Why Test?

Behave the way the user expects.

• bug or functionality issues)
• be confident the calculations are correct

Helps define requirements of what you are looking to build.

• helps developers hone in and focus on what is necessary

Others can easily understand.

• convey the intent of the application clearly.
• tests also act as documentation.

Backend can have bugs that you will never find out about until something goes wrong

Easy to modify or extend, refactor

• applications are never static (new feature and functionality) - ensures consistency on change.
• address only what is necessary - getting to agreed test suite.

How to test

# Write a failing test (fail, stop)

# Write a success test (passing)
## functionality may not be complete, but working
null test → pass

stub required objects → test presence → pass

write functionality spec → test failure → create functionality in actual file → test → pass

Test Structure

Test structure should follow:

Setup
Method
Validation/Assertion

Boundaries

Avoid implementation of external dependencies in unit tests.

Using things like dependency injection (and shallow-mocking the dependencies), you can avoid relying on the actual implementations to run properly for the test to pass.

// external dependencies and its implementation tested
import (
  someExternalFunction
)

func testTightCoupling(someParam: string) boolean {
  testValue := someParam
  
  // calling actual implementation (bad)
  someExternalFunction(testValue);
  
  // assertion
}

// shallow dependencies using mock return value
const mockedServiceMethod = mock(someExternalFunction)

func testLooseCoupling() boolean {
  testValue := someParam
  
  // calling mocked implementation
  mockedServiceMethod(testValue)
}