JUnit中使用@BeforeAll实例化一个对象returns null

Question

这看起来很简单，我不明白我做错了什么。我正在使用 @BeforeAll 标记创建一个新的 Sequence 对象并在每个测试方法中使用该实例。但是，Sequence 对象似乎为空，我不明白为什么。我确保 @BeforeAll 方法是静态的。

public class SequenceTest {
    static Sequence seq;

    @BeforeAll
    public static void createTestSequence() {

        seq =  new Sequence();
        assertEquals(null, seq);  // this passes when it shouldn't!
    }

    @Test
    public void test1() {
        // do test 
        // fails because Sequence object is null
    }
}

我正在使用 Maven，我在我的 pom.xml 文件中包含了这些依赖项：

<plugin>
    <groupId>org.apache.maven.plugins</groupId>
    <artifactId>maven-surefire-plugin</artifactId>
    <version>2.16</version>
</plugin>

<!-- junit 5, unit test -->
<dependency>
    <groupId>org.junit.jupiter</groupId>
    <artifactId>junit-jupiter-engine</artifactId>
    <version>5.3.1</version>
    <scope>test</scope>
</dependency>

Answer 1

我认为您的块代码应该可以工作。也许你的 maven fire 插件没有运行任何测试？我尝试使用以下块代码但测试失败：

import org.junit.jupiter.api.BeforeAll;
import org.junit.jupiter.api.Test;


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

public class SequenceTest {
    static Sequence seq;

    @BeforeAll
    static void createTestSequence() {

        seq =  new Sequence();
        assertEquals(null, seq);  // this passes when it shouldn't!
    }

    @Test
    public void test1() {
        // do test
        // fails because Sequence object is null
    }
}

class Sequence{

}

我遇到以下错误：

expected: but was: org.tdd.others.Sequence@9b7af25 org.opentest4j.AssertionFailedError: expected: but was: org.tdd.others.Sequence@9b7af25 at org.junit.jupiter.api.AssertionUtils.fail(AssertionUtils.java:55) at org.junit.jupiter.api.AssertionUtils.failNotEqual(AssertionUtils.java:62) at org.junit.jupiter.api.AssertEquals.assertEquals(AssertEquals.java:182) at org.junit.jupiter.api.AssertEquals.assertEquals(AssertEquals.java:177) at org.junit.jupiter.api.Assertions.assertEquals(Assertions.java:1124) at org.tdd.others.SequenceTest.createTestSequence(SequenceTest.java:16) at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)

Answer 2

我使用的是旧的依赖项。更改为：

          <plugin>
                <groupId>org.apache.maven.plugins</groupId>
                <artifactId>maven-surefire-plugin</artifactId>
                <version>3.0.0-M5</version>
            </plugin>

       <!-- junit 5, unit test -->
        <dependency>
            <groupId>org.junit.jupiter</groupId>
            <artifactId>junit-jupiter-engine</artifactId>
            <version>5.4.0</version>
            <scope>test</scope>
        </dependency>

JUnit中使用@BeforeAll实例化一个对象returns null

Using @BeforeAll to instantiate an object in JUnit returns null

java

junit

unit-testing

maven

junit5