Mockito: InvalidUseOfMatchersException

I have a command line tool that performs a DNS check. If the DNS check succeeds, the command proceeds with further tasks. I am trying to write unit tests for this using Mockito. Here's my code:

public class Command() {
    // ....
    void runCommand() {
        // ..
        dnsCheck(hostname, new InetAddressFactory());
        // ..
        // do other stuff after dnsCheck
    }
     
    void dnsCheck(String hostname, InetAddressFactory factory) {
        // calls to verify hostname
    }
}

I am using InetAddressFactory to mock a static implementation of the InetAddress class. Here's the code for the factory:

public class InetAddressFactory {
    public InetAddress getByName(String host) throws UnknownHostException {
        return InetAddress.getByName(host);
    }
}

Here's my unit test case:

@RunWith(MockitoJUnitRunner.class)
public class CmdTest {
    
    // many functional tests for dnsCheck

    // here's the piece of code that is failing
    // in this test I want to test the rest of the code (i.e. after dnsCheck)
    @Test
    void testPostDnsCheck() {
        final Cmd cmd = spy(new Cmd());

        // this line does not work, and it throws the exception below:
        // tried using (InetAddressFactory) anyObject()
        doNothing().when(cmd).dnsCheck(HOST, any(InetAddressFactory.class));
        cmd.runCommand();
    }
}

Exception on running testPostDnsCheck() test:

org.mockito.exceptions.misusing.InvalidUseOfMatchersException: 
Invalid use of argument matchers!
2 matchers expected, 1 recorded.
This exception may occur if matchers are combined with raw values:
    //incorrect:
    someMethod(anyObject(), "raw String");
When using matchers, all arguments have to be provided by matchers.
For example:
    //correct:
    someMethod(anyObject(), eq("String by matcher"));

Any input on how to solve this?

The error message outlines the solution. The line

doNothing().when(cmd).dnsCheck(HOST, any(InetAddressFactory.class))

uses one raw value and one matcher, when it's required to use either all raw values or all matchers. A correct version might read

doNothing().when(cmd).dnsCheck(eq(HOST), any(InetAddressFactory.class))

I had the same problem for a long time now, I often needed to mix Matchers and values and I never managed to do that with Mockito.... until recently ! I put the solution here hoping it will help someone even if this post is quite old.

It is clearly not possible to use Matchers AND values together in Mockito, but what if there was a Matcher accepting to compare a variable ? That would solve the problem... and in fact there is : eq

when(recommendedAccessor.searchRecommendedHolidaysProduct(eq(metas), any(List.class), any(HotelsBoardBasisType.class), any(Config.class)))
            .thenReturn(recommendedResults);

In this example 'metas' is an existing list of values

It might help some one in the future: Mockito doesn't support mocking of 'final' methods (right now). It gave me the same InvalidUseOfMatchersException.

The solution for me was to put the part of the method that didn't have to be 'final' in a separate, accessible and overridable method.

Review the Mockito API for your use case.

For my case, the exception was raised because I tried to mock a package-access method. When I changed the method access level from package to protected the exception went away. E.g. inside below Java class,

public class Foo {
    String getName(String id) {
        return mMap.get(id);
    }
}

the method String getName(String id) has to be AT LEAST protected level so that the mocking mechanism (sub-classing) can work.

Inspite of using all the matchers, I was getting the same issue:

"org.mockito.exceptions.misusing.InvalidUseOfMatchersException: 
Invalid use of argument matchers!
1 matchers expected, 3 recorded:"

It took me little while to figure this out that the method I was trying to mock was a static method of a class(say Xyz.class) which contains only static method and I forgot to write following line:

PowerMockito.mockStatic(Xyz.class);

May be it will help others as it may also be the cause of the issue.

May be helpful for somebody. Mocked method must be of mocked class, created with mock(MyService.class)

Another option is to use a captor: https://www.baeldung.com/mockito-argumentcaptor

// assume deliver takes two values 
@Captor
ArgumentCaptor<String> address; // declare before function call.
Mockito.verify(platform).deliver(address.capture(), any());
String value = address.getValue();
assertEquals(address == "[email protected]");

Captors are especially useful if say one member of the object you want to capture could be a random ID and another is something you can validate against.

Do not use Mockito.anyXXXX(). Directly pass the value to the method parameter of same type. Example:

A expected = new A(10);

String firstId = "10w";
String secondId = "20s";
String product = "Test";
String type = "type2";
Mockito.when(service.getTestData(firstId, secondId, product,type)).thenReturn(expected);

public class A{
   int a ;
   public A(int a) {
      this.a = a;
   }
}