Simple hamcrest map matcher which ensures that argument contains given keys and values.

MapMatcher.java

import org.hamcrest.Description;
import org.mockito.ArgumentMatcher;

import java.util.HashMap;
import java.util.Map;
import java.util.Map.Entry;

public class MapMatcher extends ArgumentMatcher<Map> {

    private final Map<Object, Object> map = new HashMap<Object, Object>();

    public MapMatcher(Object ... wantedKeyValuePair) {
        if (wantedKeyValuePair.length > 0 && wantedKeyValuePair.length % 2 != 0) {
            throw new IllegalArgumentException("Invalid number of parameters. Missing value for key " + wantedKeyValuePair[wantedKeyValuePair.length - 1]);
        }

        for (int i = 0; i < wantedKeyValuePair.length; i = i + 2) {
            map.put(wantedKeyValuePair[i], wantedKeyValuePair[i + 1]);
        }
    }

    public MapMatcher(Map wanted) {
        map.putAll(wanted);
    }

    public void describeTo(Description description) {
        description.appendText("map(");

        for (Entry entry : map.entrySet()) {
            description.appendText("{");
            description.appendValue(entry.getKey());
            description.appendText(",");
            description.appendValue(entry.getValue());
            description.appendText("}");
        }

        description.appendText(")");
    }

    @Override
    public boolean matches(Object argument) {
        if (argument instanceof Map) {
            return matches((Map) argument);
        }
        return false;
    }

    private boolean matches(Map argument) {
        for (Object key : map.keySet()) {
            if (!argument.containsKey(key)) {
                return false;
            }

            if (!map.get(key).equals(argument.get(key))) {
                return false;
            }
        }
        return true;
    }

}