Make toEqual matcher report the difference between objects

- Mismatches deep within object/array structures are pinpointed with a JsonPath-like syntax.

spec/core/PrettyPrintSpec.js

@@ -99,6 +99,11 @@ describe("jasmineUnderTest.pp", function () {
     }, bar: [1, 2, 3]})).toEqual("Object({ foo: Function, bar: [ 1, 2, 3 ] })");
   });
 
+  it("should print 'null' as the constructor of an object with its own constructor property", function() {
+    expect(jasmineUnderTest.pp({constructor: function() {}})).toEqual("null({ constructor: Function })");
+    expect(jasmineUnderTest.pp({constructor: 'foo'})).toEqual("null({ constructor: 'foo' })");
+  });
+
   it("should not include inherited properties when stringifying an object", function() {
     var SomeClass = function SomeClass() {};
     SomeClass.prototype.foo = "inherited foo";
@@ -164,7 +169,6 @@ describe("jasmineUnderTest.pp", function () {
     }
   });
 
-
   it('should not do HTML escaping of strings', function() {
     expect(jasmineUnderTest.pp('some <b>html string</b> &', false)).toEqual('\'some <b>html string</b> &\'');
   });

spec/core/UtilSpec.js

@@ -63,4 +63,37 @@ describe("jasmineUnderTest.util", function() {
       expect(actual).toEqual(expected);
     });
   });
+
+  describe("objectDifference", function() {
+    it("given two objects A and B, returns the properties in A not present in B", function() {
+      var a = {
+        foo: 3,
+        bar: 4,
+        baz: 5
+      };
+
+      var b = {
+        bar: 6,
+        quux: 7
+      };
+
+      expect(jasmineUnderTest.util.objectDifference(a, b)).toEqual({foo: 3, baz: 5})
+    });
+
+    it("only looks at own properties of both objects", function() {
+      function Foo() {}
+
+      Foo.prototype.x = 1;
+      Foo.prototype.y = 2;
+
+      var a = new Foo();
+      a.x = 1;
+
+      var b = new Foo();
+      b.y = 2;
+
+      expect(jasmineUnderTest.util.objectDifference(a, b)).toEqual({x: 1});
+      expect(jasmineUnderTest.util.objectDifference(b, a)).toEqual({y: 2});
+    })
+  })
 });

spec/core/integration/CustomMatchersSpec.js

@@ -79,6 +79,30 @@ describe("Custom Matchers (Integration)", function() {
     env.execute();
   });
 
+  it("displays an appropriate failure message if a custom equality matcher fails", function(done) {
+    env.it("spec using custom equality matcher", function() {
+      var customEqualityFn = function(a, b) {
+        // "foo" is not equal to anything
+        if (a === 'foo' || b === 'foo') {
+          return false;
+        }
+      };
+
+      env.addCustomEqualityTester(customEqualityFn);
+      env.expect({foo: 'foo'}).toEqual({foo: 'foo'});
+    });
+
+    var specExpectations = function(result) {
+      expect(result.status).toEqual('failed');
+      expect(result.failedExpectations[0].message).toEqual(
+        "Expected $.foo = 'foo' to equal 'foo'."
+      );
+    };
+
+    env.addReporter({ specDone: specExpectations, jasmineDone: done });
+    env.execute();
+  });
+
   it("uses the negative compare function for a negative comparison, if provided", function(done) {
     env.it("spec with custom negative comparison matcher", function() {
       env.addMatchers({

spec/core/matchers/DiffBuilderSpec.js

@@ -0,0 +1,47 @@
+describe("DiffBuilder", function() {
+  it("records the actual and expected objects", function() {
+    var diffBuilder = jasmineUnderTest.DiffBuilder();
+    diffBuilder.record({x: 'actual'}, {x: 'expected'});
+
+    expect(diffBuilder.getMessage()).toEqual("Expected Object({ x: 'actual' }) to equal Object({ x: 'expected' }).");
+  });
+
+  it("prints the path at which the difference was found", function() {
+    var diffBuilder = jasmineUnderTest.DiffBuilder();
+
+    diffBuilder.withPath('foo', function() {
+      diffBuilder.record({x: 'actual'}, {x: 'expected'});
+    });
+
+    expect(diffBuilder.getMessage()).toEqual("Expected $.foo = Object({ x: 'actual' }) to equal Object({ x: 'expected' }).");
+  });
+
+  it("prints multiple messages, separated by newlines", function() {
+    var diffBuilder = jasmineUnderTest.DiffBuilder();
+
+    diffBuilder.withPath('foo', function() {
+      diffBuilder.record(1, 2);
+    });
+
+    var message =
+      "Expected $.foo = 1 to equal 2.\n" +
+      "Expected 3 to equal 4.";
+
+    diffBuilder.record(3, 4);
+    expect(diffBuilder.getMessage()).toEqual(message);
+  });
+
+  it("allows customization of the message", function() {
+    var diffBuilder = jasmineUnderTest.DiffBuilder();
+
+    function darthVaderFormatter(actual, expected, path) {
+      return "I find your lack of " + expected + " disturbing. (was " + actual + ", at " + path + ")"
+    }
+
+    diffBuilder.withPath('x', function() {
+      diffBuilder.record('bar', 'foo', darthVaderFormatter);
+    });
+
+    expect(diffBuilder.getMessage()).toEqual("I find your lack of foo disturbing. (was bar, at $.x)");
+  });
+});

