Changing names of parameterized tests

Question

Is there a way to set my own custom test case names when using parameterized tests in JUnit4?

I'd like to change the default — [Test class].runTest[n] — to something meaningful.

Answer 1

This feature has made it into JUnit 4.11.

To use change the name of parameterized tests, you say:

@Parameters(name="namestring")

namestring is a string, which can have the following special placeholders:

• {index} - the index of this set of arguments. The default namestring is {index}.
• {0} - the first parameter value from this invocation of the test.
• {1} - the second parameter value
• and so on

The final name of the test will be the name of the test method, followed by the namestring in brackets, as shown below.

For example (adapted from the unit test for the Parameterized annotation):

@RunWith(Parameterized.class)
static public class FibonacciTest {

    @Parameters( name = "{index}: fib({0})={1}" )
    public static Iterable<Object[]> data() {
        return Arrays.asList(new Object[][] { { 0, 0 }, { 1, 1 }, { 2, 1 },
                { 3, 2 }, { 4, 3 }, { 5, 5 }, { 6, 8 } });
    }

    private final int fInput;
    private final int fExpected;

    public FibonacciTest(int input, int expected) {
        fInput= input;
        fExpected= expected;
    }

    @Test
    public void testFib() {
        assertEquals(fExpected, fib(fInput));
    }

    private int fib(int x) {
        // TODO: actually calculate Fibonacci numbers
        return 0;
    }
}

will give names like testFib[1: fib(1)=1] and testFib[4: fib(4)=3]. (The testFib part of the name is the method name of the @Test).

Answer 2

Looking at JUnit 4.5, its runner clearly doesn't support that, as that logic is buried inside a private class inside the Parameterized class. You could not use the JUnit Parameterized runner, and create your own instead which would understand the concept of names (which leads to the question of how you might set a name ...).

From a JUnit perspective, it would be nice if instead of (or in addition to) just passing an increment, they would pass the comma delimited arguments. TestNG does this. If the feature is important to you, you can comment on the yahoo mailing list referenced at www.junit.org.

Answer 3

I recently came across the same problem when using JUnit 4.3.1. I implemented a new class which extends Parameterized called LabelledParameterized. It has been tested using JUnit 4.3.1, 4.4 and 4.5. It reconstructs the Description instance using the String representation of the first argument of each parameter array from the @Parameters method. You can see the code for this at:

http://code.google.com/p/migen/source/browse/trunk/java/src/.../LabelledParameterized.java?r=3789

and an example of its use at:

http://code.google.com/p/migen/source/browse/trunk/java/src/.../ServerBuilderTest.java?r=3789

The test description formats nicely in Eclipse which is what I wanted since this makes failed tests a lot easier to find! I will probably further refine and document the classes over the next few days/weeks. Drop the '?' part of the URLs if you want the bleeding edge. :-)

To use it, all you have to do is copy that class (GPL v3), and change @RunWith(Parameterized.class) to @RunWith(LabelledParameterized.class) assuming the first element of your parameter list is a sensible label.

I don't know if any later releases of JUnit address this issue but even if they did, I can't update JUnit since all my co-developers would have to update too and we have higher priorities than re-tooling. Hence the work in the class to be compilable by multiple versions of JUnit.

---

Note: there is some reflection jiggery-pokery so that it runs across the different JUnit versions as listed above. The version specifically for JUnit 4.3.1 can be found here and, for JUnit 4.4 and 4.5, here.

Answer 4

With Parameterized as a model, I wrote my own custom test runner / suite -- only took about half an hour. It's slightly different from darrenp's LabelledParameterized in that it lets you specify a name explicitly rather than relying on the first parameter's toString().

