h2 가 test DB 로 선정되는 이유 in DataJpaTest

@Target(ElementType.TYPE) @Retention(RetentionPolicy.RUNTIME) @Documented @Inherited @BootstrapWith(DataJpaTestContextBootstrapper.class) @ExtendWith(SpringExtension.class) @OverrideAutoConfiguration(enabled = false) @TypeExcludeFilters(DataJpaTypeExcludeFilter.class) @Transactional @AutoConfigureCache @AutoConfigureDataJpa @AutoConfigureTestDatabase// -> this annotation! @AutoConfigureTestEntityManager @ImportAutoConfiguration public @interface DataJpaTest { }

@Target({ ElementType.TYPE, ElementType.METHOD }) @Retention(RetentionPolicy.RUNTIME) @Documented @Inherited @ImportAutoConfiguration @PropertyMapping("spring.test.database")// --1 public @interface AutoConfigureTestDatabase { @PropertyMapping(skip = SkipPropertyMapping.ON_DEFAULT_VALUE) Replace replace() default Replace.ANY;// --2 EmbeddedDatabaseConnection connection() default EmbeddedDatabaseConnection.NONE;// --3 enum Replace { ANY, AUTO_CONFIGURED, NONE } }

@Configuration(proxyBeanMethods = false) @AutoConfigureBefore(DataSourceAutoConfiguration.class) public class TestDatabaseAutoConfiguration { @Bean @ConditionalOnProperty(prefix = "spring.test.database", name = "replace", havingValue = "AUTO_CONFIGURED") @ConditionalOnMissingBean public DataSource dataSource(Environment environment) { return new EmbeddedDataSourceFactory(environment).getEmbeddedDatabase(); } @Bean @ConditionalOnProperty(prefix = "spring.test.database", name = "replace", havingValue = "ANY", matchIfMissing = true) public static EmbeddedDataSourceBeanFactoryPostProcessor embeddedDataSourceBeanFactoryPostProcessor() { return new EmbeddedDataSourceBeanFactoryPostProcessor(); } // ... }

@Configuration(proxyBeanMethods = false) @AutoConfigureBefore(DataSourceAutoConfiguration.class) public class TestDatabaseAutoConfiguration { static class EmbeddedDataSourceFactory { EmbeddedDatabase getEmbeddedDatabase() { EmbeddedDatabaseConnection connection = this.environment.getProperty("spring.test.database.connection", EmbeddedDatabaseConnection.class, EmbeddedDatabaseConnection.NONE); if (EmbeddedDatabaseConnection.NONE.equals(connection)) {// -- 1 connection = EmbeddedDatabaseConnection.get(getClass().getClassLoader()); } Assert.state(connection != EmbeddedDatabaseConnection.NONE, "Failed to replace DataSource with an embedded database for tests. If " + "you want an embedded database please put a supported one " + "on the classpath or tune the replace attribute of @AutoConfigureTestDatabase."); return new EmbeddedDatabaseBuilder().generateUniqueName(true).setType(connection.getType()).build(); } }

public static EmbeddedDatabaseConnection get(ClassLoader classLoader) { for (EmbeddedDatabaseConnection candidate : EmbeddedDatabaseConnection.values()) { if (candidate != NONE && ClassUtils.isPresent(candidate.getDriverClassName(), classLoader)) { return candidate; } } return NONE; }

public enum EmbeddedDatabaseConnection { NONE(null, null, null, (url) -> false), H2(EmbeddedDatabaseType.H2, DatabaseDriver.H2.getDriverClassName(), "jdbc:h2:mem:%s;DB_CLOSE_DELAY=-1;DB_CLOSE_ON_EXIT=FALSE", (url) -> url.contains(":h2:mem")), DERBY(EmbeddedDatabaseType.DERBY, DatabaseDriver.DERBY.getDriverClassName(), "jdbc:derby:memory:%s;create=true", (url) -> true), HSQLDB(EmbeddedDatabaseType.HSQL, DatabaseDriver.HSQLDB.getDriverClassName(), "org.hsqldb.jdbcDriver", "jdbc:hsqldb:mem:%s", (url) -> url.contains(":hsqldb:mem:")); //... }