jasmine/spec/core/SpyRegistrySpec.js

describe("SpyRegistry", function() {
  describe("#spyOn", function() {
    it("checks for the existence of the object", function() {
      var spyRegistry = new j$.SpyRegistry();
      expect(function() {
        spyRegistry.spyOn(void 0, 'pants');
      }).toThrowError(/could not find an object/);
    });

    it("checks for the existence of the method", function() {
      var spyRegistry = new j$.SpyRegistry(),
        subject = {};

      expect(function() {
        spyRegistry.spyOn(subject, 'pants');
      }).toThrowError(/method does not exist/);
    });

    it("checks if it has already been spied upon", function() {
      var spies = [],
        spyRegistry = new j$.SpyRegistry({currentSpies: function() { return spies; }}),
        subject = { spiedFunc: function() {} };

      spyRegistry.spyOn(subject, 'spiedFunc');

      expect(function() {
        spyRegistry.spyOn(subject, 'spiedFunc');
      }).toThrowError(/has already been spied upon/);
    });

    it("overrides the method on the object and returns the spy", function() {
      var originalFunctionWasCalled = false,
        spyRegistry = new j$.SpyRegistry(),
        subject = { spiedFunc: function() { originalFunctionWasCalled = true; } };

      var spy = spyRegistry.spyOn(subject, 'spiedFunc');

      expect(subject.spiedFunc).toEqual(spy);
    });
  });

  describe("#clearSpies", function() {
    it("restores the original functions on the spied-upon objects", function() {
      var spies = [],
        spyRegistry = new j$.SpyRegistry({currentSpies: function() { return spies; }}),
        originalFunction = function() {},
        subject = { spiedFunc: originalFunction };

      spyRegistry.spyOn(subject, 'spiedFunc');
      spyRegistry.clearSpies();

      expect(subject.spiedFunc).toBe(originalFunction);
    });
  });
});