It also doesn't use arrays because I hate arrays. :)

public class PolySuite extends Suite {

  // //////////////////////////////
  // Public helper interfaces

  /**
   * Annotation for a method which returns a {@link Configuration}
   * to be injected into the test class constructor
   */
  @Retention(RetentionPolicy.RUNTIME)
  @Target(ElementType.METHOD)
  public static @interface Config {
  }

  public static interface Configuration {
    int size();
    Object getTestValue(int index);
    String getTestName(int index);
  }

  // //////////////////////////////
  // Fields

  private final List<Runner> runners;

  // //////////////////////////////
  // Constructor

  /**
   * Only called reflectively. Do not use programmatically.
   * @param c the test class
   * @throws Throwable if something bad happens
   */
  public PolySuite(Class<?> c) throws Throwable {
    super(c, Collections.<Runner>emptyList());
    TestClass testClass = getTestClass();
    Class<?> jTestClass = testClass.getJavaClass();
    Configuration configuration = getConfiguration(testClass);
    List<Runner> runners = new ArrayList<Runner>();
    for (int i = 0, size = configuration.size(); i < size; i++) {
      SingleRunner runner = new SingleRunner(jTestClass, configuration.getTestValue(i), configuration.getTestName(i));
      runners.add(runner);
    }
    this.runners = runners;
  }

  // //////////////////////////////
  // Overrides

  @Override
  protected List<Runner> getChildren() {
    return runners;
  }

  // //////////////////////////////
  // Private

  private Configuration getConfiguration(TestClass testClass) throws Throwable {
    return (Configuration) getConfigMethod(testClass).invokeExplosively(null);
  }

  private FrameworkMethod getConfigMethod(TestClass testClass) {
    List<FrameworkMethod> methods = testClass.getAnnotatedMethods(Config.class);
    if (methods.isEmpty()) {
      throw new IllegalStateException("@" + Config.class.getSimpleName() + " method not found");
    }
    if (methods.size() > 1) {
      throw new IllegalStateException("Too many @" + Config.class.getSimpleName() + " methods");
    }
    FrameworkMethod method = methods.get(0);
    int modifiers = method.getMethod().getModifiers();
    if (!(Modifier.isStatic(modifiers) && Modifier.isPublic(modifiers))) {
      throw new IllegalStateException("@" + Config.class.getSimpleName() + " method \"" + method.getName() + "\" must be public static");
    }
    return method;
  }

  // //////////////////////////////
  // Helper classes

  private static class SingleRunner extends BlockJUnit4ClassRunner {

    private final Object testVal;
    private final String testName;

    SingleRunner(Class<?> testClass, Object testVal, String testName) throws InitializationError {
      super(testClass);
      this.testVal = testVal;
      this.testName = testName;
    }

    @Override
    protected Object createTest() throws Exception {
      return getTestClass().getOnlyConstructor().newInstance(testVal);
    }

    @Override
    protected String getName() {
      return testName;
    }

    @Override
    protected String testName(FrameworkMethod method) {
      return testName + ": " + method.getName();
    }

    @Override
    protected void validateConstructor(List<Throwable> errors) {
      validateOnlyOneConstructor(errors);
    }

    @Override
    protected Statement classBlock(RunNotifier notifier) {
      return childrenInvoker(notifier);
    }
  }
}

And an example:

@RunWith(PolySuite.class)
public class PolySuiteExample {

  // //////////////////////////////
  // Fixture

  @Config
  public static Configuration getConfig() {
    return new Configuration() {
      @Override
      public int size() {
        return 10;
      }

      @Override
      public Integer getTestValue(int index) {
        return index * 2;
      }

      @Override
      public String getTestName(int index) {
        return "test" + index;
      }
    };
  }

  // //////////////////////////////
  // Fields

  private final int testVal;

  // //////////////////////////////
  // Constructor

  public PolySuiteExample(int testVal) {
    this.testVal = testVal;
  }

  // //////////////////////////////
  // Test

  @Ignore
  @Test
  public void odd() {
    assertFalse(testVal % 2 == 0);
  }

  @Test
  public void even() {
    assertTrue(testVal % 2 == 0);
  }

}

Answer 5

You may also want to try JUnitParams: https://github.com/Pragmatists/JUnitParams

Answer 6

from junit4.8.2, you can create your own MyParameterized class by simply copy Parameterized class. change the getName() and testName() methods in TestClassRunnerForParameters.

