Testing

Question 1

Types of testing?

Answer 1

Unit testing - functions/interfaces
System Testing -
Integration Testing

Question 2

@DisplayName

Answer 2

annotation to change name of the test in the left bottom corner of the IDE

Question 3

assertEquals

Answer 3

The assertEquals assertion verifies that the expected and the actual values are equal:

Question 4

assertArrayEquals

Answer 4

If we want to assert that two arrays are equals, we can use the assertArrayEquals:
@Test
public void whenAssertingArraysEquality_thenEqual() {
char[] expected = {‘J’,’u’,’n’,’i’,’t’};
char[] actual = “Junit”.toCharArray();

assertArrayEquals(expected, actual); }

Question 5

assertNotNull and assertNull

Answer 5

@Test
public void whenAssertingNull_thenTrue() {
Object car = null;

assertNull("The car should be null", car); } In the opposite way, if we want to assert that an object should not be null we can use the assertNotNull assertion.

Question 6

assertNotSame and assertSame

Answer 6

With assertNotSame, it’s possible to verify if two variables don’t refer to the same object:

@Test
public void whenAssertingNotSameObject_thenDifferent() {
    Object cat = new Object();
    Object dog = new Object();

assertNotSame(cat, dog); } Otherwise, when we want to verify that two variables refer to the same object, we can use the assertSame assertion.

Question 7

assertTrue and assertFalse

Answer 7

In case we want to verify that a certain condition is true or false, we can respectively use the assertTrue assertion or the assertFalse one:

@Test
public void whenAssertingConditions_thenVerified() {
assertTrue(“5 is greater then 4”, 5 > 4);
assertFalse(“5 is not greater then 6”, 5 > 6);
}

Question 8

fail

Answer 8

The fail assertion fails a test throwing an AssertionFailedError. It can be used to verify that an actual exception is thrown or when we want to make a test failing during its development.

Let’s see how we can use it in the first scenario:

@Test
public void whenCheckingExceptionMessage_thenEqual() {
try {
methodThatShouldThrowException();
fail(“Exception not thrown”);
} catch (UnsupportedOperationException e) {
assertEquals(“Operation Not Supported”, e.getMessage());
}
}

Question 9

assertThat

Answer 9

The assertThat assertion is the only one in JUnit 4 that has a reverse order of the parameters compared to the other assertions.

In this case, the assertion has an optional failure message, the actual value, and a Matcher object.
Let’s see how we can use this assertion to check if an array contains particular values:

@Test
public void testAssertThatHasItems() {
    assertThat(
      Arrays.asList("Java", "Kotlin", "Scala"), 
      hasItems("Java", "Kotlin"));
}

Question 10

assertAll

Answer 10

checks for multiple methods in the same time

Question 11

assertTimeout

Question 12

Difference between assertion and assumption

Answer 12

Assumption
met- Test runs
not met- Test gets aborted

Assertion
met- Test Succeeds
not met- Test fails

Question 13

@Nested

Answer 13

Will make the child class test get running when the we run the class test

Question 14

@Inject

Answer 14

Annotation used for junit 5 for DI

Question 15

@ExtendsWith

Answer 15

Will put it on top of the class in which we are going to perform our tests on and decorate it with

Question 16

How to Di in JUNIT?

Answer 16

Extending the ParameterResolverMethod and instantiating it