@aminzer/describe-function-test

Simple helper for defining Jest tests for functions.

Usage example

Example function:

const formatGreeting = ({ personName }: { personName?: string } = {}): string => {
  if (personName) {
    return `Welcome, ${personName}!`;
  }

  return `Welcome!`;
};

export default formatGreeting;

Example test:

import { describeFunctionTest } from '@aminzer/describe-function-test';
import formatGreeting from './formatGreeting';

describeFunctionTest(formatGreeting, __filename, {
  testCases: [
    {
      description: 'when no arguments are passed',
      args: [],
      expectedResult: 'Welcome!',
    },
    {
      description: 'when person name is passed',
      args: [{ personName: 'Mike' }],
      expectedResult: 'Welcome, Mike!',
    },
  ],
});

API

describeFunctionTest

Overview

describeFunctionTest is used for defining a test for the provided function with predefined test cases. It's using native Jest describe function under the hood.

Import

import { describeFunctionTest } from '@aminzer/describe-function-test';

Parameters

• functionToTest (function, required) - function to be tested.
• testFilePath (string, required) - Path to the test file. __filename can be used here.
• options (object, required) - test settings.

options object accepts the following arguments:

• testCases (TestCase[], optional) - non-grouped test cases to be verified.
• testCaseGroups ({ description: string, testCases: TestCase[], only?: boolean }[], optional) - grouped test cases to be verified.
• prepareResult (function, optional) - function to format actual and expected test results before comparison. If not provided - the results are compared as is.
• beforeAll (function, optional) - function that's passed as an argument to Jest beforeAll call for all tests.
• afterAll (function, optional) - function that's passed as an argument to Jest afterAll call for all tests.

TestCase<Args extends unknown[], Result> type contains:

• description (string, optional) - test case description.
• args (Args, required) - array of arguments that are passed to the tested function in this test case.
• expectedResult (Result, required) - expected function call return value for the passed args.
• additionalAssertion (function, optional) - additional checks that need to be verified in this test case.
• only (boolean, optional) - if true - this test case is defined with Jest describe.only call.

Return value

void, nothing is returned.

formatTestName

Overview

formatTestName is used for generation of test name in format path > to > tested > file.

Import

import { formatTestName } from '@aminzer/describe-function-test';

Parameters

• testFilePath (string, required) - Path to the test file. __filename can be used here.

Return value

string - formatted test name.