Answer 7

None of it was working for me, so I got the source for Parameterized and modified it create a a new test runner. I didn't have to change much but IT WORKS!!!

import java.lang.annotation.ElementType;
import java.lang.annotation.Retention;
import java.lang.annotation.RetentionPolicy;
import java.lang.annotation.Target;
import java.lang.reflect.Constructor;
import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;
import java.lang.reflect.Modifier;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Collection;
import java.util.List;
import org.junit.Assert;
import org.junit.internal.runners.ClassRoadie;
import org.junit.internal.runners.CompositeRunner;
import org.junit.internal.runners.InitializationError;
import org.junit.internal.runners.JUnit4ClassRunner;
import org.junit.internal.runners.MethodValidator;
import org.junit.internal.runners.TestClass;
import org.junit.runner.notification.RunNotifier;

public class LabelledParameterized extends CompositeRunner {
static class TestClassRunnerForParameters extends JUnit4ClassRunner {
    private final Object[] fParameters;

    private final String fParameterFirstValue;

    private final Constructor<?> fConstructor;

    TestClassRunnerForParameters(TestClass testClass, Object[] parameters, int i) throws InitializationError {
        super(testClass.getJavaClass()); // todo
        fParameters = parameters;
        if (parameters != null) {
            fParameterFirstValue = Arrays.asList(parameters).toString();
        } else {
            fParameterFirstValue = String.valueOf(i);
        }
        fConstructor = getOnlyConstructor();
    }

    @Override
    protected Object createTest() throws Exception {
        return fConstructor.newInstance(fParameters);
    }

    @Override
    protected String getName() {
        return String.format("%s", fParameterFirstValue);
    }

    @Override
    protected String testName(final Method method) {
        return String.format("%s%s", method.getName(), fParameterFirstValue);
    }

    private Constructor<?> getOnlyConstructor() {
        Constructor<?>[] constructors = getTestClass().getJavaClass().getConstructors();
        Assert.assertEquals(1, constructors.length);
        return constructors[0];
    }

    @Override
    protected void validate() throws InitializationError {
        // do nothing: validated before.
    }

    @Override
    public void run(RunNotifier notifier) {
        runMethods(notifier);
    }
}

@Retention(RetentionPolicy.RUNTIME)
@Target(ElementType.METHOD)
public static @interface Parameters {
}

private final TestClass fTestClass;

public LabelledParameterized(Class<?> klass) throws Exception {
    super(klass.getName());
    fTestClass = new TestClass(klass);

    MethodValidator methodValidator = new MethodValidator(fTestClass);
    methodValidator.validateStaticMethods();
    methodValidator.validateInstanceMethods();
    methodValidator.assertValid();

    int i = 0;
    for (final Object each : getParametersList()) {
        if (each instanceof Object[])
            add(new TestClassRunnerForParameters(fTestClass, (Object[]) each, i++));
        else
            throw new Exception(String.format("%s.%s() must return a Collection of arrays.", fTestClass.getName(), getParametersMethod().getName()));
    }
}

@Override
public void run(final RunNotifier notifier) {
    new ClassRoadie(notifier, fTestClass, getDescription(), new Runnable() {
        public void run() {
            runChildren(notifier);
        }
    }).runProtected();
}

private Collection<?> getParametersList() throws IllegalAccessException, InvocationTargetException, Exception {
    return (Collection<?>) getParametersMethod().invoke(null);
}

private Method getParametersMethod() throws Exception {
    List<Method> methods = fTestClass.getAnnotatedMethods(Parameters.class);
    for (Method each : methods) {
        int modifiers = each.getModifiers();
        if (Modifier.isStatic(modifiers) && Modifier.isPublic(modifiers))
            return each;
    }

    throw new Exception("No public static parameters method on class " + getName());
}

public static Collection<Object[]> eachOne(Object... params) {
    List<Object[]> results = new ArrayList<Object[]>();
    for (Object param : params)
        results.add(new Object[] { param });
    return results;
}
}

Answer 8

You can create a method like

@Test
public void name() {
    Assert.assertEquals("", inboundFileName);
}

While I wouldn't use it all the time it would be useful to figure out exactly which test number 143 is.

Answer 9

A workaround would be to catch and nest all Throwables into a new Throwable with a custom message that contains all information about the parameters. The message would appear in the stack trace. This works whenever a test fails for all assertions, errors and exceptions as they are all subclasses of Throwable.