spec/core/matchers/NullDiffBuilderSpec.js

@@ -0,0 +1,13 @@
+describe('NullDiffBuilder', function() {
+  it('responds to withPath() by calling the passed function', function() {
+    var spy = jasmine.createSpy('callback');
+    jasmineUnderTest.NullDiffBuilder().withPath('does not matter', spy);
+    expect(spy).toHaveBeenCalled();
+  });
+
+  it('responds to record()', function() {
+    expect(function() {
+      jasmineUnderTest.NullDiffBuilder().record('does not matter');
+    }).not.toThrow();
+  })
+});

spec/core/matchers/ObjectPathSpec.js

@@ -0,0 +1,43 @@
+describe('ObjectPath', function() {
+  var ObjectPath = jasmineUnderTest.ObjectPath;
+
+  it('represents the path to a node in an object tree', function() {
+    expect(new ObjectPath(['foo', 'bar']).toString()).toEqual('$.foo.bar');
+  });
+
+  it('has a depth', function() {
+    expect(new ObjectPath().depth()).toEqual(0);
+    expect(new ObjectPath(['foo']).depth()).toEqual(1);
+  });
+
+  it('renders numbers as array access', function() {
+    expect(new ObjectPath(['foo', 0]).toString()).toEqual('$.foo[0]');
+  });
+
+  it('renders properties that are valid identifiers with dot notation', function() {
+    expect(new ObjectPath(['foo123']).toString()).toEqual('$.foo123');
+    expect(new ObjectPath(['x_y']).toString()).toEqual('$.x_y');
+    expect(new ObjectPath(['A$B']).toString()).toEqual('$.A$B');
+  });
+
+  it('renders properties with non-identifier-safe characters with square bracket notation', function() {
+    expect(new ObjectPath(['a b c']).toString()).toEqual("$['a b c']");
+    expect(new ObjectPath(['1hello']).toString()).toEqual("$['1hello']");
+  });
+
+  it('renders as the empty string when empty', function() {
+    expect(new ObjectPath().toString()).toEqual('');
+  });
+
+  it('stringifies properties that are not strings or numbers', function() {
+    expect(new ObjectPath([{}]).toString()).toEqual("$['[object Object]']");
+  });
+
+  it('can be created based on another path', function() {
+    var root = new ObjectPath();
+    var path = root.add('foo');
+
+    expect(path.toString()).toEqual('$.foo');
+    expect(root.toString()).toEqual('');
+  })
+});

spec/core/matchers/matchersUtilSpec.js

@@ -61,10 +61,14 @@ describe("matchersUtil", function() {
       expect(jasmineUnderTest.matchersUtil.equals(foo, [undefined])).toBe(true);
     });
 
-    it("fails for Arrays that are not equivalent", function() {
+    it("fails for Arrays that have different lengths", function() {
       expect(jasmineUnderTest.matchersUtil.equals([1, 2], [1, 2, 3])).toBe(false);
     });
 
+    it("fails for Arrays that have different elements", function() {
+      expect(jasmineUnderTest.matchersUtil.equals([1, 2, 3], [1, 5, 3])).toBe(false);
+    });
+
     it("fails for Arrays whose contents are equivalent, but have differing properties", function() {
       var one = [1,2,3],
           two = [1,2,3];
@@ -136,6 +140,13 @@ describe("matchersUtil", function() {
       expect(jasmineUnderTest.matchersUtil.equals(actual, expected)).toBe(false);
     });
 
+    it("fails for Objects that have the same number of keys, but different keys/values", function () {
+      var expected = { a: undefined },
+        actual = { b: 1 };
+
+      expect(jasmineUnderTest.matchersUtil.equals(actual, expected)).toBe(false);
+    })
+
     it("fails when comparing an empty object to an empty array (issue #114)", function() {
       var emptyObject = {},
         emptyArray = [];

spec/core/matchers/toEqualSpec.js

@@ -1,20 +1,39 @@
 describe("toEqual", function() {
+  "use strict";
+
+  function compareEquals(actual, expected) {
+    var util = jasmineUnderTest.matchersUtil,
+      matcher = jasmineUnderTest.matchers.toEqual(util);
+
+    var result = matcher.compare(actual, expected);
+
+    return result;
+  }
+
   it("delegates to equals function", function() {
     var util = {
-        equals: jasmine.createSpy('delegated-equals').and.returnValue(true)
+        equals: jasmine.createSpy('delegated-equals').and.returnValue(true),
+        buildFailureMessage: function() {
+          return 'does not matter'
+        },
+        DiffBuilder: jasmineUnderTest.matchersUtil.DiffBuilder
       },
       matcher = jasmineUnderTest.matchers.toEqual(util),
       result;
 
     result = matcher.compare(1, 1);
 
-    expect(util.equals).toHaveBeenCalledWith(1, 1, []);
+    expect(util.equals).toHaveBeenCalledWith(1, 1, [], jasmine.anything());
     expect(result.pass).toBe(true);
   });
 
   it("delegates custom equality testers, if present", function() {
     var util = {
-        equals: jasmine.createSpy('delegated-equals').and.returnValue(true)
+        equals: jasmine.createSpy('delegated-equals').and.returnValue(true),
+        buildFailureMessage: function() {
+          return 'does not matter'
+        },
+        DiffBuilder: jasmineUnderTest.matchersUtil.DiffBuilder
       },
       customEqualityTesters = ['a', 'b'],
       matcher = jasmineUnderTest.matchers.toEqual(util, customEqualityTesters),
@@ -22,7 +41,457 @@ describe("toEqual", function() {
 
     result = matcher.compare(1, 1);
 
