求助：SystemStubs/Pioneer在Cucumber（JUnit5）步骤定义中失效

问题根源 #

Cucumber拥有独立的测试生命周期，与JUnit 5的扩展机制不兼容。你添加的@ExtendWith(SystemStubsExtension.class)和@SystemStub注解仅对JUnit原生测试方法（比如你的testEnvVar）生效，但无法作用于Cucumber的步骤定义方法，因此environmentVariables实例未被注入，导致空指针异常。

可行解决方案 #

方案1：手动管理SystemStubs实例 #

利用Cucumber的@Before和@After钩子，手动初始化和清理EnvironmentVariables：

import uk.org.webcompere.systemstubs.environment.EnvironmentVariables;
import io.cucumber.java.After;
import io.cucumber.java.Before;
import io.cucumber.java.en.Given;

public class EnvHelperStepDefs {
    private EnvironmentVariables environmentVariables;

    @Before
    public void setUpEnvironment() {
        environmentVariables = new EnvironmentVariables();
    }

    @After
    public void restoreEnvironment() {
        environmentVariables.restore();
    }

    @Given("the environment variable \"HOSTING_MODE\" is set to \"public\"")
    public void hostingModePublic() {
        environmentVariables.set("HOSTING_MODE", "public");
        assert EnvHelper.isPublicMode();
    }
}

方案2：使用SystemStubs的静态工具方法 #

通过静态方法withEnvironmentVariable直接包裹测试逻辑，无需维护实例：

import static uk.org.webcompere.systemstubs.SystemStubs.withEnvironmentVariable;
import io.cucumber.java.en.Given;

public class EnvHelperStepDefs {
    @Given("the environment variable \"HOSTING_MODE\" is set to \"public\"")
    public void hostingModePublic() throws Exception {
        withEnvironmentVariable("HOSTING_MODE", "public")
            .execute(() -> {
                assert EnvHelper.isPublicMode();
            });
    }
}

方案3：自定义Cucumber扩展（进阶） #

如果需要在多个步骤类中复用环境变量管理逻辑，可以自定义Cucumber插件，将SystemStubs的初始化和恢复逻辑整合到Cucumber的生命周期中：

import uk.org.webcompere.systemstubs.environment.EnvironmentVariables;
import io.cucumber.plugin.EventListener;
import io.cucumber.plugin.event.EventPublisher;
import io.cucumber.plugin.event.TestRunFinished;
import io.cucumber.plugin.event.TestRunStarted;

public class SystemStubsCucumberPlugin implements EventListener {
    private EnvironmentVariables environmentVariables;

    @Override
    public void setEventPublisher(EventPublisher publisher) {
        publisher.registerHandlerFor(TestRunStarted.class, event -> {
            environmentVariables = new EnvironmentVariables();
        });

        publisher.registerHandlerFor(TestRunFinished.class, event -> {
            if (environmentVariables != null) {
                environmentVariables.restore();
            }
        });
    }

    public EnvironmentVariables getEnvironmentVariables() {
        return environmentVariables;
    }
}

然后在cucumber.properties中配置插件：

cucumber.plugin=your.package.SystemStubsCucumberPlugin

步骤类中可以通过上下文获取插件实例来使用EnvironmentVariables。

内容的提问来源于stack exchange，提问作者Tirinoarim