How to use JUnit4TestAdapterCache class of junit.framework package

assertTrue will fail if the second parameter evaluates to false (in other words, it ensures that the value is true). assertFalse does the opposite.

assertTrue("This will succeed.", true);
assertTrue("This will fail!", false);

assertFalse("This will succeed.", false);
assertFalse("This will fail!", true);

As with many other things, the best way to become familiar with these methods is to just experiment :-).

Short answer
there's no way to parametrize class creation with JUnit 5 following the style of JUnit 4.

Fortunately, the very intention of separation test logic and test input data (parameters) can be implemented differently.

JUnit 5 has its own approach for making parameterized tests, and, of course, it is different from JUnit 4. The new approach does not allow to use parameterized fixtures at the class level, i.e. through its every test method. So every parameterized test method should be explicitly annotated with a link to parameters.

JUnit 5 provides a plenty of parameter source types, that could be found in documentation and guides

In your case, the simplest way to migrate from @Parameters of Junit 4 is using @MethodSource or @ArgumentsSource of org.junit.jupiter.params.provider.*.

JUnit 4:

@RunWith(Parameterized.class)
public class MyTestWithJunit4 {
    @Parameters
    public static Collection<Object[]> data() {
      return Arrays.asList(new Object[][] {     
               { 0, 0, 0 },
               { 1, 2, 3 }, 
               { 5, 3, 8 } 
      });
    }

    int first;
    int second;
    int sum;

    public MyTestWithJunit4(int first, int second, int sum) {
      this.first = first;
      this.second = second;
      this.sum = sum;
    }

    @Test
    public void test() {
      assertEquals(sum, first + second));
    }
}

JUnit 5 (with @MethodSource):

class MyTestWithJunit5 {

  @DisplayName("Test with @MethodSource")
  @ParameterizedTest(name = "{index}: ({0} + {1}) => {2})")
  @MethodSource("localParameters")
  void test(int first, int second, int sum) {
    assertEquals(sum, first + second);
  }

  static Stream<Arguments> localParameters() {
    return Stream.of(
        Arguments.of(0, 0, 0),
        Arguments.of(1, 2, 3),
        Arguments.of(5, 3, 8)
    );
  }
}

JUnit 5 (with @ArgumentsSource):

class MyTestWithJunit5 {
  @DisplayName("Test with @ArgumentsSource")
  @ParameterizedTest(name = "{index}: ({0} + {1}) => {2})")
  @ArgumentsSource(Params.class)
  void test(int first, int second, int sum) {
    assertEquals(sum, first + second);
  }

  static class Params implements ArgumentsProvider {
    @Override
    public Stream<? extends Arguments> provideArguments(ExtensionContext context) {
      return Stream.of(
          Arguments.of(0, 0, 0),
          Arguments.of(1, 2, 3),
          Arguments.of(5, 3, 8)
      );
    }
  }
}

Consider that a method in @MethodSource and a class in @ArgumentsSource could be described anywhere, not only inside the same class where the test methods are located. Also @MethodSource allows to provide multiple source methods, since its value is a String[].

Some remarks and comparison

In JUnit 4 we could only have a single factory method providing parameters, and the tests were supposed to be built around those parameters. On the contrary, JUnit 5 gives more abstraction and flexibility in binding parameters and decouples test logic from its parameters, which are secondary. That allows building tests independently from parameter sources, and easily change them when needed.

Dependency requirement

Parameterized tests feature is not included in the core junit-jupiter-engine, but is located in a separate dependency junit-jupiter-params.

By default Maven uses the following naming conventions when looking for tests to run:

• Test*
• *Test
• *Tests (has been added in Maven Surefire Plugin 2.20)
• *TestCase

If your test class doesn't follow these conventions you should rename it or configure Maven Surefire Plugin to use another pattern for test classes.

You will get this exception, if you use the JUnit 4.4 core runner to execute a class that has no "@Test" method. Kindly consult the link for more info.

courtesy vipin8169

The answer is now to create a @ClassRule within your suite. The rule will be invoked before or after (depending on how you implement it) each test class is run. There are a few different base classes you can extend/implement. What is nice about class rules is that if you do not implement them as anonymous classes then you can reuse the code!

Here is an article about them: http://java.dzone.com/articles/junit-49-class-and-suite-level-rules

Here is some sample code to illustrate their use. Yes, it is trivial, but it should illustrate the life-cycle well enough for you to get started.