-    expect(util.equals).toHaveBeenCalledWith(1, 1, ['a', 'b']);
+    expect(util.equals).toHaveBeenCalledWith(1, 1, ['a', 'b'], jasmine.anything());
     expect(result.pass).toBe(true);
   });
+
+  it("reports the difference between objects that are not equal", function() {
+    var actual = {x: 1, y: 3},
+      expected = {x: 2, y: 3},
+      message = "Expected $.x = 1 to equal 2.";
+
+    expect(compareEquals(actual, expected).message).toEqual(message);
+  });
+
+  it("reports the difference between nested objects that are not equal", function() {
+    var actual = {x: {y: 1}},
+      expected = {x: {y: 2}},
+      message = "Expected $.x.y = 1 to equal 2.";
+
+    expect(compareEquals(actual, expected).message).toEqual(message);
+  });
+
+  it("formats property access so that it's valid JavaScript", function() {
+    var actual = {'my prop': 1},
+      expected = {'my prop': 2},
+      message = "Expected $['my prop'] = 1 to equal 2.";
+
+    expect(compareEquals(actual, expected).message).toEqual(message);
+  });
+
+  it("reports missing properties", function() {
+    var actual = {x: {}},
+      expected = {x: {y: 1}},
+      message =
+        "Expected $.x to have properties\n" +
+        "    y: 1";
+
+    expect(compareEquals(actual, expected).message).toEqual(message);
+  });
+
+  it("reports extra properties", function() {
+    var actual = {x: {y: 1, z: 2}},
+      expected = {x: {}},
+      message =
+        "Expected $.x not to have properties\n" +
+        "    y: 1\n" +
+        "    z: 2";
+
+    expect(compareEquals(actual, expected).message).toEqual(message);
+  });
+
+  it("pretty-prints properties", function() {
+    var actual = {x: {y: 'foo bar'}},
+      expected = {x: {}},
+      message =
+        "Expected $.x not to have properties\n" +
+        "    y: 'foo bar'"
+
+    expect(compareEquals(actual, expected).message).toEqual(message);
+  });
+
+  it("reports extra and missing properties together", function() {
+    var actual = {x: {y: 1, z: 2, f: 4}},
+      expected = {x: {y: 1, z: 2, g: 3}},
+      message =
+        "Expected $.x to have properties\n" +
+        "    g: 3\n" +
+        "Expected $.x not to have properties\n" +
+        "    f: 4";
+
+    expect(compareEquals(actual, expected).message).toEqual(message);
+  });
+
+  it("reports extra and missing properties of the root-level object", function() {
+    var actual = {x: 1},
+      expected = {a: 1},
+      message =
+        "Expected object to have properties\n" +
+        "    a: 1\n" +
+        "Expected object not to have properties\n" +
+        "    x: 1";
+
+    expect(compareEquals(actual, expected).message).toEqual(message);
+  });
+
+  it("reports multiple incorrect values", function() {
+    var actual = {x: 1, y: 2},
+      expected = {x: 3, y: 4},
+      message =
+        "Expected $.x = 1 to equal 3.\n" +
+        "Expected $.y = 2 to equal 4.";
+
+    expect(compareEquals(actual, expected).message).toEqual(message);
+  });
+
+  it("reports mismatch between actual child object and expected child number", function() {
+    var actual = {x: {y: 2}},
+      expected = {x: 1},
+      message = "Expected $.x = Object({ y: 2 }) to equal 1.";
+
+    expect(compareEquals(actual, expected).message).toEqual(message);
+  });
+
+  it("uses the default failure message if actual is not an object", function() {
+    var actual = 1,
+      expected = {x: {}},
+      message = "Expected 1 to equal Object({ x: Object({  }) }).";
+
+    expect(compareEquals(actual, expected).message).toEqual(message);
+  });
+
+  it("uses the default failure message if expected is not an object", function() {
+    var actual = {x: {}},
+      expected = 1,
+      message = "Expected Object({ x: Object({  }) }) to equal 1.";
+
+    expect(compareEquals(actual, expected).message).toEqual(message);
+  });
+
+  it("uses the default failure message given arrays with different lengths", function() {
+    var actual = [1, 2],
+      expected = [1, 2, 3],
+      message =
+        "Expected [ 1, 2 ] to equal [ 1, 2, 3 ].";
+
+    expect(compareEquals(actual, expected).message).toEqual(message);
+  });
+
+  it("reports a mismatch between elements of equal-length arrays", function() {
+    var actual = [1, 2, 5],
+      expected = [1, 2, 3],
+      message = "Expected $[2] = 5 to equal 3.";
+
+    expect(compareEquals(actual, expected).message).toEqual(message);
+  });
+
+  it("reports a mismatch between multiple array elements", function() {
+    var actual = [2, 2, 5],
+      expected = [1, 2, 3],
+      message =
+        "Expected $[0] = 2 to equal 1.\n" +
+        "Expected $[2] = 5 to equal 3.";
+
+    expect(compareEquals(actual, expected).message).toEqual(message);
+  });
+
+  it("reports a mismatch between properties of objects in arrays", function() {
+    var actual = [{x: 1}],
+      expected = [{x: 2}],
+      message = "Expected $[0].x = 1 to equal 2.";
+
+    expect(compareEquals(actual, expected).message).toEqual(message);
+  });
+
+  it("reports a mismatch between arrays in objects", function() {
+    var actual = {x: [1]},
+      expected = {x: [2]},
+      message =
+        "Expected $.x[0] = 1 to equal 2.";
+
+    expect(compareEquals(actual, expected).message).toEqual(message);
+  });
+
+  it("reports mismatches between nested arrays", function() {
+    var actual = [[1]],
+      expected = [[2]],
+      message =
+        "Expected $[0][0] = 1 to equal 2.";
+
+    expect(compareEquals(actual, expected).message).toEqual(message);
+  });
+
+  it("reports mismatches involving NaN", function() {
+    var actual = {x: 0},
+      expected = {x: 0/0},
+      message = "Expected $.x = 0 to equal NaN.";
+
+    expect(compareEquals(actual, expected).message).toEqual(message);
+  });
+
+  it("reports mismatches involving regular expressions", function() {
+    var actual = {x: '1'},
+      expected = {x: /1/},
+      message = "Expected $.x = '1' to equal /1/.";
+
+    expect(compareEquals(actual, expected).message).toEqual(message);
+  });
+
+  it("reports mismatches involving infinities", function() {
+    var actual = {x: 0},
+      expected = {x: 1/0},
+      message = "Expected $.x = 0 to equal Infinity.";
+
+    expect(compareEquals(actual, expected).message).toEqual(message);
+  });
+
+  it("reports mismatches involving booleans", function() {
+    var actual = {x: false},
+      expected = {x: true},
+      message = "Expected $.x = false to equal true.";
+
+    expect(compareEquals(actual, expected).message).toEqual(message);
+  });
+
+  it("reports mismatches involving strings", function() {
+    var actual = {x: 'foo'},
+      expected = {x: 'bar'},
+      message = "Expected $.x = 'foo' to equal 'bar'.";
+
+    expect(compareEquals(actual, expected).message).toEqual(message);
+  });
+
+  it("reports mismatches involving undefined", function() {
+    var actual = {x: void 0},
+      expected = {x: 0},
+      message = "Expected $.x = undefined to equal 0.";
+
+    expect(compareEquals(actual, expected).message).toEqual(message);
+  });
+
+  it("reports mismatches involving null", function() {
+    var actual = {x: null},
+      expected = {x: 0},
+      message = "Expected $.x = null to equal 0.";
+
+    expect(compareEquals(actual, expected).message).toEqual(message);
+  });
+
+  it("reports mismatches between objects with different constructors", function () {
