Apply '@Rule' after each '@Test' and before each '@After' in JUnit

Question

asked Jul 27, 2019 in DevOps and Agile by Han Zhyang (19.7k points)

I have a test suite where I am logging out of the system in @After and closing the browser in @AfterClass. I am trying to use @Rule to take a failed test screenshot using Selenium for every test method. I checked manually that @Rule only runs before every @Before but I want to set it up after @Test and before @After. I couldn't find out a simple solution. Any help will be appreciated.

public class MorgatgeCalculatorTest {
@Before
public void before(){
System.out.println("I am before");
}
@BeforeClass
public static void beforeclass(){
System.out.println("I am beforeclass");
}
@Test
public void test(){
System.out.println("I am Test");
}
@Test
public void test2(){
System.out.println("I am Test2");
}
@After
public void after(){
System.out.println("I am after");
}
@AfterClass
public static void afterclass(){
System.out.println("I am afterclass");
}
@Rule
ExpensiveExternalResource ExpensiveExternalResource = new ExpensiveExternalResource();
static class ExpensiveExternalResource implements MethodRule {
public ExpensiveExternalResource(){
System.out.println("I am rule");
}
@Override
public Statement apply(Statement arg0, FrameworkMethod arg1, Object arg2) {
// TODO Auto-generated method stub
return null;
}
}

The output I am getting is

I am beforeclass
I am rule
I am befor
I am Test
I am after
I am rule
I am before
I am Test2
I am after
I am afterclass

1 Answer

Prabhpreet Kaur · Answer 1 · 2019-07-27T12:56:00+0000

Because of the way that rules are set up, you can't have a rule that comes after @before or before @after. You can think of rules like shells that you put on the test method. The first shell to go on is @before/@after. Thereafter the @rules are applied.

A quick way to do what you want to do is to avoid @After altogether. A rule can be created so that it will take a screenshot if a method fails and then execute yours after the code. It isn't quite as pretty as @After, but it works. (also I implemented TestRule because MethodRule has been depreciated).

public class MortgageCalculatorTest {
    @Before
    public void before(){
        System.out.println("I am before");
    }

    @BeforeClass
    public static void beforeclass(){
        System.out.println("I am beforeclass");
    }

    @Test
    public void test(){
        System.out.println("I am a Test");
    }

    @Test
    public void test2(){
        System.out.println("I am a Failed Test");
        fail();
    }

    @AfterClass
            public static void afterclass(){
                System.out.println("I am afterclass");

    }

    @Rule
    public ExpensiveExternalResource ExpensiveExternalResource = new ExpensiveExternalResource();

    public static class ExpensiveExternalResource implements TestRule {

      // public ExpensiveExternalResource(){}

        public class ExpansiveExternalResourceStatement extends Statement{

            private Statement baseStatement;

            public ExpansiveExternalResourceStatement(Statement b){
                baseStatement = b;
            }

            @Override
            public void evaluate() throws Throwable {
                try{
                    baseStatement.evaluate();
                }catch(Error e){
                    System.out.println("I take a Screenshot");
                    throw e;
                }finally{
                    after();
                }
            }

            //Put your after code in this method!
            public void after(){
                System.out.println("I am after");
            }
        }

        public Statement apply(Statement base, Description description) {
            return new ExpansiveExternalResourceStatement(base);
        }
    }
}

All the work of the rule is done in a statement. A org.junit.runners.model. The statement is a class that represents a bundle of code. So here the apply method receives the bundle of code that you are putting a shell around. Apply returns your statement that executes the bundle of code that you gave it and surrounds it with a try/catch statement to catch the method failures.

The output for this method is:

I am beforeclass
I am before
I am a Test
I am after
I am before
I am a Failed Test
I take a Screenshot
I am after
I am afterclass

Apply '@Rule' after each '@Test' and before each '@After' in JUnit

1 Answer

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