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JUnit is an open source framework for Java programming language which is used for writing and running tests. This practice helps developers to discover failures in their logic behind the code and improve the quality of their code. Also, JUnit testing can be used in order to guarantee that, the code will work as expected in case of future changes. We can integrate JUnit Framework with Eclipse, Ant and Maven.
Annotation is a predefined logic that is added java source code. Classes, methods, variables, parameters and packages may be annotated. JUnit uses annotations and works according to the annotation’s predefined logic.
JUnit framework works on following these annotations which are named as below:
1. @BeforeClass: This annotation will run once before any of the test methods in the class. This annotation neither provides any parameter nor returns any parameter. The @BeforeClass methods of superclasses will be run before those the current class.
2. @AfterClass: This annotation will run once after all the tests in the class have been run. All @AfterClass methods are guaranteed to run even if a BeforeClass method throws an exception. The @AfterClass methods declared in superclasses will be run after those of the current class. This annotation neither provides any parameter nor returns any parameter.
3. @Before: This annotation will run before each @Test. The @Before methods of super classes will be run before those of the current class. This annotation neither provides any parameter nor returns any parameter.
4. @After: This annotation will run after each @Test. The @After methods declared in super classes will be run after those of the current class. This annotation neither provides any parameter nor returns any parameter.
5. @Test: The Test annotation tells JUnit that this is the test that needs to be executed. Any exceptions thrown by the @Test will be reported by JUnit as a failure. If no exceptions are thrown, the test is assumed to have succeeded. This annotation uses optional parameters as expected, timeout and so on.
6. @Ignore: Sometimes you want to temporarily disable a test or a group of tests. Methods annotated with Test that are also annotated with @Ignore will not be executed as tests.
7. @RunWith: When a class is annotated with @RunWith or extends a class annotated with @RunWith, JUnit will invoke the class it references to run the tests in that class instead of the runner built into JUnit.
If you are not using JUnit and you want to temporarily disable a particular @Test which is partially implemented OR don’t want that @Test to fail while running a test methods, then you will be either comment that particular @Test or you will delete the @Test and the test runner class also not includes such @Test in report.
JUnit provides you an annotation to overcome this problem named as @Ignore. The @Ignore annotation can be used when you want temporarily disable the execution of a particular @test. Every method that is associated with @Ignore won’t be executed. Test runner class also includes such @Test in report.
@Ignore annotation can be used in two ways:
1. To ignore particular @Test
2. To ignore a Class
A class could have numbers of test methods and some of them might not be required in execution due to some reasons like partial implemented and so on, then we use @Ignore annotation to skip them.
Below is the example that a class has two @Test methods, one is with @Ignore annotation and second @Test is without @Ignore annotation.
After execution the JUnit result will look like this as displayed in below screenshot:
@Ignore can also be used with Class to skip the whole class means all the @Test methods inside a class will be skipped.
Below is the example, how to ignore all the tests in class:
After execution the JUnit result will look like this as displaying in below screenshot:
You can also pass string argument in @Ignore annotation. This is an optional parameter, using this string parameter you can show the reason why you have ignored the @Test or Class.
Below is the example, how to pass string parameter in @Ignore annotation:
But output will be same as above, the parameter string used in @Ignore annotation is not printed in JUnit output.
I do hope that this post helps you in understanding the core concept of JUnit. Let me know your thoughts on this via comments and I will get back to you as soon as possible. Adios for now