public class OutputFileTest {
    private File output; 
    @Before 
    public void createOutputFile() { 
       output = new File(...);
    }
  
true@After 
    public void deleteOutputFile() {
        output.delete(); 
    } 
    
    @Test 
    public void testFile1() {
       // code for test case objective
    } 
true@Test 
    public void testFile2() {
       // code for test case objective
    }
}

public class Test {                
truepublic static void main(String[] args) {        
truetrueResult result = JUnitCore.runClasses(CreateAndSetName.class);
        for (Failure failure : result.getFailures()) {
            System.out.println(failure.toString());                    
         }        
          System.out.println(result.wasSuccessful());                    
       }        
}      

package guru99.junit;        

import org.junit.Assert;        
import org.junit.Rule;        
import org.junit.Test;        
import org.junit.rules.ErrorCollector;        

public class ErrorCollectorExample {                
    @Rule        
    public ErrorCollector collector = new ErrorCollector();                        
    @Test        
    public void example() {                    
    collector.addError(new Throwable("There is an error in first line"));        
    collector.addError(new Throwable("There is an error in second line"));
        System.out.println("Hello");                    
        try {            
            Assert.assertTrue("A " == "B");                    
        } catch (Throwable t) {                    
            collector.addError(t);                    
        }        
        System.out.println("World!!!!");                    
    }        
}

import static java.time.Duration.ofMillis;
import static java.time.Duration.ofMinutes;
import static org.junit.jupiter.api.Assertions.assertAll;
import static org.junit.jupiter.api.Assertions.assertEquals;
import static org.junit.jupiter.api.Assertions.assertNotNull;
import static org.junit.jupiter.api.Assertions.assertThrows;
import static org.junit.jupiter.api.Assertions.assertTimeout;
import static org.junit.jupiter.api.Assertions.assertTimeoutPreemptively;
import static org.junit.jupiter.api.Assertions.assertTrue;

import java.util.concurrent.CountDownLatch;

import example.domain.Person;
import example.util.Calculator;

import org.junit.jupiter.api.Test;

class AssertionsDemo {

    private final Calculator calculator = new Calculator();

    private final Person person = new Person("Jane", "Doe");

    @Test
    void standardAssertions() {
        assertEquals(2, calculator.add(1, 1));
        assertEquals(4, calculator.multiply(2, 2),
                "The optional failure message is now the last parameter");
        assertTrue('a' < 'b', () -> "Assertion messages can be lazily evaluated -- "
                + "to avoid constructing complex messages unnecessarily.");
    }

    @Test
    void groupedAssertions() {
        // In a grouped assertion all assertions are executed, and all
        // failures will be reported together.
        assertAll("person",
            () -> assertEquals("Jane", person.getFirstName()),
            () -> assertEquals("Doe", person.getLastName())
        );
    }

    @Test
    void dependentAssertions() {
        // Within a code block, if an assertion fails the
        // subsequent code in the same block will be skipped.
        assertAll("properties",
            () -> {
                String firstName = person.getFirstName();
                assertNotNull(firstName);

                // Executed only if the previous assertion is valid.
                assertAll("first name",
                    () -> assertTrue(firstName.startsWith("J")),
                    () -> assertTrue(firstName.endsWith("e"))
                );
            },
            () -> {
                // Grouped assertion, so processed independently
                // of results of first name assertions.
                String lastName = person.getLastName();
                assertNotNull(lastName);

                // Executed only if the previous assertion is valid.
                assertAll("last name",
                    () -> assertTrue(lastName.startsWith("D")),
                    () -> assertTrue(lastName.endsWith("e"))
                );
            }
        );
    }

    @Test
    void exceptionTesting() {
        Exception exception = assertThrows(ArithmeticException.class, () ->
            calculator.divide(1, 0));
        assertEquals("/ by zero", exception.getMessage());
    }

    @Test
    void timeoutNotExceeded() {
        // The following assertion succeeds.
        assertTimeout(ofMinutes(2), () -> {
            // Perform task that takes less than 2 minutes.
        });
    }

    @Test
    void timeoutNotExceededWithResult() {
        // The following assertion succeeds, and returns the supplied object.
        String actualResult = assertTimeout(ofMinutes(2), () -> {
            return "a result";
        });
        assertEquals("a result", actualResult);
    }

    @Test
    void timeoutNotExceededWithMethod() {
        // The following assertion invokes a method reference and returns an object.
        String actualGreeting = assertTimeout(ofMinutes(2), AssertionsDemo::greeting);
        assertEquals("Hello, World!", actualGreeting);
    }

    @Test
    void timeoutExceeded() {
        // The following assertion fails with an error message similar to:
        // execution exceeded timeout of 10 ms by 91 ms
        assertTimeout(ofMillis(10), () -> {
            // Simulate task that takes more than 10 ms.
            Thread.sleep(100);
        });
    }

    @Test
    void timeoutExceededWithPreemptiveTermination() {
        // The following assertion fails with an error message similar to:
        // execution timed out after 10 ms
        assertTimeoutPreemptively(ofMillis(10), () -> {
            // Simulate task that takes more than 10 ms.
            new CountDownLatch(1).await();
        });
    }

    private static String greeting() {
        return "Hello, World!";
    }

}

import static org.junit.jupiter.api.Assertions.assertEquals;
import static org.junit.jupiter.api.Assumptions.assumeTrue;
import static org.junit.jupiter.api.Assumptions.assumingThat;

import example.util.Calculator;

import org.junit.jupiter.api.Test;

class AssumptionsDemo {

    private final Calculator calculator = new Calculator();

    @Test
    void testOnlyOnCiServer() {
        assumeTrue("CI".equals(System.getenv("ENV")));
        // remainder of test
    }

    @Test
    void testOnlyOnDeveloperWorkstation() {
        assumeTrue("DEV".equals(System.getenv("ENV")),
            () -> "Aborting test: not on developer workstation");
        // remainder of test
    }

    @Test
    void testInAllEnvironments() {
        assumingThat("CI".equals(System.getenv("ENV")),
            () -> {
                // perform these assertions only on the CI server
                assertEquals(2, calculator.divide(4, 2));
            });

        // perform these assertions in all environments
        assertEquals(42, calculator.multiply(6, 7));
    }

}