The goog.testing.PropertyReplacer Class

goog.testing.PropertyReplacer()

Helper class for stubbing out variables and object properties for unit tests. This class can change the value of some variables before running the test cases, and to reset them in the tearDown phase. See googletest.StubOutForTesting as an analogy in Python: http://protobuf.googlecode.com/svn/trunk/python/stubout.py Example usage: 

var stubs = new goog.testing.PropertyReplacer();

 function setUp() {
   // Mock functions used in all test cases.
   stubs.set(Math, 'random', function() {
     return 4;  // Chosen by fair dice roll. Guaranteed to be random.
   });
 }

 function tearDown() {
   stubs.reset();
 }

 function testThreeDice() {
   // Mock a constant used only in this test case.
   stubs.set(goog.global, 'DICE_COUNT', 3);
   assertEquals(12, rollAllDice());
 }
Constraints on altered objects:

.remove(obj, key)

Deletes the key from the object while saving its original value.

obj {Object|Function}
The JavaScript or native object or function to alter. See the constraints in the class description.
key {string}
The key to delete.

.replace(obj, key, value)

Changes an existing value in an object to another one of the same type while saving its original state. The advantage of {@code replace} over {@link #set} is that {@code replace} protects against typos and erroneously passing tests after some members have been renamed during a refactoring.

obj {Object|Function}
The JavaScript or native object or function to alter. See the constraints in the class description.
key {string}
The key to change the value for. It has to be present either in {@code obj} or in its prototype chain.
value {*}
The new value to set. It has to have the same type as the original value. The types are compared with {@link goog.typeOf}.
@throws
{Error} In case of missing key or type mismatch.

.reset()

Resets all changes made by goog.testing.PropertyReplacer.prototype.set.

.set(obj, key, value)

Adds or changes a value in an object while saving its original state.

obj {Object|Function}
The JavaScript or native object or function to alter. See the constraints in the class description.
key {string}
The key to change the value for.
value {*}
The new value to set.

.setPath(path, value)

Builds an object structure for the provided namespace path. Doesn't overwrite those prefixes of the path that are already objects or functions.

path {string}
The path to create or alter, e.g. 'goog.ui.Menu'.
value {*}
The value to set.

Documentation generated using JvJsDoc, version 0.5 on 2012-09-03.