@TestPropertySource可以用來覆蓋掉來自於系統環境變量、Java系統屬性、@PropertySource的屬性。
同時@TestPropertySource(properties=...)優先級高於@TestPropertySource(locations=...)。
利用它我們可以很方便的在測試代碼裏微調、模擬配置（比如修改操作系統目錄分隔符、數據源等）。
例子1: 使用Spring Testing工具
我們先使用@PropertySource將一個外部properties文件加載進來，PropertySourceConfig：
@Configuration
@PropertySource("classpath:me/chanjar/annotation/testps/ex1/property-source.properties")
public class PropertySourceConfig {
}
file: property-source.properties
foo=abc
然後我們用@TestPropertySource覆蓋了這個property:
@TestPropertySource(properties = { "foo=xyz" ...
最後我們測試了是否覆蓋成功（結果是成功的）：
@Test
public void testOverridePropertySource() {
assertEquals(environment.getProperty("foo"), "xyz");
}
同時我們還對@TestPropertySource做了一些其他的測試，具體情況你可以自己觀察。爲了方便你觀察@TestPropertySource對系統環境變量和Java系統屬性的覆蓋效果，我們在一開始打印出了它們的值。
源代碼TestPropertyTest：
@ContextConfiguration(classes = PropertySourceConfig.class)
@TestPropertySource(
properties = { "foo=xyz", "bar=uvw", "PATH=aaa", "java.runtime.name=bbb" },
locations = "classpath:me/chanjar/annotation/testps/ex1/test-property-source.properties"
)
public class TestPropertyTest extends AbstractTestNGSpringContextTests implements EnvironmentAware {
private Environment environment;
@Override
public void setEnvironment(Environment environment) {
this.environment = environment;
Map<String, Object> systemEnvironment = ((ConfigurableEnvironment) environment).getSystemEnvironment();
System.out.println("=== System Environment ===");
System.out.println(getMapString(systemEnvironment));
System.out.println();
System.out.println("=== Java System Properties ===");
Map<String, Object> systemProperties = ((ConfigurableEnvironment) environment).getSystemProperties();
System.out.println(getMapString(systemProperties));
}
@Test
public void testOverridePropertySource() {
assertEquals(environment.getProperty("foo"), "xyz");
}
@Test
public void testOverrideSystemEnvironment() {
assertEquals(environment.getProperty("PATH"), "aaa");
}
@Test
public void testOverrideJavaSystemProperties() {
assertEquals(environment.getProperty("java.runtime.name"), "bbb");
}
@Test
public void testInlineTestPropertyOverrideResourceLocationTestProperty() {
assertEquals(environment.getProperty("bar"), "uvw");
}
private String getMapString(Map<String, Object> map) {
return String.join("\n",
map.keySet().stream().map(k -> k + "=" + map.get(k)).collect(toList())
);
}
}
例子2: 使用Spring Boot Testing工具
@TestPropertySource也可以和@SpringBootTest一起使用。
源代碼見TestPropertyTest：
@SpringBootTest(classes = PropertySourceConfig.class)
@TestPropertySource(
properties = { "foo=xyz", "bar=uvw", "PATH=aaa", "java.runtime.name=bbb" },
locations = "classpath:me/chanjar/annotation/testps/ex1/test-property-source.properties"
)
public class TestPropertyTest extends AbstractTestNGSpringContextTests implements EnvironmentAware {
// ...
}