Module com.github.robtimus.junit.support

Package com.github.robtimus.junit.support.test

Interface CovariantReturnTests<T>

Type Parameters:

T - The type of object to test.

public interface CovariantReturnTests<T>

Base interface for testing that methods return a specific sub type of the overridden method of the super class. This can particularly be useful for testing that chainable method calls remain chainable in the sub class.

Author:

Rob Spoor

Since:

1.1

Method Summary

Modifier and Type	Method	Description
default Class<?>	baseReturnType()	Returns the base return type to test against.
default Class<?>	covariantReturnType()	Returns the covariant return type to test for.
default Stream<Method>	methods()	Returns a stream of methods to test.
Class<T>	objectType()	Returns the type of object to test.
default Stream<DynamicContainer>	testCovariantReturnTypes()	For each method returned by methods(), test that the method is overridden by objectType() and has covariantReturnType() as return type.

Method Detail

objectType

Class<T> objectType()

Returns the type of object to test.

Returns:

The type of object to test.

covariantReturnType

default Class<?> covariantReturnType()

Returns the covariant return type to test for. This default implementation returns objectType().

Returns:

The covariant return type to test for.

baseReturnType

default Class<?> baseReturnType()

Returns the base return type to test against. This default implementation returns the super class of covariantReturnType().

Returns:

The base return type to test against.

methods

default Stream<Method> methods()

Returns a stream of methods to test. This default implementation returns all public methods of the super class of objectType() that have baseReturnType() as return type. Note that this includes static methods; those can be excluded by adding additional filtering:

 @Override
 public Stream<Method> methods() {
     return CovariantReturnTests.super.methods()
             .filter(m -> !Modifier.isStatic(m.getModifiers()));
 }
 

Returns:

A stream of methods to test.

testCovariantReturnTypes

@TestFactory
@DisplayName("covariant return types")
default Stream<DynamicContainer> testCovariantReturnTypes()

For each method returned by methods(), test that the method is overridden by objectType() and has covariantReturnType() as return type.

Returns:

A stream with the tests, one per method.