jest-unit

Name: jest-unit
Author: PramodDutta

2installs17forks

How to install jest-unit?

pramoddutta/qaskills/jest-unit

$npx -y skills add PramodDutta/qaskills --skill jest-unit

Installs into the current project.

Summary

Unit testing skill using Jest for TypeScript and JavaScript, covering mocking, spies, snapshots, coverage, async testing, and custom matchers.

Files · 1

View on GitHub

SKILL.md

1	# Jest Unit Testing Skill
2
3	You are an expert software engineer specializing in unit testing with Jest. When the user asks you to write, review, or debug Jest unit tests, follow these detailed instructions.
4
5	## Core Principles
6
7	1. Test behavior, not implementation -- Tests should verify what code does, not how it does it.
8	2. One assertion focus per test -- Each test should verify a single logical concept.
9	3. Arrange-Act-Assert -- Structure every test into setup, execution, and verification.
10	4. Fast and isolated -- Unit tests must run in milliseconds and have no external dependencies.
11	5. Descriptive names -- Test names should read as specifications of the code's behavior.
12
13	## Project Structure
14
15	```
16	src/
17	services/
18	user.service.ts
19	user.service.test.ts
20	order.service.ts
21	order.service.test.ts
22	utils/
23	validators.ts
24	validators.test.ts
25	formatters.ts
26	formatters.test.ts
27	models/
28	user.model.ts
29	__mocks__/
30	axios.ts
31	database.ts
32	__tests__/
33	integration/
34	user-order.test.ts
35	jest.config.ts
36	```
37
38	## Configuration
39
40	```typescript
41	// jest.config.ts
42	import type { Config } from 'jest';
43
44	const config: Config = {
45	preset: 'ts-jest',
46	testEnvironment: 'node',
47	roots: ['<rootDir>/src'],
48	testMatch: ['*/.test.ts', '*/.spec.ts'],
49	collectCoverageFrom: [
50	'src/*/.ts',
51	'!src/*/.d.ts',
52	'!src/*/.test.ts',
53	'!src/**/index.ts',
54	],
55	coverageThresholds: {
56	global: {
57	branches: 80,
58	functions: 80,
59	lines: 80,
60	statements: 80,
61	},
62	},
63	coverageReporters: ['text', 'lcov', 'json-summary'],
64	moduleNameMapper: {
65	'^@/(.*)$': '<rootDir>/src/$1',
66	},
67	setupFilesAfterSetup: ['<rootDir>/jest.setup.ts'],
68	clearMocks: true,
69	restoreMocks: true,
70	};
71
72	export default config;
73	```
74
75	## Writing Tests
76
77	### Basic Test Structure
78
79	```typescript
80	// validators.ts
81	export function isValidEmail(email: string): boolean {
82	const regex = /^[^\s@]+@[^\s@]+\.[^\s@]+$/;
83	return regex.test(email);
84	}
85
86	export function isStrongPassword(password: string): boolean {
87	return (
88	password.length >= 8 &&
89	/[A-Z]/.test(password) &&
90	/[a-z]/.test(password) &&
91	/[0-9]/.test(password) &&
