Java – Misplaced argument matcher detected here. You cannot use argument matchers outside of verification or stubbing in Mockito

javajunitmockitounit testing

Out of the following two test cases in BundleProcessorTest.java, i am getting below exception, although, my first test case passes successfully.

org.mockito.exceptions.misusing.InvalidUseOfMatchersException:
Misplaced argument matcher detected here:

-> at bundle.test.BundleProcessorTest.bundlePluginShouldNotBeNull(BundleProcessorTest.java:22)

You cannot use argument matchers outside of verification or stubbing.
Examples of correct usage of argument matchers:
when(mock.get(anyInt())).thenReturn(null);
doThrow(new RuntimeException()).when(mock).someVoidMethod(anyObject());
verify(mock).someMethod(contains("foo"))

Also, this error might show up because you use argument matchers with
methods that cannot be mocked. Following methods cannot be
stubbed/verified: final/private/equals()/hashCode().

at
bundle.test.BundleProcessorTest.bundlePluginCollectionShouldNotBeNull(BundleProcessorTest.java:28)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) at
sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source)

Please find below simplified code listing :-

BundlePlugin.java 

package bundle;

import java.util.List;

public class BundlePlugin {

    private final String pluginName ;
    private final List<String> featureContent ;

    public BundlePlugin(String pluginName, List<String> featureContent) {
        super();
        this.pluginName = pluginName;
        this.featureContent = featureContent;
    }

    public String getPluginName() {
        return pluginName;
    }

    public List<String> getFeatureContent() {
        return featureContent;
    }
}

BundleProcessor.java

package bundle;

import java.util.ArrayList;
import java.util.Iterator;
import java.util.List;

public class BundleProcessor {

    public BundlePlugin getBundlePlugin(String pluginName, Iterator<String> artifactIterator) {

        List<String> featureContent = new ArrayList<String>() ;

        return new BundlePlugin(pluginName, featureContent);
    }
}

BundleProcessorTest.java

package bundle.test;

import static org.junit.Assert.assertNotNull;
import static org.mockito.Matchers.anyString;
import static org.mockito.Mockito.mock;

import java.util.Iterator;
import java.util.List;

import org.junit.Test;

import bundle.BundleProcessor;

public class BundleProcessorTest {

    BundleProcessor bundleProcessor = new BundleProcessor() ;   

    @Test
    public void bundlePluginShouldNotBeNull() {

        Iterator<String> artifactIterator = mock(Iterator.class) ;
        bundle.BundlePlugin bundlePlugin = bundleProcessor.getBundlePlugin(anyString(), artifactIterator) ;
        assertNotNull( bundlePlugin );
    }

    @Test
    public void bundlePluginContentShouldNotBeNull() {
        Iterator<String> artifactIterator = mock(Iterator.class) ;
        bundle.BundlePlugin bundlePlugin = bundleProcessor.getBundlePlugin(anyString(), artifactIterator) ;

        List<String> featureContent = bundlePlugin.getFeatureContent() ;
        assertNotNull( featureContent );
    }
}

How to execute this test without problem.

Edit 1:

But if i mark the bundlePluginCollectionShouldNotBeNull test with @Ignore annotation, then first test case passes without any exception.

Best Answer

You are using mockito anyString() while calling the test method, it should be used only for verifying a mock object to ensure a certain method is called with any string parameter inside the test, but not to invoke the test itself. For your test use empty string "" instead to anyString().

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