+    function Foo() {}
+    function Bar() {}
+
+    var actual = {x: new Foo()},
+        expected = {x: new Bar()},
+        message = "Expected $.x to be a kind of Bar, but was Foo({  }).";
+
+    expect(compareEquals(actual, expected).message).toEqual(message);
+  });
+
+  it("reports type mismatches at the root level", function () {
+    function Foo() {}
+    function Bar() {}
+
+    var actual = new Foo(),
+      expected = new Bar(),
+      message = "Expected object to be a kind of Bar, but was Foo({  }).";
+
+    expect(compareEquals(actual, expected).message).toEqual(message);
+  });
+
+  it("reports mismatches between objects with their own constructor property", function () {
+    function Foo() {}
+    function Bar() {}
+
+    var actual = {x: {constructor: 'blerf'}},
+        expected = {x: {constructor: 'ftarrh'}},
+        message = "Expected $.x.constructor = 'blerf' to equal 'ftarrh'.";
+
+    expect(compareEquals(actual, expected).message).toEqual(message);
+  });
+
+  it("reports mismatches between an object with a real constructor and one with its own constructor property", function () {
+    function Foo() {}
+    function Bar() {}
+
+    var actual = {x: {}},
+      expected = {x: {constructor: 'ftarrh'}},
+      message =
+        "Expected $.x to have properties\n" +
+        "    constructor: 'ftarrh'";
+
+    expect(compareEquals(actual, expected).message).toEqual(message);
+    expect(compareEquals(expected, actual).message).toEqual(
+      "Expected $.x not to have properties\n    constructor: 'ftarrh'"
+    );
+  });
+
+  it("reports mismatches between 0 and -0", function() {
+    var actual = {x: 0},
+      expected = {x: -0},
+      message = "Expected $.x = 0 to equal -0.";
+
+    expect(compareEquals(actual, expected).message).toEqual(message);
+  });
+
+  it("reports mismatches between Errors", function() {
+    var actual = {x: new Error("the error you got")},
+      expected = {x: new Error("the error you want")},
+      message = "Expected $.x = Error: the error you got to equal Error: the error you want.";
+
+    expect(compareEquals(actual, expected).message).toEqual(message);
+  });
+
+  it("reports mismatches between Functions", function() {
+    var actual = {x: function() {}},
+      expected = {x: function() {}},
+      message = "Expected $.x = Function to equal Function.";
+
+    expect(compareEquals(actual, expected).message).toEqual(message);
+  });
+
+  it("does not report deep mismatches within Sets", function() {
+    // TODO: implement deep comparison of set elements
+    jasmine.getEnv().requireFunctioningSets();
+
+    var actual = new Set([1]),
+      expected = new Set([2]),
+      message = 'Expected Set( 1 ) to equal Set( 2 ).';
+
+    expect(compareEquals(actual, expected).message).toEqual(message);
+  });
+
+  it("reports mismatches between Sets nested in objects", function() {
+    jasmine.getEnv().requireFunctioningSets();
+
+    var actual = {sets: [new Set([1])]},
+      expected = {sets: [new Set([2])]},
+      message = "Expected $.sets[0] = Set( 1 ) to equal Set( 2 ).";
+
+    expect(compareEquals(actual, expected).message).toEqual(message);
+  });
+
+  it("reports mismatches between Sets of different lengths", function() {
+    jasmine.getEnv().requireFunctioningSets();
+
+    var actual = new Set([1, 2]),
+      expected = new Set([2]),
+      message = 'Expected Set( 1, 2 ) to equal Set( 2 ).';
+
+    expect(compareEquals(actual, expected).message).toEqual(message);
+  });
+
+  function isNotRunningInBrowser() {
+    return typeof document === 'undefined'
+  }
+
+  it("reports mismatches between DOM nodes with different tags", function() {
+    if(isNotRunningInBrowser()) {
+      return;
+    }
+
+    var actual = {a: document.createElement('div')},
+      expected = {a: document.createElement('p')},
+      message = 'Expected $.a = HTMLNode to equal HTMLNode.';
+
+    expect(compareEquals(actual, expected).message).toEqual(message);
+  });
+
+  it('reports mismatches between DOM nodes with different content', function() {
+    if(isNotRunningInBrowser()) {
+      return;
+    }
+
+    var nodeA = document.createElement('div'),
+      nodeB = document.createElement('div');
+
+    nodeA.innerText = 'foo'
+    nodeB.innerText = 'bar'
+
+    var actual = {a: nodeA},
+      expected = {a: nodeB},
+      message = 'Expected $.a = HTMLNode to equal HTMLNode.';
+
+    expect(compareEquals(actual, expected).message).toEqual(message);
+  })
+
+  it("reports mismatches between a DOM node and a bare Object", function() {
+    if(isNotRunningInBrowser()) {
+      return;
+    }
+
+    var actual = {a: document.createElement('div')},
+      expected = {a: {}},
+      message = 'Expected $.a = HTMLNode to equal Object({  }).';
+
+    expect(compareEquals(actual, expected).message).toEqual(message);
+  });
+
+  it("reports asymmetric mismatches", function() {
+    var actual = {a: 1},
+      expected = {a: jasmineUnderTest.any(String)},
+      message = 'Expected $.a = 1 to equal <jasmine.any(String)>.';
+
+    expect(compareEquals(actual, expected).message).toEqual(message);
+    expect(compareEquals(actual, expected).pass).toBe(false)
+  });
+
+  it("reports asymmetric mismatches when the asymmetric comparand is the actual value", function() {
+    var actual = {a: jasmineUnderTest.any(String)},
+      expected = {a: 1},
+      message = 'Expected $.a = <jasmine.any(String)> to equal 1.';
+
+    expect(compareEquals(actual, expected).message).toEqual(message);
+    expect(compareEquals(actual, expected).pass).toBe(false)
+  });
+
+  it("does not report a mismatch when asymmetric matchers are satisfied", function() {
+    var actual = {a: 'a'},
+      expected = {a: jasmineUnderTest.any(String)},
+      message = 'Expected $.a = 1 to equal <jasmine.any(String)>.';
+
+    expect(compareEquals(actual, expected).pass).toBe(true)
+  });
+
+  it("works on big complex stuff", function() {
+    var actual = {
+      foo: [
+        {bar: 1, things: ['a', 'b']},
+        {bar: 2, things: ['a', 'b']}
+      ],
+      baz: [
+        {a: {b: 1}}
+      ],
+      quux: 1,
+      nan: 0,
+      aRegexp: 'hi',
+      inf: -1/0,
+      boolean: false,
+      notDefined: 0,
+      aNull: void 0
+    }
+
+    var expected = {
+      foo: [
+        {bar: 2, things: ['a', 'b', 'c']},
+        {bar: 2, things: ['a', 'd']}
+      ],
+      baz: [
+        {a: {b: 1, c: 1}}
+      ],
+      quux: [],
+      nan: 0/0,
+      aRegexp: /hi/,
+      inf: 1/0,
+      boolean: true,
+      notDefined: void 0,
+      aNull: null
+    }
+
+    var message =
+      'Expected $.foo[0].bar = 1 to equal 2.\n' +
+      "Expected $.foo[0].things = [ 'a', 'b' ] to equal [ 'a', 'b', 'c' ].\n" +
+      "Expected $.foo[1].things[1] = 'b' to equal 'd'.\n" +
+      'Expected $.baz[0].a to have properties\n' +
+      '    c: 1\n' +
+      'Expected $.quux = 1 to equal [  ].\n' +
+      'Expected $.nan = 0 to equal NaN.\n' +
+      "Expected $.aRegexp = 'hi' to equal /hi/.\n" +
+      'Expected $.inf = -Infinity to equal Infinity.\n' +
+      'Expected $.boolean = false to equal true.\n' +
+      'Expected $.notDefined = 0 to equal undefined.\n' +
+      'Expected $.aNull = undefined to equal null.'
+
+    expect(compareEquals(actual, expected).message).toEqual(message);
+  })
 });

