如何测试@ConditionalOnClass与@ConditionalOnBean注解的JUnit用例？

问题场景 #

配置类代码：

@Configuration
@ConditionalOnClass({SomeKeyService.class})
@EnableConfigurationProperties({SomeConfig.class})
public class MyServiceAutoConfig {

    @Bean
    @ConditionalOnProperty("certificate.password")
    @ConditionalOnBean(KeyStore.class)
    @ConditionalOnMissingBean
    public someClass myService(KeyStore ks, SomeConfig config) {
        return new someClass(ks, config.getPassword());
    }
}

测试类代码：

public class MyServiceAutoConfigTest{
    ApplicationRunner context = new ApplicationRunner().withConfiguration(AutoConfigurations.of(MyServiceAutoConfig.class));

    @Test
    public void givenPropertyShouldHaveSomeClassBean() {
        this.context.withUserConfiguration(MyServiceAutoConfig.class, SomeConfig.class)
            .withPropertyValues("certificate.password=hdgjashjfdjcn")
            .run((context) -> {assertThat(context).hasSingleBean(someClass.class);});
    }
}

补充说明：someClass实现了SomeKeyService，KeyStore为java.security.KeyStore。测试时出现错误：no beans found of that type。

解决方案 #

测试失败的核心原因是测试上下文缺少KeyStore类型的Bean，同时存在测试配置冗余问题，修正步骤如下：

1. 为测试上下文提供KeyStore Bean #

配置类中的myService Bean依赖KeyStore实例，但当前测试上下文未注入该Bean，导致@ConditionalOnBean(KeyStore.class)条件不满足，Bean无法创建。可通过ApplicationRunner的withBean方法直接注入模拟实例：

this.context
    .withBean(KeyStore.class, () -> {
        try {
            KeyStore ks = KeyStore.getInstance(KeyStore.getDefaultType());
            ks.load(null, null);
            return ks;
        } catch (Exception e) {
            throw new RuntimeException(e);
        }
    })

2. 移除冗余的测试配置 #

AutoConfigurations.of(MyServiceAutoConfig.class)已经将自动配置类纳入测试上下文，无需再通过withUserConfiguration重复添加MyServiceAutoConfig.class。

3. 确保SomeConfig的属性绑定生效 #

确认SomeConfig类上添加了@ConfigurationProperties注解，否则无法正确绑定certificate.password属性：

@ConfigurationProperties(prefix = "certificate")
public class SomeConfig {
    private String password;

    // getter、setter方法
}

修改后的完整测试类 #

public class MyServiceAutoConfigTest{
    ApplicationRunner context = new ApplicationRunner()
        .withConfiguration(AutoConfigurations.of(MyServiceAutoConfig.class));

    @Test
    public void givenPropertyShouldHaveSomeClassBean() {
        this.context
            .withUserConfiguration(SomeConfig.class)
            .withPropertyValues("certificate.password=hdgjashjfdjcn")
            .withBean(KeyStore.class, () -> {
                try {
                    KeyStore ks = KeyStore.getInstance(KeyStore.getDefaultType());
                    ks.load(null, null);
                    return ks;
                } catch (Exception e) {
                    throw new RuntimeException(e);
                }
            })
            .run((context) -> {
                assertThat(context).hasSingleBean(someClass.class);
            });
    }
}

额外测试建议 #

可以补充多场景测试覆盖所有Conditional条件：

• 测试当certificate.password属性不存在时，someClass Bean不创建
• 测试当已有someClass Bean时，自动配置的Bean不重复创建
• 测试当KeyStore Bean不存在时，someClass Bean不创建

内容的提问来源于stack exchange，提问作者unknown