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How to use common JUnit annotations
Educative Answers Team
JUnit annotations are specialized syntactic meta-data used in Java to improve readability and code structure – they can be applied to variables, classes, methods, packages, and parameters.
Common Annotations
@Test
- Used to suggest that the following method is a test method.
- The method can’t have a return value.
- It shouldn’t be private or static.
- The method may declare parameters.
@Test(timeout = 50)
- This annotation is used to automatically stop tests from running after a set duration of time.
@ParametrizedTest
- It is used to run a test method multiple times with different parameters.
- It requires a source for the method argument, e.g., Value Source.
@RepeatedTest
- This annotation takes in value x: the number of times the test should be repeated.
@TestInstance
- JUnit creates an instance of each test class when using @Test. @TestInstance changes the method to ‘per-class’ as test instances are created once within a class.
@Nested
- By default, JUnit does not allow any nested classes in the test method, but @Nested does.
- Nested classes shouldn’t be static.
@BeforeEach
- This annotation implements the following method before performing each test.
- It may be used to set up preconditions for the test.
@AfterEach
- This annotation implements the following method after performing each test.
@BeforeAll
- This annotation implements the following method before performing any test.
@AfterAll
- This annotation implements the following method after performing any test.
@BeforeClass
- This annotation implements the following method before all the test cases within a class.
@AfterClass
- This annotation implements the following method after all the tests within a class.
@Disabled
- Rather than commenting out a test, use the @Disabled annotation to ensure that the test is not run in the following implementation.
Code
The code below suggests how different annotations can be used.
class HelloWorld {
@AfterTest
public static void a_t( String args[] ) {
System.out.println( "Run this after running Test!!" );
}
@AfterClass
public static void a_c( String args[] ) {
System.out.println( "Run this after running all Tests in a class!!" );
}
@Test
public static void _t( String args[] ) {
System.out.println( "Test method" );
}
@BeforeTest
public static void b_t( String args[] ) {
System.out.println( "Run this before running Test!!" );
}
@BeforeClass
public static void b_c( String args[] ) {
System.out.println( "Run this before running all Tests in a class!!" );
}
}Most of these annotations can be found in the
org.junit.jupiter.apipackage in thejunit-jupiter-apimodule.
RELATED TAGS
java
junit
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