junit-5-skill

Name: junit-5-skill
Author: LambdaTest

335stars67forks

How to install junit-5-skill?

lambdatest/agent-skills/junit-5-skill

$npx -y skills add LambdaTest/agent-skills --skill junit-5-skill

Installs into the current project.

Summary

Generates production-grade JUnit 5 unit and integration tests in Java. Covers assertions, parameterized tests, lifecycle hooks, mocking with Mockito, and nested tests. Use when user mentions "JUnit", "JUnit 5", "@Test", "assertEquals", "Assertions", "Java unit test". Triggers on:

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SKILL.md

1	# JUnit 5 Testing Skill
2
3	You are a senior Java developer specializing in JUnit 5 testing.
4
5	## Step 1 — Test Type
6
7	```
8	├─ "unit test", "assert" → Standard unit test
9	├─ "parameterized", "multiple inputs" → @ParameterizedTest
10	├─ "mock", "Mockito" → Unit test with Mockito
11	├─ "integration test", "Spring" → Read reference/spring-integration.md
12	└─ Default → Standard unit test
13	```
14
15	## Core Patterns
16
17	### Basic Test
18
19	```java
20	import org.junit.jupiter.api.*;
21	import static org.junit.jupiter.api.Assertions.*;
22
23	class CalculatorTest {
24	private Calculator calculator;
25
26	@BeforeEach
27	void setUp() {
28	calculator = new Calculator();
29	}
30
31	@Test
32	@DisplayName("Addition of two positive numbers")
33	void addPositiveNumbers() {
34	assertEquals(5, calculator.add(2, 3));
35	}
36
37	@Test
38	void divideByZero_throwsException() {
39	assertThrows(ArithmeticException.class, () -> calculator.divide(10, 0));
40	}
41
42	@Test
43	void multipleAssertions() {
44	assertAll("calculator operations",
45	() -> assertEquals(4, calculator.add(2, 2)),
46	() -> assertEquals(0, calculator.subtract(2, 2)),
47	() -> assertEquals(6, calculator.multiply(2, 3))
48	);
49	}
50	}
51	```
52
53	### Assertions Reference
54
55	```java
56	assertEquals(expected, actual);
57	assertNotEquals(unexpected, actual);
58	assertTrue(condition);
59	assertFalse(condition);
60	assertNull(object);
61	assertNotNull(object);
62	assertThrows(IllegalArgumentException.class, () -> service.process(null));
63	assertTimeout(Duration.ofSeconds(2), () -> service.longRunningOp());
64	assertAll("group",
65	() -> assertNotNull(user.getName()),
66	() -> assertTrue(user.getAge() > 0)
67	);
68	assertIterableEquals(List.of(1, 2, 3), actualList);
69	```
70
71	### Parameterized Tests
72
73	```java
74	@ParameterizedTest
75	@ValueSource(strings = {"hello", "world", "junit"})
76	void stringIsNotEmpty(String value) {
77	assertFalse(value.isEmpty());
78	}
79
80	@ParameterizedTest
81	@CsvSource({"1,1,2", "2,3,5", "10,-5,5"})
82	void addNumbers(int a, int b, int expected) {
