(['foo', 'x'])
+          ],
+          'transitivity two': [
+            named('baz')..addPeers(['x']),
+            named('x')..addPeers(['baz', 'bar'])
+          ]
+        }, areEqualityGroups);
+        fail('should fail because transitivity is broken');
+      } catch (e) {
+        expect(e.toString(), contains("bar [group 'transitivity one', item 2]"
+            " must not be equal to x [group 'transitivity two',"
+            " item 2]"));
+      }
+    });
+
+    test('EqualityGroups', () {
+      expect({
+        'valid groups one': [
+          named('foo').addPeers(['bar']),
+          named('bar').addPeers(['foo'])
+        ],
+        'valid groups two': [named('baz'), named('baz')]
+      }, areEqualityGroups);
+    });
+  });
+}
+
+/// Test class that violates reflexitivity.  It is not equal to itself.
+class _NonReflexiveObject {
+  @override
+  bool operator ==(Object o) => false;
+
+  @override
+  int get hashCode => super.hashCode;
+}
+
+/**
+ * Test class with valid equals and hashCode methods. Testers created
+ * with instances of this class should always pass.
+ */
+class _ValidTestObject {
+  int aspect1;
+  int aspect2;
+
+  _ValidTestObject(this.aspect1, this.aspect2);
+
+  @override
+  bool operator ==(Object o) {
+    if (!(o is _ValidTestObject)) {
+      return false;
+    }
+    _ValidTestObject other = o as _ValidTestObject;
+    if (aspect1 != other.aspect1) {
+      return false;
+    }
+    if (aspect2 != other.aspect2) {
+      return false;
+    }
+    return true;
+  }
+
+  @override
+  int get hashCode {
+    int result = 17;
+    result = 37 * result + aspect1;
+    result = 37 * result + aspect2;
+    return result;
+  }
+}
+
+///Test class that returns true even if the test object is of the wrong class.
+class _InvalidEqualsIncompatibleClassObject {
+  @override
+  bool operator ==(Object o) {
+    return true;
+  }
+
+  @override
+  int get hashCode => 0;
+}
+
+/// Test class with inconsistent hashCode method.
+class _InconsistentHashCodeObject {
+  int _aspect1;
+  int _aspect2;
+  int _hashCode = 0;
+
+  _InconsistentHashCodeObject(this._aspect1, this._aspect2);
+
+  @override
+  int get hashCode => _hashCode++;
+
+  @override
+  bool operator ==(Object o) {
+    if (!(o is _InconsistentHashCodeObject)) {
+      return false;
+    }
+    _InconsistentHashCodeObject other = o as _InconsistentHashCodeObject;
+    if (_aspect1 != other._aspect1) return false;
+    if (_aspect2 != other._aspect2) return false;
+    return true;
+  }
+}
+
+/// Test class with invalid hashCode method.
+class _InvalidHashCodeObject {
+  static int hashCodeSource = 0;
+  int _aspect1;
+  int _aspect2;
+  int _hashCode = hashCodeSource++;
+
+  _InvalidHashCodeObject(this._aspect1, this._aspect2);
+
+  @override
+  int get hashCode => _hashCode;
+
+  @override
+  bool operator ==(Object o) {
+    if (!(o is _InvalidHashCodeObject)) {
+      return false;
+    }
+    _InvalidHashCodeObject other = o as _InvalidHashCodeObject;
+    if (_aspect1 != other._aspect1) return false;
+    if (_aspect2 != other._aspect2) return false;
+    return true;
+  }
+}
+
+_NamedObject named(String name) => new _NamedObject(name);
+
+class _NamedObject {
+  final Set<String> peerNames = new Set();
+  final String name;
+
+  _NamedObject(this.name);
+
+  void addPeers(List<String> names) {
+    peerNames.addAll(names);
+  }
+
+  @override
+  bool operator ==(Object obj) {
+    if (obj is _NamedObject) {
+      _NamedObject that = obj;
+      return name == that.name || peerNames.contains(that.name);
+    }
+    return false;
+  }
+
+  @override
+  int get hashCode => 0;
+
+  @override String toString() => name;
+}