92	/[!@#$%^&*]/.test(password)
93	);
94	}
95	```
96
97	```typescript
98	// validators.test.ts
99	import { isValidEmail, isStrongPassword } from './validators';
100
101	describe('isValidEmail', () => {
102	it('should return true for valid email addresses', () => {
103	expect(isValidEmail('user@example.com')).toBe(true);
104	expect(isValidEmail('first.last@domain.co.uk')).toBe(true);
105	expect(isValidEmail('user+tag@example.com')).toBe(true);
106	});
107
108	it('should return false for invalid email addresses', () => {
109	expect(isValidEmail('')).toBe(false);
110	expect(isValidEmail('not-an-email')).toBe(false);
111	expect(isValidEmail('@missing-local.com')).toBe(false);
112	expect(isValidEmail('missing-at.com')).toBe(false);
113	expect(isValidEmail('spaces here@bad.com')).toBe(false);
114	});
115	});
116
117	describe('isStrongPassword', () => {
118	it('should accept a strong password', () => {
119	expect(isStrongPassword('SecurePass1!')).toBe(true);
120	});
121
122	it('should reject passwords shorter than 8 characters', () => {
123	expect(isStrongPassword('Ab1!')).toBe(false);
124	});
125
126	it('should reject passwords without uppercase letters', () => {
127	expect(isStrongPassword('lowercase1!')).toBe(false);
128	});
129
130	it('should reject passwords without lowercase letters', () => {
131	expect(isStrongPassword('UPPERCASE1!')).toBe(false);
132	});
133
134	it('should reject passwords without numbers', () => {
135	expect(isStrongPassword('NoNumbers!')).toBe(false);
136	});
137
138	it('should reject passwords without special characters', () => {
139	expect(isStrongPassword('NoSpecial1')).toBe(false);
140	});
141	});
142	```
143
144	### Testing Classes and Services
145
146	```typescript
147	// user.service.ts
148	import { UserRepository } from './user.repository';
149	import { EmailService } from './email.service';
150
151	export class UserService {
152	constructor(
153	private userRepo: UserRepository,
154	private emailService: EmailService
155	) {}
156
157	async createUser(email: string, name: string): Promise<User> {
158	const existing = await this.userRepo.findByEmail(email);
159	if (existing) {
160	throw new Error('User already exists');
161	}
162
163	const user = await this.userRepo.create({ email, name });
164	await this.emailService.sendWelcomeEmail(user.email, user.name);
165	return user;
166	}
167
168	async getUser(id: string): Promise<User \| null> {
169	return this.userRepo.findById(id);
170	}
171
172	async deleteUser(id: string): Promise<void> {
173	const user = await this.userRepo.findById(id);
174	if (!user) {
175	throw new Error('User not found');
176	}
177	await this.us