src/core/PrettyPrinter.js

@@ -145,7 +145,13 @@ getJasmineRequireObj().pp = function(j$) {
   };
 
   StringPrettyPrinter.prototype.emitObject = function(obj) {
-    var constructorName = obj.constructor ? j$.fnNameFor(obj.constructor) : 'null';
+    var ctor = obj.constructor,
+        constructorName;
+
+    constructorName = typeof ctor === 'function' && obj instanceof ctor ?
+      j$.fnNameFor(obj.constructor) :
+      'null';
+
     this.append(constructorName);
 
     if (this.ppNestLevel_ > j$.MAX_PRETTY_PRINT_DEPTH) {

src/core/matchers/DiffBuilder.js

@@ -0,0 +1,33 @@
+getJasmineRequireObj().DiffBuilder = function(j$) {
+  return function DiffBuilder() {
+    var path = new j$.ObjectPath(),
+        mismatches = [];
+
+    return {
+      record: function (actual, expected, formatter) {
+        formatter = formatter || defaultFormatter;
+        mismatches.push(formatter(actual, expected, path));
+      },
+
+      getMessage: function () {
+        return mismatches.join('\n');
+      },
+
+      withPath: function (pathComponent, block) {
+        var oldPath = path;
+        path = path.add(pathComponent);
+        block();
+        path = oldPath;
+      }
+    };
+
+    function defaultFormatter (actual, expected, path) {
+      return 'Expected ' +
+        path + (path.depth() ? ' = ' : '') +
+        j$.pp(actual) +
+        ' to equal ' +
+        j$.pp(expected) +
+        '.';
+    }
+  };
+};

