in my test I have the following line:
when(client.runTask(anyString(), anyString(), isA(Iterable.class)).thenReturn(...)
isA(Iterable.class)
produces warning that it needs unchecked conversion to conform to Iterable<Integer>
. What is syntax for that?
isA(Iterable<Integer>.class)
isA((Iterable<Integer>)Iterable.class
do not work.
Any suggestions?
Yes, this is a general problem with Mockito/Hamcrest. Generally using isA()
with generic classes produces a warning.
There are predifined Mockito matchers for the most common generic classes: anyList(), anyMap()
, anySet()
and anyCollection()
.
Suggestions:
Mockito 2.1.0 added a new anyIterable() method for matching Iterables:
when(client.runTask(anyString(), anyString(), anyIterable()).thenReturn(...)
If you just want to get rid of the warning in Eclipse. Option exists since Eclipse Indigo:
Window > Preferences > Java > Compiler > Errors/Warnings > Generic types > Ignore unavoidable generic type problems
I suggest you do this if you have the problem only once. I personally don't remember ever needing an isA(Iterable.class)
.
As Daniel Pryden says, you can limit the @SuppressWarnings
to a local variable or a helper method.
This solves the problem for good. But it has two disadvantages:
TypeToken
class. Here I used the TypeToken class from Guava. There's also a TypeToken
class in Gson and a GenericType
in JAX-RS.Using the generic matcher:
import static com.arendvr.matchers.InstanceOfGeneric.isA;
import static org.mockito.ArgumentMatchers.argThat;
// ...
when(client.runTask(anyString(), anyString(), argThat(isA(new TypeToken<Iterable<Integer>>() {}))))
.thenReturn(...);
Generic matcher class:
package com.arendvr.matchers;
import com.google.common.reflect.TypeToken;
import org.mockito.ArgumentMatcher;
public class InstanceOfGeneric<T> implements ArgumentMatcher<T> {
private final TypeToken<T> typeToken;
private InstanceOfGeneric(TypeToken<T> typeToken) {
this.typeToken = typeToken;
}
public static <T> InstanceOfGeneric<T> isA(TypeToken<T> typeToken) {
return new InstanceOfGeneric<>(typeToken);
}
@Override
public boolean matches(Object item) {
return item != null && typeToken.getRawType().isAssignableFrom(item.getClass());
}
}