Mocking and stubbing in Ruby - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is mocking in Ruby testing?

Mocking is creating fake objects that simulate real objects' behavior to test interactions without using the real objects.

beginner

What does stubbing mean in Ruby tests?

Stubbing means replacing a method with a fake one that returns a specific value, so the test does not depend on the real method's behavior.

beginner

How do you create a stub for a method in RSpec?

Use allow(object).to receive(:method).and_return(value) to make the method return the value during tests.

intermediate

What is the difference between a mock and a stub?

A stub provides canned responses to method calls, while a mock also verifies that certain methods were called with expected arguments.

beginner

Why use mocking and stubbing in tests?

They isolate the code being tested by replacing dependencies, making tests faster, more reliable, and focused on specific behavior.

Which RSpec method is used to stub a method?

A mock(object).method

B allow(object).to receive(:method).and_return(value)

C expect(object).to receive(:method)

D stub(object).method

In RSpec, allow(object).to receive(:method).and_return(value) is used to stub a method.

What does a mock object do besides stubbing methods?

A Verifies that methods are called with expected arguments

B Runs the real method implementation

C Deletes the original object

D Automatically fixes bugs

Mocks verify that certain methods are called with expected arguments during tests.

Why is stubbing useful in tests?

A To replace slow or unreliable methods with fixed return values

B To make tests run slower

C To delete code

D To create real database records

Stubbing replaces methods with fixed return values to make tests faster and more reliable.

Which of these is NOT a benefit of mocking and stubbing?

A Isolating the code under test

B Controlling test environment

C Speeding up tests

D Making tests dependent on external services

Mocking and stubbing reduce dependency on external services, not increase it.

In RSpec, how do you check that a method was called on a mock?

A object.method

B allow(object).to receive(:method)

C expect(object).to receive(:method)

D stub(object).method

Use expect(object).to receive(:method) to verify a method call on a mock.

Explain in your own words what mocking and stubbing are and why they are useful in Ruby testing.

Think about how you can replace parts of your code to test only what you want.

Describe how you would stub a method in RSpec and how you would verify a method call using a mock.

Remember the keywords 'allow' and 'expect' in RSpec.