CoverageTest.java

package com.example;

import org.junit.Test;
import org.junit.runner.RunWith;
import org.junit.runners.Parameterized;
import org.reflections.Reflections;
import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.RestController;

import java.lang.reflect.Method;
import java.util.Collection;
import java.util.HashSet;
import java.util.stream.Collectors;

import static org.junit.Assert.fail;

@RunWith(Parameterized.class)
public class CoverageTest {

    private Class<?> component;

    public CoverageTest(Class<?> component) {
        this.component = component;
    }

    @Parameterized.Parameters(name = "{0}")
    public static Collection<Object[]> data() {
        final Reflections reflections = new Reflections(CoverageTest.class.getPackage().getName());

        return new HashSet<Class<?>>() {{
            addAll(reflections.getTypesAnnotatedWith(Controller.class));
            addAll(reflections.getTypesAnnotatedWith(RestController.class));
        }}
            .stream()
            .map((klass) -> new Object[]{klass})
            .collect(Collectors.toList());
    }

    @Test
    public void testCoverage() throws Exception {
        String failMessage = "";

        String testClassName = component.getName() + "Test";
        try {
            Class<?> testClass = Class.forName(testClassName);

            for (Method method : component.getDeclaredMethods()) {
                if (!method.getName().endsWith("Action") && !method.getName().startsWith("on")) {
                    continue;
                }

                try {
                    testClass.getDeclaredMethod("test" + method.getName().substring(0, 1).toUpperCase() + method.getName().substring(1));
                } catch (NoSuchMethodException e) {
                    failMessage += "Method " + component + "." + method.getName() + "() not covered.\n";
                }
            }

        } catch (ClassNotFoundException e) {
            failMessage += "Class " + component + " not covered.\n";
        }

        if (failMessage.length() > 0) {
            fail(failMessage);
        }
    }

}