Jasmine JavaScript Testing Framework Jasmine Spies and Mocking

Question 1

What function creates a spy on an existing object method in Jasmine?

Accepted Answer

spyOn(obj, 'method')

Answer

spyOn(obj, 'method') replaces the named method on obj with a Jasmine spy that tracks calls.

Question 2

Which property returns the number of times a Jasmine spy was called?

Accepted Answer

spy.calls.count()

Answer

spy.calls.count() is the method on the calls object that returns the total invocation count.

Question 3

What does spyOn(obj, 'method').and.returnValue(42) do?

Accepted Answer

Makes the spy return 42 instead of calling the real method

Answer

returnValue(42) configures the spy to always return 42 without invoking the original implementation.

Question 4

How do you configure a Jasmine spy to invoke the original implementation?

Accepted Answer

.and.callThrough()

Answer

callThrough() tells the spy to forward the call to the real method while still tracking it.

Question 5

What does jasmine.createSpyObj('MyClass', ['save', 'load']) return?

Accepted Answer

A plain object with save and load as spy functions

Answer

createSpyObj creates a mock object whose named methods are all individual spies you can configure.

Jasmine JavaScript Testing Framework Practice Test