Migration from JUnit4 to JUnit Jupiter Parameterized Tests

JUnit Jupiters @ParameterizedTest

Since: v2.0

Examples

All examples can be found as integration / acceptance tests in junit-jupiter-params's package com.tngtech.test.junit.dataprovider.

Dependencies

• Replace test dependency org.junit:junit with org.junit.jupiter:junit-jupiter-params and org.junit.jupiter:junit-jupiter-engine

  • Hint: Currently thinking about only using org.junit.jupiter:junit-jupiter-api with lack of ParameterResolver support for dataprovider methods
  • Hint2: see also JUnit5 Migration Tips

• Replace test dependency com.tngtech.java:junit-dataprovider or com.tngtech.junit.dataprovider:junit4-dataprovider with com.tngtech.junit.dataprovider:junit-jupiter-params-dataprovider

Test code

• General: JUnit dataprovider annotations are renamed and moved from com.tngtech.java.junit.dataprovider to com.tngtech.junit.dataprovider

• Remove @RunWith(DataProviderRunner.class) entirely

• Replace @Test with @ParameterizedTest

  • Eclipse search replace if @Test is before dataprovider annotation: @Test(\s*)@(Use)?DataProvider --> @ParameterizedTest$1@$2DataProvider

• Replace usage of FrameworkMethod in a dataprovider method with TestInfo

  • TestInfo#getTestMethod() will provide an Optional<Method> which always contains a test method using it with JUnit dataprovider
  • Note: within a dataprovider method one can new use every parameter resolvable by Parameter Resolution

• One might organize imports for all changed tests files

• Optional: Replace format placeholder %p with %a

  • Note: %p is only deprecated but not removed yet

Framework code

Custom resolver

• Complete resolvers code is completely refactored and resides in core package com.tngtech.junit.dataprovider.resolver now.

• ResolverStrategy was moved to separate class

• Usage of JUnit4s FrameworkMethod was replaced with Javas Method

• Usage of JUnit4s TestClass was replaced with Class<?>

• Note: Method and Class<?> have a lot less features, compared to FrameworkMethod and TestClass but you can use JUnit Jupiters AnnotationSupport and / or ReflectionSupport instead

Custom placeholder

• Customizing the formatter is (currently) not supported via JUnit Jupiter Parameterized Tests (as there is no (easy) way to provide a custom display name formatter to ParameterizedTestExtension)
• Instead you can use @ParameterizedTest#name() to at least minimally customize the display name

Custom converter

Custom DataConverter

• A custom DataConverter can be used by creating a custom (meta) annotation
  • As a starting point you can use CustomConverterDataProviderArgumentProvider from here and use constructor AbstractStringDataProviderArgumentProvider(DataConverter) or AbstractUseDataProviderArgumentProvider(Class, DataConverter) with your custom DataConverter instead

Custom *Converter

• A custom *Converter can be provided
  • via @DataProvider annotation,
  • by creating a custom (meta) annotation, or
  • as default in a custom extension.
• Examples and starting points can be found here.

Custom ObjectArrayConverter

• ObjectArrayConverter is moved to core package com.tngtech.junit.dataprovider.convert

Custom SingleArgConverter

• SingleArgConverter is moved to core package com.tngtech.junit.dataprovider.convert

Custom StringConverter

• StringConverter is moved to core package com.tngtech.junit.dataprovider.convert and refactored
  • @DataProvider parameters are replaced with ConverterContext to be independent from a concrete implementation

Custom TestGenerator and TestValidator

• Removed TestGenerator and put the logic to AbstractDataProviderArgumentProvider and AbstractUseDataProviderArgumentProvider

  • protected TestGenerator#generateExplodedTestMethodsFor(...) --> no pendant available as [JUnit Jupiter Parameterized Test][] behaves completely different
  • TestGenerator#explodeTestMethod(...) --> AbstractUseDataProviderArgumentProvider#invokeDataProviderMethodToRetrieveData(...)
  • TestGenerator#explodeTestMethod(...) --> AbstractDataProviderArgumentProvider#convertData(...)

• Removed TestValidator entirely to adapt to JUnit Jupiter Parameterized Tests behavior which does not validate test cases beforehand

New, missing features and behavioral changes

• TODO is there more?

New features

• JUnit dataprovider methods must no longer be public (same as test methods in JUnit Jupiter)
• JUnit dataprovider methods must no longer be static if and only if class is annotated with @TestInstance(Lifecycle.PER_CLASS)
  • Example: Non-static dataprovider acceptance test
  • JUnit Jupiter documentation on test instance lifcycle
• JUnit dataprovider annotation can be used as meta-annotations to be able to create custom composed annotations
  • Examples: meta acceptance test
  • JUnit Jupter documentation
• Test methods used with JUnit dataprovider can now have additional test method parameters according to ParameterResolver extensions, e.g. TestInfo
  • Note: This does not work for test methods having a varargs parameter
  • JUnit Jupter documentation

Missing features

• Customizing the formatter is (currently) not supported in JUnit Jupiter Parameterized Tests and therefore custom placeholders cannot be used anymore
  • @DataProvider#format() was therefore removed

Behavioral changes

• Default format of a dataprovider test has changed to [{index}] {arguments}, see @ParameterizedTest#name()