83	assertEquals(expected, calculator.add(a, b));
84	}
85
86	@ParameterizedTest
87	@MethodSource("provideUsers")
88	void validateUser(String name, int age, boolean expected) {
89	assertEquals(expected, validator.isValid(name, age));
90	}
91
92	static Stream<Arguments> provideUsers() {
93	return Stream.of(
94	Arguments.of("Alice", 25, true),
95	Arguments.of("", 25, false),
96	Arguments.of("Bob", -1, false)
97	);
98	}
99
100	@ParameterizedTest
101	@NullAndEmptySource
102	@ValueSource(strings = {" ", "\t"})
103	void blankStringsAreInvalid(String input) {
104	assertFalse(validator.isValid(input));
105	}
106	```
107
108	### Mocking with Mockito
109
110	```java
111	@ExtendWith(MockitoExtension.class)
112	class UserServiceTest {
113	@Mock private UserRepository userRepo;
114	@Mock private EmailService emailService;
115	@InjectMocks private UserService userService;
116
117	@Test
118	void createUser_savesAndSendsEmail() {
119	User user = new User("alice@test.com", "Alice");
120	when(userRepo.save(any(User.class))).thenReturn(user);
121
122	User result = userService.createUser("alice@test.com", "Alice");
123
124	assertNotNull(result);
125	verify(userRepo).save(any(User.class));
126	verify(emailService).sendWelcomeEmail("alice@test.com");
127	}
128
129	@Test
130	void getUser_notFound_throwsException() {
131	when(userRepo.findById(99L)).thenReturn(Optional.empty());
132	assertThrows(UserNotFoundException.class, () -> userService.getUser(99L));
133	}
134	}
135	```
136
137	### Nested Tests
138
139	```java
140	@DisplayName("UserService")
141	class UserServiceTest {
142	@Nested
143	@DisplayName("when creating a user")
144	class CreateUser {
145	@Test void withValidData_succeeds() { }
146	@Test void withDuplicateEmail_throwsException() { }
147	}
148
149	@Nested
150	@DisplayName("when deleting a user")
151	class DeleteUser {
152	@Test void existingUser_removesFromDb() { }
153	@Test void nonExistentUser_throwsException() { }
154	}
155	}
156	```
157
158	### Anti-Patterns
159
160	\| Bad \| Good \| Why \|
161	\|-----\|------\|-----\|
162	\| `@Test public void test1()` \| `@Test void shouldCalculateSum()` \| Descriptive names \|
163	\| Testing private methods \| Test via public API \| Implementation detail \|
164	\| No @DisplayName \| Always add display names \| Better reporting \|
165	\| `assertEquals(true, x)` \| `assertTrue(x)` \| More readable \|
166
167	## Maven Dependencies
168
169	```xml
170	<dependency>
171	<groupId>org.junit.jupiter</groupId>
172	<artifactId>junit-jupiter</artifactId>
173	<version>5.11.0</version>
174	<scope>test</scope>
175	</dependency>
176	<dependency>
177	<groupId>org.mockito</groupI

