UT 上手实践

基本工具

Tools

• Junit——Java主流单元测试框架

JUnit 5 = JUnit Platform + JUnit Jupiter + JUnit Vintage

JUnit Platform：测试框架基础，定义了TestEngine用于开发在平台上运行的测试框架的API。
JUnit Jupiter：JUnit5的核心，是一个基于JUnit Platform的引擎实现，它包含许多丰富的新特性来使得自动化测试更加方便和强大。
JUnit Vintage：兼容JUnit3、JUnit4版本的测试引擎，使得旧版本的自动化测试也可以在JUnit5下正常运行。

• Mockito——Java单元测试Mock框架

Annotations

注解	描述
@Test	测试方法
@DisplayName	自定义显示名称
@BeforeAll	在所有单元测试方法执行之前执行一遍
@BeforeEach	在每个单元测试方法执行前都执行一遍
@AfterEach	在每个单元测试方法执行后都执行一遍
@AfterAll	在所有单元测试方法执行之后执行一遍
@Tag	类或方法上声明的标签，用于过滤测试
@Disabled	禁用测试类或测试方法
@Timeout	执行超过给定的时间，则测试失败。
@ParameterizedTest	参数化测试

Assertions

import lombok.AllArgsConstructor;
import lombok.Data;
import org.junit.jupiter.api.Test;

import static java.time.Duration.ofMillis;
import static java.time.Duration.ofMinutes;
import static org.junit.jupiter.api.Assertions.*;

/**
 * AssertionDemoTest
 *
 * @author yuan
 * @since 2021/12/1 09:21
 */
public class AssertionDemoTest {

	private final Calculator calculator = new Calculator();

	private final Person person = new Person("Jane", "Doe");

	@Test
	void standardAssertions() {
		assertEquals(2, calculator.add(1, 1));
		assertEquals(4, calculator.multiply(2, 2),
			"The optional failure message is now the last parameter");
		assertTrue('a' < 'b', () -> "Assertion messages can be lazily evaluated -- "
			+ "to avoid constructing complex messages unnecessarily.");
	}

	@Test
	void groupedAssertions() {
		// In a grouped assertion all assertions are executed, and all
		// failures will be reported together.
		assertAll("person",
			() -> assertEquals("Jane", person.getFirstName()),
			() -> assertEquals("Doe", person.getLastName())
		);
	}

	@Test
	void dependentAssertions() {
		// Within a code block, if an assertion fails the
		// subsequent code in the same block will be skipped.
		assertAll("properties",
			() -> {
				String firstName = person.getFirstName();
				assertNotNull(firstName);

				// Executed only if the previous assertion is valid.
				assertAll("first name",
					() -> assertTrue(firstName.startsWith("J")),
					() -> assertTrue(firstName.endsWith("e"))
				);
			},
			() -> {
				// Grouped assertion, so processed independently
				// of results of first name assertions.
				String lastName = person.getLastName();
				assertNotNull(lastName);

				// Executed only if the previous assertion is valid.
				assertAll("last name",
					() -> assertTrue(lastName.startsWith("D")),
					() -> assertTrue(lastName.endsWith("e"))
				);
			}
		);
	}

	@Test
	void exceptionTesting() {
		Exception exception = assertThrows(ArithmeticException.class, () ->
			calculator.divide(1, 0));
		assertEquals("/ by zero", exception.getMessage());
	}

	@Test
	void timeoutNotExceeded() {
		// The following assertion succeeds.
		assertTimeout(ofMinutes(2), () -> {
			// Perform task that takes less than 2 minutes.
		});
	}

	@Test
	void timeoutNotExceededWithResult() {
		// The following assertion succeeds, and returns the supplied object.
		String actualResult = assertTimeout(ofMinutes(2), () -> {
			return "a result";
		});
		assertEquals("a result", actualResult);
	}

	@Test
	void timeoutNotExceededWithMethod() {
		// The following assertion invokes a method reference and returns an object.
		String actualGreeting = assertTimeout(ofMinutes(2), AssertionDemoTest::greeting);
		assertEquals("Hello, World!", actualGreeting);
	}

	@Test
	void timeoutExceeded() {
		// The following assertion fails with an error message similar to:
		// execution exceeded timeout of 10 ms by 91 ms
		// 超时-任务执行完毕
		assertTimeout(ofMillis(10), () -> {
			// Simulate task that takes more than 10 ms.
			Thread.sleep(100);
		});
	}

	@Test
	void timeoutExceededWithPreemptiveTermination() {
		// The following assertion fails with an error message similar to:
		// execution timed out after 10 ms
		// 超时-则取消任务
		assertTimeoutPreemptively(ofMillis(10), () -> {
			// Simulate task that takes more than 10 ms.
			Thread.sleep(100);
		});
	}

	private static String greeting() {
		return "Hello, World!";
	}


	public static class Calculator {
		public int add(int a, int b) {
			return a + b;
		}

		public int multiply(int a, int b) {
			return a * b;
		}

		public int divide(int a, int b) {
			return a / b;
		}
	}


	@Data
	@AllArgsConstructor
	public static class Person {
		private String firstName;
		private String lastName;
	}
}

小试牛刀

FirstTest

import org.junit.jupiter.api.*;

import static org.junit.jupiter.api.Assertions.assertEquals;

/**
 * FirstTest
 *
 * @author yuan
 * @since 2021/11/29 10:22
 */

public class FirstTest {
  private final Calculator calculator = new Calculator();

  @Test
  @Tag("fast")
  @DisplayName("My 1st JUnit 5 test!