src/core/matchers/NullDiffBuilder.js

@@ -0,0 +1,10 @@
+getJasmineRequireObj().NullDiffBuilder = function(j$) {
+  return function() {
+    return {
+      withPath: function(_, block) {
+        block();
+      },
+      record: function() {}
+    };
+  };
+};

src/core/matchers/ObjectPath.js

@@ -0,0 +1,47 @@
+getJasmineRequireObj().ObjectPath = function(j$) {
+  function ObjectPath(components) {
+    this.components = components || [];
+  }
+
+  ObjectPath.prototype.toString = function() {
+    if (this.components.length) {
+      return '$' + map(this.components, formatPropertyAccess).join('');
+    } else {
+      return '';
+    }
+  };
+
+  ObjectPath.prototype.add = function(component) {
+    return new ObjectPath(this.components.concat([component]));
+  };
+
+  ObjectPath.prototype.depth = function() {
+    return this.components.length;
+  };
+
+  function formatPropertyAccess(prop) {
+    if (typeof prop === 'number') {
+      return '[' + prop + ']';
+    }
+
+    if (isValidIdentifier(prop)) {
+      return '.' + prop;
+    }
+
+    return '[\'' + prop + '\']';
+  }
+
+  function map(array, fn) {
+    var results = [];
+    for (var i = 0; i < array.length; i++) {
+      results.push(fn(array[i]));
+    }
+    return results;
+  }
+
+  function isValidIdentifier(string) {
+    return /^[A-Za-z\$_][A-Za-z0-9\$_]*$/.test(string);
+  }
+
+  return ObjectPath;
+};

src/core/matchers/matchersUtil.js

@@ -2,11 +2,7 @@ getJasmineRequireObj().matchersUtil = function(j$) {
   // TODO: what to do about jasmine.pp not being inject? move to JSON.stringify? gut PrettyPrinter?
 
   return {
-    equals: function(a, b, customTesters) {
-      customTesters = customTesters || [];
-
-      return eq(a, b, [], [], customTesters);
-    },
+    equals: equals,
 
     contains: function(haystack, needle, customTesters) {
       customTesters = customTesters || [];
@@ -19,7 +15,7 @@ getJasmineRequireObj().matchersUtil = function(j$) {
         (!!haystack && !haystack.indexOf))
       {
         for (var i = 0; i < haystack.length; i++) {
-          if (eq(haystack[i], needle, [], [], customTesters)) {
+          if (equals(haystack[i], needle, customTesters)) {
             return true;
           }
         }
@@ -59,67 +55,113 @@ getJasmineRequireObj().matchersUtil = function(j$) {
     return obj && j$.isA_('Function', obj.asymmetricMatch);
   }
 
-  function asymmetricMatch(a, b, customTesters) {
+  function asymmetricMatch(a, b, customTesters, diffBuilder) {
     var asymmetricA = isAsymmetric(a),
-        asymmetricB = isAsymmetric(b);
+        asymmetricB = isAsymmetric(b),
+        result;
 
     if (asymmetricA && asymmetricB) {
       return undefined;
     }
 
     if (asymmetricA) {
-      return a.asymmetricMatch(b, customTesters);
+      result = a.asymmetricMatch(b, customTesters);
+      diffBuilder.record(a, b);
+      return result;
     }
 
     if (asymmetricB) {
-      return b.asymmetricMatch(a, customTesters);
+      result = b.asymmetricMatch(a, customTesters);
+      diffBuilder.record(a, b);
+      return result;
     }
   }
 
+  function equals(a, b, customTesters, diffBuilder) {
+    customTesters = customTesters || [];
+    diffBuilder = diffBuilder || j$.NullDiffBuilder();
+
+    return eq(a, b, [], [], customTesters, diffBuilder);
+  }
+
   // Equality function lovingly adapted from isEqual in
   //   [Underscore](http://underscorejs.org)
-  function eq(a, b, aStack, bStack, customTesters) {
-    var result = true;
+  function eq(a, b, aStack, bStack, customTesters, diffBuilder) {
+    var result = true, i;
 
-    var asymmetricResult = asymmetricMatch(a, b, customTesters);
+    var asymmetricResult = asymmetricMatch(a, b, customTesters, diffBuilder);
     if (!j$.util.isUndefined(asymmetricResult)) {
       return asymmetricResult;
     }
 
-    for (var i = 0; i < customTesters.length; i++) {
+    for (i = 0; i < customTesters.length; i++) {
       var customTesterResult = customTesters[i](a, b);
       if (!j$.util.isUndefined(customTesterResult)) {
+        if (!customTesterResult) {
+          diffBuilder.record(a, b);
+        }
         return customTesterResult;
       }
     }
 
     if (a instanceof Error && b instanceof Error) {
-      return a.message == b.message;
+      result = a.message == b.message;
+      if (!result) {
+        diffBuilder.record(a, b);
+      }
+      return result;
     }
 