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junit-5-skill

335stars67forks

View on GitHub

How to install junit-5-skill?

lambdatest/agent-skills/junit-5-skill

$npx -y skills add LambdaTest/agent-skills --skill junit-5-skill

Installs into the current project.

Summary

Files · 1

View on GitHub

SKILL.md

1	# JUnit 5 Testing Skill
2
3	You are a senior Java developer specializing in JUnit 5 testing.
4
5	## Step 1 — Test Type
6
7	```
8	├─ "unit test", "assert" → Standard unit test
9	├─ "parameterized", "multiple inputs" → @ParameterizedTest
10	├─ "mock", "Mockito" → Unit test with Mockito
11	├─ "integration test", "Spring" → Read reference/spring-integration.md
12	└─ Default → Standard unit test
13	```
14
15	## Core Patterns
16
17	### Basic Test
18
19	```java
20	import org.junit.jupiter.api.*;
21	import static org.junit.jupiter.api.Assertions.*;
22
23	class CalculatorTest {
24	private Calculator calculator;
25
26	@BeforeEach
27	void setUp() {
28	calculator = new Calculator();
29	}
30
31	@Test
32	@DisplayName("Addition of two positive numbers")
33	void addPositiveNumbers() {
34	assertEquals(5, calculator.add(2, 3));
35	}
36
37	@Test
38	void divideByZero_throwsException() {
39	assertThrows(ArithmeticException.class, () -> calculator.divide(10, 0));
40	}
41
42	@Test
43	void multipleAssertions() {
44	assertAll("calculator operations",
45	() -> assertEquals(4, calculator.add(2, 2)),
46	() -> assertEquals(0, calculator.subtract(2, 2)),
47	() -> assertEquals(6, calculator.multiply(2, 3))
48	);
49	}
50	}
51	```
52
53	### Assertions Reference
54
55	```java
56	assertEquals(expected, actual);
57	assertNotEquals(unexpected, actual);
58	assertTrue(condition);
59	assertFalse(condition);
60	assertNull(object);
61	assertNotNull(object);
62	assertThrows(IllegalArgumentException.class, () -> service.process(null));
63	assertTimeout(Duration.ofSeconds(2), () -> service.longRunningOp());
64	assertAll("group",
65	() -> assertNotNull(user.getName()),
66	() -> assertTrue(user.getAge() > 0)
67	);
68	assertIterableEquals(List.of(1, 2, 3), actualList);
69	```
70
71	### Parameterized Tests
72
73	```java
74	@ParameterizedTest
75	@ValueSource(strings = {"hello", "world", "junit"})
76	void stringIsNotEmpty(String value) {
77	assertFalse(value.isEmpty());
78	}
79
80	@ParameterizedTest
81	@CsvSource({"1,1,2", "2,3,5", "10,-5,5"})
82	void addNumbers(int a, int b, int expected) {
83	assertEquals(expected, calculator.add(a, b));
84	}
85
86	@ParameterizedTest
87	@MethodSource("provideUsers")
88	void validateUser(String name, int age, boolean expected) {
89	assertEquals(expected, validator.isValid(name, age));
90	}
91
92	static Stream<Arguments> provideUsers() {
93	return Stream.of(
94	Arguments.of("Alice", 25, true),
95	Arguments.of("", 25, false),
96	Arguments.of("Bob", -1, false)
97	);
98	}
99
100	@ParameterizedTest
101	@NullAndEmptySource
102	@ValueSource(strings = {" ", "\t"})
103	void blankStringsAreInvalid(String input) {
104	assertFalse(validator.isValid(input));
105	}
106	```
107
108	### Mocking with Mockito
109
110	```java
111	@ExtendWith(MockitoExtension.class)
112	class UserServiceTest {
113	@Mock private UserRepository userRepo;
114	@Mock private EmailService emailService;
115	@InjectMocks private UserService userService;
116
117	@Test
118	void createUser_savesAndSendsEmail() {
119	User user = new User("alice@test.com", "Alice");
120	when(userRepo.save(any(User.class))).thenReturn(user);
121
122	User result = userService.createUser("alice@test.com", "Alice");
123
124	assertNotNull(result);
125	verify(userRepo).save(any(User.class));
126	verify(emailService).sendWelcomeEmail("alice@test.com");
127	}
128
129	@Test
130	void getUser_notFound_throwsException() {
131	when(userRepo.findById(99L)).thenReturn(Optional.empty());
132	assertThrows(UserNotFoundException.class, () -> userService.getUser(99L));
133	}
134	}
135	```
136
137	### Nested Tests
138
139	```java
140	@DisplayName("UserService")
141	class UserServiceTest {
142	@Nested
143	@DisplayName("when creating a user")
144	class CreateUser {
145	@Test void withValidData_succeeds() { }
146	@Test void withDuplicateEmail_throwsException() { }
147	}
148
149	@Nested
150	@DisplayName("when deleting a user")
151	class DeleteUser {
152	@Test void existingUser_removesFromDb() { }
153	@Test void nonExistentUser_throwsException() { }
154	}
155	}
156	```
157
158	### Anti-Patterns
159
160	\| Bad \| Good \| Why \|
161	\|-----\|------\|-----\|
162	\| `@Test public void test1()` \| `@Test void shouldCalculateSum()` \| Descriptive names \|
163	\| Testing private methods \| Test via public API \| Implementation detail \|
164	\| No @DisplayName \| Always add display names \| Better reporting \|
165	\| `assertEquals(true, x)` \| `assertTrue(x)` \| More readable \|
166
167	## Maven Dependencies
168
169	```xml
170	<dependency>
171	<groupId>org.junit.jupiter</groupId>
172	<artifactId>junit-jupiter</artifactId>
173	<version>5.11.0</version>
174	<scope>test</scope>
175	</dependency>
176	<dependency>
177	<groupId>org.mockito</groupI

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