Test Structure

Test should follow three steps:

Setup
Method
Validation/Assertion

Avoid Implementation of External Dependencies in Tests

You want to avoid external dependencies in test as much as possible.

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
  someExternalFunction(testValue);
  // assertion
}

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

func testLooseCoupling() boolean {
  testValue := someParam
}