FunctionalStarterApplicationTests.java

@RunWith(SpringRunner.class)
@SpringBootTest(webEnvironment = WebEnvironment.RANDOM_PORT)
public class FunctionalStarterApplicationTests {
  @Autowired
  private TestRestTemplate restTemplate;
  @Test
  public void calculate() {
    assertThat(doCalculate("add", "3", "5")).isEqualTo("8");
    assertThat(doCalculate("subtract", "3", "5")).isEqualTo("-2");
    assertThat(doCalculate("multiply", "3", "5")).isEqualTo("15");
    assertThat(doCalculate("divide", "9", "3")).isEqualTo("3");
  }
  private String doCalculate(final String operator, final String operand1, final String operand2) {
    return this.restTemplate.getForObject(
        String.format("/calculator?operator=%s&v1=%s&v2=%s", operator, operand1, operand2),
        String.class);
  }
}