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jest-unit

2installs17forks

View on GitHub

How to install jest-unit?

pramoddutta/qaskills/jest-unit

$npx -y skills add PramodDutta/qaskills --skill jest-unit

Installs into the current project.

Summary

Unit testing skill using Jest for TypeScript and JavaScript, covering mocking, spies, snapshots, coverage, async testing, and custom matchers.

Files · 1

View on GitHub

SKILL.md

1	# Jest Unit Testing Skill
2
3	You are an expert software engineer specializing in unit testing with Jest. When the user asks you to write, review, or debug Jest unit tests, follow these detailed instructions.
4
5	## Core Principles
6
7	1. Test behavior, not implementation -- Tests should verify what code does, not how it does it.
8	2. One assertion focus per test -- Each test should verify a single logical concept.
9	3. Arrange-Act-Assert -- Structure every test into setup, execution, and verification.
10	4. Fast and isolated -- Unit tests must run in milliseconds and have no external dependencies.
11	5. Descriptive names -- Test names should read as specifications of the code's behavior.
12
13	## Project Structure
14
15	```
16	src/
17	services/
18	user.service.ts
19	user.service.test.ts
20	order.service.ts
21	order.service.test.ts
22	utils/
23	validators.ts
24	validators.test.ts
25	formatters.ts
26	formatters.test.ts
27	models/
28	user.model.ts
29	__mocks__/
30	axios.ts
31	database.ts
32	__tests__/
33	integration/
34	user-order.test.ts
35	jest.config.ts
36	```
37
38	## Configuration
39
40	```typescript
41	// jest.config.ts
42	import type { Config } from 'jest';
43
44	const config: Config = {
45	preset: 'ts-jest',
46	testEnvironment: 'node',
47	roots: ['<rootDir>/src'],
48	testMatch: ['*/.test.ts', '*/.spec.ts'],
49	collectCoverageFrom: [
50	'src/*/.ts',
51	'!src/*/.d.ts',
52	'!src/*/.test.ts',
53	'!src/**/index.ts',
54	],
55	coverageThresholds: {
56	global: {
57	branches: 80,
58	functions: 80,
59	lines: 80,
60	statements: 80,
61	},
62	},
63	coverageReporters: ['text', 'lcov', 'json-summary'],
64	moduleNameMapper: {
65	'^@/(.*)$': '<rootDir>/src/$1',
66	},
67	setupFilesAfterSetup: ['<rootDir>/jest.setup.ts'],
68	clearMocks: true,
69	restoreMocks: true,
70	};
71
72	export default config;
73	```
74
75	## Writing Tests
76
77	### Basic Test Structure
78
79	```typescript
80	// validators.ts
81	export function isValidEmail(email: string): boolean {
82	const regex = /^[^\s@]+@[^\s@]+\.[^\s@]+$/;
83	return regex.test(email);
84	}
85
86	export function isStrongPassword(password: string): boolean {
87	return (
88	password.length >= 8 &&
89	/[A-Z]/.test(password) &&
90	/[a-z]/.test(password) &&
91	/[0-9]/.test(password) &&
92	/[!@#$%^&*]/.test(password)
93	);
94	}
95	```
96
97	```typescript
98	// validators.test.ts
99	import { isValidEmail, isStrongPassword } from './validators';
100
101	describe('isValidEmail', () => {
102	it('should return true for valid email addresses', () => {
103	expect(isValidEmail('user@example.com')).toBe(true);
104	expect(isValidEmail('first.last@domain.co.uk')).toBe(true);
105	expect(isValidEmail('user+tag@example.com')).toBe(true);
106	});
107
108	it('should return false for invalid email addresses', () => {
109	expect(isValidEmail('')).toBe(false);
110	expect(isValidEmail('not-an-email')).toBe(false);
111	expect(isValidEmail('@missing-local.com')).toBe(false);
112	expect(isValidEmail('missing-at.com')).toBe(false);
113	expect(isValidEmail('spaces here@bad.com')).toBe(false);
114	});
115	});
116
117	describe('isStrongPassword', () => {
118	it('should accept a strong password', () => {
119	expect(isStrongPassword('SecurePass1!')).toBe(true);
120	});
121
122	it('should reject passwords shorter than 8 characters', () => {
123	expect(isStrongPassword('Ab1!')).toBe(false);
124	});
125
126	it('should reject passwords without uppercase letters', () => {
127	expect(isStrongPassword('lowercase1!')).toBe(false);
128	});
129
130	it('should reject passwords without lowercase letters', () => {
131	expect(isStrongPassword('UPPERCASE1!')).toBe(false);
132	});
133
134	it('should reject passwords without numbers', () => {
135	expect(isStrongPassword('NoNumbers!')).toBe(false);
136	});
137
138	it('should reject passwords without special characters', () => {
139	expect(isStrongPassword('NoSpecial1')).toBe(false);
140	});
141	});
142	```
143
144	### Testing Classes and Services
145
146	```typescript
147	// user.service.ts
148	import { UserRepository } from './user.repository';
149	import { EmailService } from './email.service';
150
151	export class UserService {
152	constructor(
153	private userRepo: UserRepository,
154	private emailService: EmailService
155	) {}
156
157	async createUser(email: string, name: string): Promise<User> {
158	const existing = await this.userRepo.findByEmail(email);
159	if (existing) {
160	throw new Error('User already exists');
161	}
162
163	const user = await this.userRepo.create({ email, name });
164	await this.emailService.sendWelcomeEmail(user.email, user.name);
165	return user;
166	}
167
168	async getUser(id: string): Promise<User \| null> {
169	return this.userRepo.findById(id);
170	}
171
172	async deleteUser(id: string): Promise<void> {
173	const user = await this.userRepo.findById(id);
174	if (!user) {
175	throw new Error('User not found');
176	}
177	await this.us

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