My code looks like this:

@RunWith(Parameterized.class)
public class ParameterizedTest {

    int parameter;

    public ParameterizedTest(int parameter) {
        super();
        this.parameter = parameter;
    }

    @Parameters
    public static Collection<Object[]> data() {
        return Arrays.asList(new Object[][] { {1}, {2} });
    }

    @Test
    public void test() throws Throwable {
        try {
            assertTrue(parameter%2==0);
        }
        catch(Throwable thrown) {
            throw new Throwable("parameter="+parameter, thrown);
        }
    }

}

The stack trace of the failed test is:

java.lang.Throwable: parameter=1
    at sample.ParameterizedTest.test(ParameterizedTest.java:34)
Caused by: java.lang.AssertionError
    at org.junit.Assert.fail(Assert.java:92)
    at org.junit.Assert.assertTrue(Assert.java:43)
    at org.junit.Assert.assertTrue(Assert.java:54)
    at sample.ParameterizedTest.test(ParameterizedTest.java:31)
    ... 31 more

Answer 10

I make extensive use of static import for Assert and friends, so it is easy for me to redefine assertion:

private <T> void assertThat(final T actual, final Matcher<T> expected) {
    Assert.assertThat(editThisToDisplaySomethingForYourDatum, actual, expected);
}

For example, you could add a "name" field to your test class, initialized in the constructor, and display that on test failure. Just pass it in as the first elements of your parameters array for each test. This also helps label the data:

public ExampleTest(final String testLabel, final int one, final int two) {
    this.testLabel = testLabel;
    // ...
}

@Parameters
public static Collection<Object[]> data() {
    return asList(new Object[][]{
        {"first test", 3, 4},
        {"second test", 5, 6}
    });
}

Answer 11

When you want the parameter values in test name then you can do something like -

@ParameterizedTest(name="{index} {arguments} then return false" )
@ValueSource(strings = {"false","FALSE","   ","123","abc"})
@DisplayName("When Feature JVM argument is ")
void test_Feature_JVM_Argument_Is_Empty_Or_Blank_Strings_Or_False(String params) {
    System.setProperty("FeatureName", params);
    assertFalse(Boolean.parseBoolean(System.getProperty("FeatureName")));
}

Test name will look like -

JUnit Test image

Answer 12

Since the parameter accessed (e.g. with "{0}" always returns the toString() representation, one workaround would be to make an anonymous implementation and override toString() in each case. For example:

public static Iterable<? extends Object> data() {
    return Arrays.asList(
        new MyObject(myParams...) {public String toString(){return "my custom test name";}},
        new MyObject(myParams...) {public String toString(){return "my other custom test name";}},
        //etc...
    );
}

Answer 13

Parameterized test is calling toString() internally. If you create an object wrapper overiding toString(), it will change the names of the test.

Here is an example, I answered in other post. https://stackoverflow.com/a/67023556/1839360

Answer 14

For a more complex object you may do the following (example with JUnit 4):

@RunWith(Parameterized.class)
public class MainTest {
    private static Object[] makeSample(String[] array, int expectedLength) {
        return new Object[]{array, expectedLength, Arrays.toString(array)};
    }

    @Parameterized.Parameters(name = "for input {2} length should equal {1}")
    public static Collection<Object[]> data() {
        return Arrays.asList(
                makeSample(new String[]{"a"}, 1),
                makeSample(new String[]{"a", "b"}, 2)
        );
    }
    private final int expectedLength;
    private final String[] array;

    public MainTest(String[] array, int expectedLength, String strArray) {
        this.array = array;
        this.expectedLength = expectedLength;
    }

    @Test
    public void should_have_expected_length() {
        assertEquals(expectedLength, array.length);
    }
}

The trick here is to use one input parameter as a string describing either some part of input or the whole test case.

Before adding third parameter it looked like this

And after like this

Answer 15

Check out JUnitParams as dsaff mentioned, works using ant to build parameterized test method descriptions in the html report.

This was after trying LabelledParameterized and finding that it although it works with eclipse it does not work with ant as far as the html report is concerned.

Cheers,