Spring Boot Mocking Groovy REST Controller

HelloControllerTests.groovy

/**
 * 
 * How to Unit test Spring Boot REST Controller with mocks
 * 
 * Requires Groovy mockito support dependency in build.gradle:
 *
 *     testCompile("org.springframework.boot:spring-boot-starter-test")
 * 
 * Otherwise mocks crash with NPE..
 * See https://github.com/cyrusinnovation/mockito-groovy-support
 * 
 */package demo

import org.junit.Assert;
import org.junit.Before;
import org.junit.Test;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.http.MediaType
import org.springframework.test.context.web.WebAppConfiguration
import org.springframework.test.web.servlet.MockMvc;
import org.springframework.test.web.servlet.MvcResult;
import org.springframework.test.web.servlet.request.MockMvcRequestBuilders
import org.springframework.test.web.servlet.setup.MockMvcBuilders;

import org.mockito.InjectMocks;
import org.mockito.Mock;
import org.mockito.MockitoAnnotations
import org.springframework.web.context.WebApplicationContext;
import static org.mockito.Matchers.any;
import static org.mockito.Mockito.times;
import static org.mockito.Mockito.verify;
import static org.mockito.Mockito.when;

@WebAppConfiguration
class HelloControllerTests {

    @Mock
    private HelloService helloService

    @InjectMocks
    private HelloController helloController

    protected MockMvc mvc;

    @Autowired
    protected WebApplicationContext webApplicationContext;


    @Before
    void beforeEachTest() {

        MockitoAnnotations.initMocks(this)

        mvc = MockMvcBuilders.standaloneSetup(helloController).build()

    }

    @Test
    void testHello() {

        Hello data = new Hello([name:"Test says hello"])

        when(helloService.doHello()).thenReturn(data)

        String uri = "/hello";

        MvcResult result = mvc.perform( MockMvcRequestBuilders.get(uri).accept(MediaType.APPLICATION_JSON)).andReturn();

        String content = result.getResponse().getContentAsString();
        int status = result.getResponse().getStatus();

        verify(helloService, times(1)).doHello();

        assert status == 200
        assert content.trim().size() > 0
        assert content.trim() == '{"name":"Test says hello"}'
        println content

    }
}