UNIT TESTING

What is Unit Testing?

defined as a type of software testing where individual units/ components of a software are tested.

Why is it Important?

Unit Tests fix bug early in development cycle and save costs.
It helps understand the developers the code base and enable them to make changes quickly.
Good unit tests serve as project documentation
Unit tests help with code re-use. Migrate both your code and your tests to your new project. Tweak the code till the tests run again.

MYTH:

It requires time, and I am always overscheduled
My code is rock solid! I do not need unit tests.

UNIT TEST != INTEGRATION TEST

UNIT TEST is easy to implement

Covers a single piece of code (usually an object or a function) tested the behavior without external resources

INTEGRATION TEST is complex to implement

demonstrate that different parts of a system work together in the real-life environment. They validate complex scenarios (we can think of integration tests as a user performing some high-level operation within our system), and usually require external resources, like databases or web servers, to be present

The kind of process testing

UNIT TEST PATTERN

The AAA Phrases

Arrange, Act, Assert

TDD and BDD

TDD

Test Driven Development

RULES:

You are not allowed to write any production code unless it is to make a failing unit test pass.
You are not allowed to write any more of a unit test than is sufficient to fail, and compilation failures are failures.
You are not allowed to write any more production code than is sufficient to pass the one failing unit test.

TDD

Uncle Bob

BDD

Behavior Driven Development

TDD == BDD

Testing Framework:

I picked JEST:

built-in assertion method
multi-environment, it can use in node and browser
can watch and run untested code or code changes only
built-in coverage

Example:

Terdapat dua array A[] dan B[] berisi angka integer

Buatlah fungsi untuk
melakukan check apakah array B adalah subarray dari array A!

Problems:

Write the test first


describe('#subArrayOf, when passed "A = [1, 2, 0, 5, 8, 1, 3] and B = [3, 0, 5, 1]"', () => {
  it('should returns true', () => {
    // Arrange
      
    
    // Act
    
      
    // Assert
    
    
  })

})

DEMO!

INTEGRATION TEST

We need to mock our data

Mocking framework:

Supertest
Pretender
Jest Mock (usually just mock function call)
Sinon
Test Double
Enzyme (for react)
React Test Renderer
Any suggestion