     // Identical objects are equal. `0 === -0`, but they aren't identical.
     // See the [Harmony `egal` proposal](http://wiki.ecmascript.org/doku.php?id=harmony:egal).
-    if (a === b) { return a !== 0 || 1 / a == 1 / b; }
+    if (a === b) {
+      result = a !== 0 || 1 / a == 1 / b;
+      if (!result) {
+        diffBuilder.record(a, b);
+      }
+      return result;
+    }
     // A strict comparison is necessary because `null == undefined`.
-    if (a === null || b === null) { return a === b; }
+    if (a === null || b === null) {
+      result = a === b;
+      if (!result) {
+        diffBuilder.record(a, b);
+      }
+      return result;
+    }
     var className = Object.prototype.toString.call(a);
-    if (className != Object.prototype.toString.call(b)) { return false; }
+    if (className != Object.prototype.toString.call(b)) {
+      diffBuilder.record(a, b);
+      return false;
+    }
     switch (className) {
       // Strings, numbers, dates, and booleans are compared by value.
       case '[object String]':
         // Primitives and their corresponding object wrappers are equivalent; thus, `"5"` is
         // equivalent to `new String("5")`.
-        return a == String(b);
+        result = a == String(b);
+        if (!result) {
+          diffBuilder.record(a, b);
+        }
+        return result;
       case '[object Number]':
         // `NaN`s are equivalent, but non-reflexive. An `egal` comparison is performed for
         // other numeric values.
-        return a != +a ? b != +b : (a === 0 ? 1 / a == 1 / b : a == +b);
+        result = a != +a ? b != +b : (a === 0 ? 1 / a == 1 / b : a == +b);
+        if (!result) {
+          diffBuilder.record(a, b);
+        }
+        return result;
       case '[object Date]':
       case '[object Boolean]':
         // Coerce dates and booleans to numeric primitive values. Dates are compared by their
         // millisecond representations. Note that invalid dates with millisecond representations
         // of `NaN` are not equivalent.
-        return +a == +b;
+        result = +a == +b;
+        if (!result) {
+          diffBuilder.record(a, b);
+        }
+        return result;
       // RegExps are compared by their source patterns and flags.
       case '[object RegExp]':
         return a.source == b.source &&
@@ -127,14 +169,21 @@ getJasmineRequireObj().matchersUtil = function(j$) {
           a.multiline == b.multiline &&
           a.ignoreCase == b.ignoreCase;
     }
-    if (typeof a != 'object' || typeof b != 'object') { return false; }
+    if (typeof a != 'object' || typeof b != 'object') {
+      diffBuilder.record(a, b);
+      return false;
+    }
 
     var aIsDomNode = j$.isDomNode(a);
     var bIsDomNode = j$.isDomNode(b);
     if (aIsDomNode && bIsDomNode) {
       // At first try to use DOM3 method isEqualNode
       if (a.isEqualNode) {
-        return a.isEqualNode(b);
+        result = a.isEqualNode(b);
+        if (!result) {
+          diffBuilder.record(a, b);
+        }
+        return result;
       }
       // IE8 doesn't support isEqualNode, try to use outerHTML && innerText
       var aIsElement = a instanceof Element;
@@ -168,17 +217,21 @@ getJasmineRequireObj().matchersUtil = function(j$) {
     if (className == '[object Array]') {
       size = a.length;
       if (size !== b.length) {
+        diffBuilder.record(a, b);
         return false;
       }
 
-      while (size--) {
-        result = eq(a[size], b[size], aStack, bStack, customTesters);
-        if (!result) {
-          return false;
-        }
+      for (i = 0; i < size; i++) {
+        diffBuilder.withPath(i, function() {
+          result = eq(a[i], b[i], aStack, bStack, customTesters, diffBuilder) && result;
+        });
+      }
+      if (!result) {
+        return false;
       }
     } else if (className == '[object Set]') {
       if (a.size != b.size) {
+        diffBuilder.record(a, b);
         return false;
       }
       var iterA = a.values(), iterB = b.values();
@@ -186,7 +239,8 @@ getJasmineRequireObj().matchersUtil = function(j$) {
       do {
         valA = iterA.next();
         valB = iterB.next();
-        if (!eq(valA.value, valB.value, aStack, bStack, customTesters)) {
+        if (!eq(valA.value, valB.value, aStack, bStack, customTesters, j$.NullDiffBuilder())) {
+          diffBuilder.record(a, b);
           return false;
         }
       } while (!valA.done && !valB.done);
@@ -195,8 +249,12 @@ getJasmineRequireObj().matchersUtil = function(j$) {
       // Objects with different constructors are not equivalent, but `Object`s
       // or `Array`s from different frames are.
       var aCtor = a.constructor, bCtor = b.constructor;
-      if (aCtor !== bCtor && !(isObjectConstructor(aCtor) &&
-                               isObjectConstructor(bCtor))) {
+      if (aCtor !== bCtor &&
+          isFunction(aCtor) && isFunction(bCtor) &&
+          a instanceof aCtor && b instanceof bCtor &&
+          !(aCtor instanceof aCtor && bCtor instanceof bCtor)) {
+
+        diffBuilder.record(a, b, constructorsAreDifferentFormatter);
         return false;
       }
     }
@@ -206,52 +264,66 @@ getJasmineRequireObj().matchersUtil = function(j$) {
     size = aKeys.length;
 
