리액트 테스트 도구 - Jest

https://jestjs.io/

Jest

 

C:\Users\knew\Documents\20211104\jest-test>npm init
This utility will walk you through creating a package.json file.
It only covers the most common items, and tries to guess sensible defaults.

See `npm help init` for definitive documentation on these fields
and exactly what they do.

Use `npm install <pkg>` afterwards to install a package and
save it as a dependency in the package.json file.

Press ^C at any time to quit.
package name: (jest-test)
version: (1.0.0)
description:
entry point: (index.js)
test command: jest --watch
git repository:
keywords:
author:
license: (ISC)
About to write to C:\Users\knew\Documents\20211104\jest-test\package.json:

{
  "name": "jest-test",
  "version": "1.0.0",
  "description": "",
  "main": "index.js",
  "scripts": {
    "test": "jest --watch"
  },
  "author": "",
  "license": "ISC"
}


Is this OK? (yes)

C:\Users\knew\Documents\20211104\jest-test>npm install --save-dev jest

added 327 packages, and audited 328 packages in 3s

24 packages are looking for funding
  run `npm fund` for details

found 0 vulnerabilities

C:\Users\knew\Documents\20211104\jest-test>npm run test

> jest-test@1.0.0 test
> jest --watch
Determining test suites to run...
--watch is not supported without git/hg, please use --watchAll

C:\Users\knew\Documents\20211104\jest-test>npm run test

> jest-test@1.0.0 test
> jest --watchAll
No tests found, exiting with code 0

Watch Usage
 › Press f to run only failed tests.
 › Press o to only run tests related to changed files.
 › Press p to filter by a filename regex pattern.
 › Press t to filter by a test name regex pattern.
 › Press q to quit watch mode.
 › Press Enter to trigger a test run.

책과 다르게 --wacthAll 로 변경처리하니 정상적으로 된다.

 

index.js

const sum = (a,b) => {
   return a+b;
};

module.exports = {
   sum,
};

 

index.test.js

const { sum } = require('./index');

describe('test index.js file', () => {
	test('adds 1 + 2 to equal 3', () => {
	  expect(sum(1, 2)).toBe(3);
	});
});

 

다시 npm run test 하면

 

index.js 에서 + 를 * 변경하면

 

index.js

const sum = (a,b) => {
   return a+b;
};

const person = (name, age) => {
	return {
		name,
		age,
	};
};

const toggle = (a) => {
	return !a;
};

const range = (start, end) => {
	let result = [];
	for (let i = start; i <= end; i++){
		result.push(i);
	}
	return result;
};

module.exports = {
   sum,
   person,
   toggle,
   range,
};

 

index.test.js

const { sum, person, toggle, range } = require('./index');

describe('test index.js file', () => {
	test('adds 1 + 2 to equal 3', () => {
	  expect(sum(1, 2)).toBe(3);
	});
});

describe('test index.js file', () => {
	test('makes a person', () => {
	  expect(person('Kim', 20)).toEqual({
		name : 'Kim',
		age : 20,
	  });
	});
});

describe('test index.js file', () => {
	test('return false', () => {
	  expect(toggle(true)).toBeFalsy();
	  expect(toggle(true)).not.toBeTruthy();
	});
});

describe('test index.js file', () => {
	test('has 2', () => {
	  expect(range(1,3)).toContain(2);
	});
});

https://jestjs.io/docs/using-matchers

Using Matchers · Jest

 

---

npx jest --coverage

테스트 대상이 되는 소스 코드 중 테스트 코드를 통해 검증된 코드의 비율을 의미하며, 테스트 수행 결과를 정량적으로 나타내는 수치이다.

 

위 결과는 모두 테스트한경우

아래 결과는 테스트 마지막 한개를 주석처리한경우