First the suite definition:

import org.junit.*;
import org.junit.rules.ExternalResource;
import org.junit.runners.Suite;
import org.junit.runner.RunWith;


@RunWith( Suite.class )
@Suite.SuiteClasses( { 
    RuleTest.class,
} )
public class RuleSuite{

    private static int bCount = 0;
    private static int aCount = 0;

    @ClassRule
    public static ExternalResource testRule = new ExternalResource(){
            @Override
            protected void before() throws Throwable{
                System.err.println( "before test class: " + ++bCount );
                sss = "asdf";
            };

            @Override
            protected void after(){
                System.err.println( "after test class: " + ++aCount );
            };
        };


    public static String sss;
}

And now the test class definition:

import static org.junit.Assert.*;

import org.junit.ClassRule;
import org.junit.Rule;
import org.junit.Test;
import org.junit.rules.ExternalResource;

public class RuleTest {

    @Test
    public void asdf1(){
        assertNotNull( "A value should've been set by a rule.", RuleSuite.sss );
    }

    @Test
    public void asdf2(){
        assertEquals( "This value should be set by the rule.", "asdf", RuleSuite.sss );
    }
}

Epsilon is the value that the 2 numbers can be off by. So it will assert to true as long as Math.abs(expected - actual) <= epsilon

TL;DR; Unfortunately, there is no built-in solution yet (at time of writting, 2022), hence you are free to use and/or implement whatever fits your situation.

Example

An alternative is to use the CountDownLatch class.

public class DatabaseTest {

    /**
     * Data limit
     */
    private static final int DATA_LIMIT = 5;

    /**
     * Countdown latch
     */
    private CountDownLatch lock = new CountDownLatch(1);

    /**
     * Received data
     */
    private List<Data> receiveddata;

    @Test
    public void testDataRetrieval() throws Exception {
        Database db = new MockDatabaseImpl();
        db.getData(DATA_LIMIT, new DataCallback() {
            @Override
            public void onSuccess(List<Data> data) {
                receiveddata = data;
                lock.countDown();
            }
        });

        lock.await(2000, TimeUnit.MILLISECONDS);

        assertNotNull(receiveddata);
        assertEquals(DATA_LIMIT, receiveddata.size());
    }
}

NOTE you can't just used syncronized with a regular object as a lock, as fast callbacks can release the lock before the lock's wait method is called. See this blog post by Joe Walnes.

EDIT Removed syncronized blocks around CountDownLatch thanks to comments from @jtahlborn and @Ring

Declare following function within test class:

@Config(application = TestApp::class)
@RunWith(AndroidJUnit4::class)
@LooperMode(LooperMode.Mode.PAUSED)
class MyFragmentTest {

    private val createQuoteRecyclerViewAdapter: CreateQuoteRecyclerViewAdapter = mock()
    private val viewModel: MyViewModel = mock()

    private fun launchFragment(): FragmentScenario<MyFragment> {
      return launchFragmentInContainer(factory = object : FragmentFactory() {
        override fun instantiate(classLoader: ClassLoader, className: String): Fragment {
          return MyFragment().apply {
            createQuoteRecyclerViewAdapter = this@MyFragmentTest.createQuoteRecyclerViewAdapter
            viewModel = this@MyFragmentTest.viewModel
            // assign other deps here as per your needs
          }
        }
      }, themeResId = R.style.AppTheme)
    }

}

Where TestApp is declared as such:

    class TestApp : Application()

This might be needed in order to refrain from error, which will happen in your custom application class's onCreate() method, where Dagger tree is being constructed.

After having this setup you can start writing your unit test:

@Test
fun `navigation to login screen is correctly performed`() {
    val navController: NavController = mock()

    val scenario = launchFragment()
    scenario.onFragment {
        Navigation.setViewNavController(it.requireView(), navController)
    }

    onView(withId(R.id.button_login)).perform(click())
    verify(mockNavController).navigate(R.id.action_intro_fragment_to_login_fragment)
}

I've solved the problem without XmlAdapter's.