     // Ensure that both objects contain the same number of properties before comparing deep equality.
-    if (keys(b, className == '[object Array]').length !== size) { return false; }
-
-    while (size--) {
-      key = aKeys[size];
-      // Deep compare each member
-      result = has(b, key) && eq(a[key], b[key], aStack, bStack, customTesters);
-
-      if (!result) {
-        return false;
-      }
+    if (keys(b, className == '[object Array]').length !== size) {
+      diffBuilder.record(a, b, objectKeysAreDifferentFormatter);
+      return false;
     }
+
+    for (i = 0; i < size; i++) {
+      key = aKeys[i];
+      // Deep compare each member
+      if (!j$.util.has(b, key)) {
+        diffBuilder.record(a, b, objectKeysAreDifferentFormatter);
+        result = false;
+        continue;
+      }
+
+      diffBuilder.withPath(key, function() {
+        if(!eq(a[key], b[key], aStack, bStack, customTesters, diffBuilder)) {
+          result = false;
+        }
+      });
+    }
+
+    if (!result) {
+      return false;
+    }
+
     // Remove the first object from the stack of traversed objects.
     aStack.pop();
     bStack.pop();
 
     return result;
+  }
 
-    function keys(obj, isArray) {
-      var allKeys = Object.keys ? Object.keys(obj) :
-        (function(o) {
-            var keys = [];
-            for (var key in o) {
-                if (has(o, key)) {
-                    keys.push(key);
-                }
-            }
-            return keys;
-        })(obj);
-
-      if (!isArray) {
-        return allKeys;
-      }
-
-      var extraKeys = [];
-      if (allKeys.length === 0) {
-          return allKeys;
-      }
-
-      for (var x = 0; x < allKeys.length; x++) {
-          if (!allKeys[x].match(/^[0-9]+$/)) {
-              extraKeys.push(allKeys[x]);
+  function keys(obj, isArray) {
+    var allKeys = Object.keys ? Object.keys(obj) :
+      (function(o) {
+          var keys = [];
+          for (var key in o) {
+              if (j$.util.has(o, key)) {
+                  keys.push(key);
+              }
           }
-      }
+          return keys;
+      })(obj);
 
-      return extraKeys;
+    if (!isArray) {
+      return allKeys;
     }
+
+    if (allKeys.length === 0) {
+        return allKeys;
+    }
+
+    var extraKeys = [];
+    for (var i in allKeys) {
+      if (!allKeys[i].match(/^[0-9]+$/)) {
+        extraKeys.push(allKeys[i]);
+      }
+    }
+
+    return extraKeys;
   }
 
   function has(obj, key) {
@@ -262,11 +334,44 @@ getJasmineRequireObj().matchersUtil = function(j$) {
     return typeof obj === 'function';
   }
 
-  function isObjectConstructor(ctor) {
-    // aCtor instanceof aCtor is true for the Object and Function
-    // constructors (since a constructor is-a Function and a function is-a
-    // Object). We don't just compare ctor === Object because the constructor
-    // might come from a different frame with different globals.
-    return isFunction(ctor) && ctor instanceof ctor;
+  function objectKeysAreDifferentFormatter(actual, expected, path) {
+    var missingProperties = j$.util.objectDifference(expected, actual),
+        extraProperties = j$.util.objectDifference(actual, expected),
+        missingPropertiesMessage = formatKeyValuePairs(missingProperties),
+        extraPropertiesMessage = formatKeyValuePairs(extraProperties),
+        messages = [];
+
+    if (!path.depth()) {
+      path = 'object';
+    }
+
+    if (missingPropertiesMessage.length) {
+      messages.push('Expected ' + path + ' to have properties' + missingPropertiesMessage);
+    }
+
+    if (extraPropertiesMessage.length) {
+      messages.push('Expected ' + path + ' not to have properties' + extraPropertiesMessage);
+    }
+
+    return messages.join('\n');
+  }
+
+  function constructorsAreDifferentFormatter(actual, expected, path) {
+    if (!path.depth()) {
+      path = 'object';
+    }
+
+    return 'Expected ' +
+      path + ' to be a kind of ' +
+      expected.constructor.name +
+      ', but was ' + j$.pp(actual) + '.';
+  }
+
+  function formatKeyValuePairs(obj) {
+    var formatted = '';
+    for (var key in obj) {
+      formatted += '\n    ' + key + ': ' + j$.pp(obj[key]);
+    }
+    return formatted;
   }
 };

src/core/matchers/toEqual.js

@@ -1,4 +1,4 @@
-getJasmineRequireObj().toEqual = function() {
+getJasmineRequireObj().toEqual = function(j$) {
 
   function toEqual(util, customEqualityTesters) {
     customEqualityTesters = customEqualityTesters || [];
@@ -6,10 +6,14 @@ getJasmineRequireObj().toEqual = function() {
     return {
       compare: function(actual, expected) {
         var result = {
-          pass: false
-        };
+            pass: false
+          },
+          diffBuilder = j$.DiffBuilder();
 
-        result.pass = util.equals(actual, expected, customEqualityTesters);
+        result.pass = util.equals(actual, expected, customEqualityTesters, diffBuilder);
+
+        // TODO: only set error message if test fails
+        result.message = diffBuilder.getMessage();
 
         return result;
       }

src/core/requireCore.js

@@ -54,6 +54,9 @@ var getJasmineRequireObj = (function (jasmineGlobal) {
     j$.TreeProcessor = jRequire.TreeProcessor();
     j$.version = jRequire.version();
     j$.Order = jRequire.Order();
+    j$.DiffBuilder = jRequire.DiffBuilder(j$);
+    j$.NullDiffBuilder = jRequire.NullDiffBuilder(j$);
+    j$.ObjectPath = jRequire.ObjectPath(j$);
 
     j$.matchers = jRequire.requireMatchers(jRequire, j$);
 

src/core/util.js

@@ -67,5 +67,21 @@ getJasmineRequireObj().util = function() {
     return descriptor;
   };
 
+  util.objectDifference = function(obj, toRemove) {
+    var diff = {};
+
+    for (var key in obj) {
+      if (util.has(obj, key) && !util.has(toRemove, key)) {
+        diff[key] = obj[key];
+      }
+    }
+
+    return diff;
+  };
+
+  util.has = function(obj, key) {
+    return Object.prototype.hasOwnProperty.call(obj, key);
+  };
+
   return util;
 };