Introduce support for parameterized tests

[elygre]

Deliverables

• Introduce @TestTemplate and accompanying extension point.
• Determine if Parameter resolvers should be able to access the invocation context for test templates #704 should be included in M4.
• Determine if we need an @InvocationIndex annotation or TestTemplateInfo type for injecting the current invocation index, etc. into @Test, @BeforeEach, and @AfterEach methods.
  • See d2e3a4d
• Introduce junit-jupiter-params module
  • Merge initial contribution (Introduce junit-jupiter-params #728)
  • Javadoc
    • @since tags
  • API annotations
  • Add unit tests where missing (see TODOs)
  • Resolve TODOs
• Document @TestTemplate and accompanying extension point in User Guide and Release Notes
  • Provide example(s) in the documentation module and include in the User Guide. Will be addresses in Document @TestTemplate and accompanying extension point in User Guide #762
• Document parameterized tests in User Guide and Release Notes
  • Document the junit-jupiter-params module in the Dependency Metadata section.
  • Document the junit-jupiter-params module in the Dependency Diagram.
  • Provide example(s) in the documentation module and include in the User Guide.

---

Original Issue Description

At the time of writing, the https://github.com/junit-team/junit-lambda/wiki/Prototype-Test-Decorators page does not have all that much detail, so this might already be considered.

It would be good if the library shipped with ready-to-use simple parameter annotations that could be used inside a single test instance. It would in many ways look like JUnit 4's @Parameterized Runner, but for use inside a single class. When running the test, each @Parameterized method would appear many times, once for each data set.

class MyTest {

   // A simple test with a specified data set
   @Test @Parameterized("mod10")
   void testMod10(String value) { ... }

   @Parameterized("mod10") 
   Collection<Object[]> getMod10Values { ... }

   // Also including a method naming convention
   @Test @Parameterized("mod11", name="{0}")
   void testMod11(String value) { ... }

   @Parameterized("mod11")
   Collection<Object[]> getMod11Values { ... }

   // In the absense of a @Parameterized data provider, use reflection
   @Test @Parameterized("getMod12Values", name="{0}")
   void testMod12(String value) { ... }

   Collection<Object[]> getMod12Values{ ... }
}

---

Related Issues

• Enhance support for dynamic tests #378
• Improve documentation of DynamicTest lifecycle #386
• Allow hierarchical parameterized/dynamic tests #604
• Parameter resolvers should be able to access the invocation context for test templates #704
• Introduce junit-jupiter-params #728

[sbrannen]

@elygre, thanks for raising this issue.

We will certainly provide a mechanism for parameterized tests. We just haven't gotten to it yet in the prototype.

However, we do already have generic support for supplying parameters to methods. This can be achieved by implementing a custom MethodParameterResolver.

Thus, the MethodParameterResolver support is the first building block required for parameterized test support. The next step will be to provide TestExtensions a mechanism for registering tests dynamically.

We will post back here once we begin work on that front.

Regards,

Sam