Unit testing

IT1901 Fall 2021 - 8th Lecture

Testing

Testing

  • is an important part of software development

  • a way to ensure software quality

  • automated testing allows to develop new features with a minimal effort to check if the software still works as expected

  • testing frameworks

Testing (2)

  • design

  • implement

  • write automated tests

  • run tests

  • we do not test just for know, we write tests to keep running them during project life cycle

Testing (3)

  • design tests

  • implement the test

  • provide inputs

  • run the tests

  • provide expected outputs

  • check if the result we get matches what we expect

  • produce a manageable output that the developer can consult

Testing (3)

  • design tests

  • implement the test

  • provide inputs

  • run the tests

  • provide expected outputs

  • check if the result we get matches what we expect

  • produce a manageable output that the developer can consult

JUnit

JUnit

  • Is a Java unit testing framework.

  • provides the means to automate test

  • allows to eliminate redundant testing tasks

JUnit 4

import org.junit.*;

public class FoobarTest {
    @BeforeClass
    public static void setUpClass() throws Exception {
        // Code executed before the first test method
    }

    @Before
    public void setUp() throws Exception {
        // Code executed before each test
    }

    @Test
    public void testOneThing() {
        // Code that tests one thing
    }

    @Test
    public void testAnotherThing() {
        // Code that tests another thing
    }

    @Test
    public void testSomethingElse() {
        // Code that tests something else
    }

    @After
    public void tearDown() throws Exception {
        // Code executed after each test
    }

    @AfterClass
    public static void tearDownClass() throws Exception {
        // Code executed after the last test method
    }
}

https://en.wikipedia.org/wiki/JUnit

JUnit 5

import org.junit.jupiter.api.*;

public class FoobarTest {
    @BeforeAll
    public static void setUpClass() throws Exception {
        // Code executed before the first test method
    }

    @BeforeEach
    public void setUp() throws Exception {
        // Code executed before each test
    }

    @Test
    public void testOneThing() {
        // Code that tests one thing
    }

    @Test
    public void testAnotherThing() {
        // Code that tests another thing
    }

    @Test
    public void testSomethingElse() {
        // Code that tests something else
    }

    @AfterEach
    public void tearDown() throws Exception {
        // Code executed after each test
    }

    @AfterAll
    public static void tearDownClass() throws Exception {
        // Code executed after the last test method
    }
}

JUnit 4 vs JUnit 5

ElementJUnit 4JUnit 5

package

org.junit.*

org.junit.jupiter.api.*

code before first test

@BeforeClass

@BeforeAll

code before each test

@Before

@BeforeEach

test

@Test

@Test

code after each test

@After

@AfterEach

code after last test

@AfterClass

@AfterAll

JUnit 4 vs JUnit 5 (2)

ElementJUnit 4JUnit 5

ignoring test

@Ignore

@Disabled

assertions statically accessed with

Assert.assert…​

Assertions.assert…​

assertion messsage position

in the beginning of argument list

in the end of argument list

Expecting exceptions (1)

@Test
void testAssertingExpectedException() {
	Assertions.assertThrows(<ExpectedException.class>, () -> {
	    <code expected to throw exception>;
		});
}

Expecting exceptions (2)

  • if the code throws

    • the exception class that is expected the the test will PASS

    • a descendent class exception that is expected the the test will PASS

    • a different exception type the test will FAIL

    • throws no exception the test will FAIL

Testing in todo-list example

Norwegian University of Science and Technology