I've written JAXB-annotated objects for Map, Map.Entry and Collection.
The main idea is inside the method xmlizeNestedStructure(...):

Take a look at the code:

public final class Adapters {

private Adapters() {
}

public static Class<?>[] getXmlClasses() {
    return new Class<?>[]{
                XMap.class, XEntry.class, XCollection.class, XCount.class
            };
}

public static Object xmlizeNestedStructure(Object input) {
    if (input instanceof Map<?, ?>) {
        return xmlizeNestedMap((Map<?, ?>) input);
    }
    if (input instanceof Collection<?>) {
        return xmlizeNestedCollection((Collection<?>) input);
    }

    return input; // non-special object, return as is
}

public static XMap<?, ?> xmlizeNestedMap(Map<?, ?> input) {
    XMap<Object, Object> ret = new XMap<Object, Object>();

    for (Map.Entry<?, ?> e : input.entrySet()) {
        ret.add(xmlizeNestedStructure(e.getKey()),
                xmlizeNestedStructure(e.getValue()));
    }

    return ret;
}

public static XCollection<?> xmlizeNestedCollection(Collection<?> input) {
    XCollection<Object> ret = new XCollection<Object>();

    for (Object entry : input) {
        ret.add(xmlizeNestedStructure(entry));
    }

    return ret;
}

@XmlType
@XmlRootElement
public final static class XMap<K, V> {

    @XmlElementWrapper(name = "map")
    @XmlElement(name = "entry")
    private List<XEntry<K, V>> list = new LinkedList<XEntry<K, V>>();

    public XMap() {
    }

    public void add(K key, V value) {
        list.add(new XEntry<K, V>(key, value));
    }

}

@XmlType
@XmlRootElement
public final static class XEntry<K, V> {

    @XmlElement
    private K key;

    @XmlElement
    private V value;

    private XEntry() {
    }

    public XEntry(K key, V value) {
        this.key = key;
        this.value = value;
    }

}

@XmlType
@XmlRootElement
public final static class XCollection<V> {

    @XmlElementWrapper(name = "list")
    @XmlElement(name = "entry")
    private List<V> list = new LinkedList<V>();

    public XCollection() {
    }

    public void add(V obj) {
        list.add(obj);
    }

}

}

It works!

Let's look at a demo output:

<xMap>
    <map>
        <entry>
            <key xsi:type="xCount" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">
                <count>1</count>
                <content xsi:type="xs:string" xmlns:xs="http://www.w3.org/2001/XMLSchema">a</content>
            </key>
            <value xsi:type="xCollection" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">
                <list>
                    <entry xsi:type="xs:string" xmlns:xs="http://www.w3.org/2001/XMLSchema">a1</entry>
                    <entry xsi:type="xs:string" xmlns:xs="http://www.w3.org/2001/XMLSchema">a2</entry>
                    <entry xsi:type="xs:string" xmlns:xs="http://www.w3.org/2001/XMLSchema">a3</entry>
                </list>
            </value>
        </entry>
        <entry>
            <key xsi:type="xCount" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">
                <count>2</count>
                <content xsi:type="xs:string" xmlns:xs="http://www.w3.org/2001/XMLSchema">b</content>
            </key>
            <value xsi:type="xCollection" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">
                <list>
                    <entry xsi:type="xs:string" xmlns:xs="http://www.w3.org/2001/XMLSchema">b1</entry>
                    <entry xsi:type="xs:string" xmlns:xs="http://www.w3.org/2001/XMLSchema">b3</entry>
                    <entry xsi:type="xs:string" xmlns:xs="http://www.w3.org/2001/XMLSchema">b2</entry>
                </list>
            </value>
        </entry>
        <entry>
            <key xsi:type="xCount" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">
                <count>3</count>
                <content xsi:type="xs:string" xmlns:xs="http://www.w3.org/2001/XMLSchema">c</content>
            </key>
            <value xsi:type="xCollection" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">
                <list>
                    <entry xsi:type="xs:string" xmlns:xs="http://www.w3.org/2001/XMLSchema">c1</entry>
                    <entry xsi:type="xs:string" xmlns:xs="http://www.w3.org/2001/XMLSchema">c2</entry>
                    <entry xsi:type="xs:string" xmlns:xs="http://www.w3.org/2001/XMLSchema">c3</entry>
                </list>
            </value>
        </entry>
    </map>
</xMap>

Sorry, the demo output uses also a data structure called "count" which is not mentioned in the Adapter's source code.

BTW: does anyone know how to remove all these annoying and (in my case) unnecessary xsi:type attributes?