JUnit 5符合AssertJ

JUnit 5在断言库中带来了很多改进，这主要归功于Java 8和Lambda Expression支持以及新断言（如assertAll ， assertTimeout或assertThrows 。尽管我真的很喜欢JUnit 5，但我相信AssertJ在生产级单元测试中仍然是必须的，我将继续使用它。

但是我认为在单个单元测试中可能会混合使用JUnit 5和AssertJ：其中之一是将JUnit assertAll与AssertJ assertThat混合。

JUnit 5 – assertAll

Assertions.assertAll断言所有提供的可执行文件均不会引发异常：

List<String> owners = Arrays.asList("Betty Davis", "Eduardo Rodriquez");// assert
assertAll(() -> assertTrue(owners.contains("Betty Doe"), "Contains Betty Doe"),() -> assertTrue(owners.contains("John Doe"), "Contains John Doe"),() -> assertTrue(owners.contains("Eduardo Rodriquez"), "Eduardo Rodriquez")
);

上面将报告2个错误：

org.opentest4j.MultipleFailuresError: Multiple Failures (2 failures)Contains Betty Doe ==> expected: <true> but was: <false>Contains John Doe ==> expected: <true> but was: <false>

assertAll执行所有传递的可执行文件，并确保所有传递（不引发异常）。换句话说， assertAll允许分组的断言。

另外， assertAll可用于创建从属断言：

List<String> owners = Arrays.asList("Betty Davis", "Eduardo Rodriquez");// assert
assertAll(() -> {assertTrue(owners.contains("Betty Doe"), "Contains Betty Doe");assertAll(() -> assertNotNull(owners),() -> assertTrue(owners.size() > 1));}
);

在上面的例子中，当第一assertTrue失败后续assertAll将被跳过。

AssertJ –软断言

注意：我在本文中写了更多有关SoftAssertions的内容： AssertJ软断言–我们需要它们吗？

AssertJ提供的SoftAssertions基本上与JUnit 5 assertAll相同，但略有不同，即不支持从属断言。

List<String> owners = Arrays.asList("Betty Davis", "Eduardo Rodriquez");assertSoftly(softAssertions -> {softAssertions.assertThat(owners).contains("Betty Doe");softAssertions.assertThat(owners).contains("John Doe");softAssertions.assertThat(owners).contains("Eduardo Rodriquez");}
);

报告的错误：

1) 
Expecting:<["Betty Davis", "Eduardo Rodriquez"]>
to contain:<["Betty Doe"]>
but could not find:<["Betty Doe"]>at AssertJAssertionsTest.lambda$assertsSoftly$0(AssertJAssertionsTest.java:26)
2) 
Expecting:<["Betty Davis", "Eduardo Rodriquez"]>
to contain:<["John Doe"]>
but could not find:<["John Doe"]>

将JUnit assertAll与AssertJ assertThat混合

混合JUnit的5 assertAll与AssertJ assertThat断言似乎是一个不错的选择：

// arrange
String givenName = "Jean";
String expectedCity = "Monona";
String expectedAddress = "105 N. Lake St.";// act
Optional<Owner> result = testObj.findByName(givenName);// assert
assertThat(result).isPresent();assertAll(() -> assertThat(result.get().getFirstName()).isEqualTo(givenName),() -> assertThat(result.get().getCity()).isEqualTo(expectedCity),() -> assertThat(result.get().getAddress()).isEqualTo(expectedAddress)
);

另一方面， assertAll可以用作assertThat的参数：

// arrange
String givenName = "Jean";
String expectedCity = "Monona";
String expectedAddress = "105 N. Lake St.";// act
Optional<Owner> result = testObj.findByName(givenName);// assert
assertThat(result).hasValueSatisfying(owner -> assertAll(() -> assertThat(owner.getFirstName()).isEqualTo(givenName),() -> assertThat(owner.getCity()).isEqualTo(expectedCity),() -> assertThat(owner.getAddress()).isEqualTo(expectedAddress)
));