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embedded-database-spring-test

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A library for creating isolated embedded databases for Spring-powered integration tests.

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# <img src="zonky.jpg" height="100"> Embedded Database

## Introduction

The primary goal of this project is to make it easier to write Spring-powered integration tests that rely on `PostgreSQL`, `MSSQL`, `MySQL` or `MariaDB` databases. This library is responsible for creating and managing isolated embedded databases for each test class or test method, based on a test configuration.

## Supported Integrations

* 🌱 **Frameworks:** `Spring` `4.3.8` - `7.0.x`, `Spring Boot` `1.4.6` - `4.0.x`
* 🧪 **Testing frameworks:** `JUnit 5`, `JUnit 4`, `TestNG` and any other supported by Spring
* 🗄️ **Databases:** [PostgreSQL](#postgresql), [MSSQL](#microsoft-sql-server), [MySQL](#mysql), [MariaDB](#mariadb), [H2](#h2), [HSQLDB](#hsqldb), [Derby](#derby)
* 🐳 **Database providers:** [Docker (Testcontainers)](#using-docker-provider-default), [Embedded (Zonky)](#using-zonky-provider-previous-default), ~~[OpenTable](#using-opentable-provider)~~, ~~[Yandex](#using-yandex-provider)~~
* 🔄 **Migration tools:** [Flyway](#flyway), [Liquibase](#liquibase), [Spring `@Sql` annotation](#using-spring-sql-annotation) and others

## Main Goals

Although this library uses `Testcontainers` under the hood (unless you choose a [different provider](#database-providers)), it offers several significant advantages over using `Testcontainers` directly, especially for larger projects with complex schemas and many database migrations. See a more detailed description of the benefits below.

### Easy Integration

You don't have to write any additional code, explore the internals of the Spring framework, deal with context caching and so on.
Just add a maven dependency to your project and declare the `@AutoConfigureEmbeddedDatabase` annotation on a test class and that's all!
You can check out the [quick start](#quick-start) section for more information.

### Migration Caching

The library can cache Flyway and Liquibase migrations in template databases, which means database migrations typically need to be executed only once,
regardless of how many tests use the database. This dramatically reduces initialization time in projects with complex migration scripts.

### Efficient Database Isolation

Using template databases enables fast binary copying of database state. This allows the [refresh mode](#refreshing-the-database-during-tests)
to provide complete test isolation while keeping the refresh operation very fast (typically milliseconds), even for larger databases with committed changes.
The refresh functionality effectively rolls back any changes made during tests.

Additional performance features include [database prefetching](#database-prefetching) and [background bootstrapping mode](#background-bootstrapping-mode).

### Context Caching

You don't need to use the `@DirtiesContext` annotation to get a fresh database anymore!
Use `@AutoConfigureEmbeddedDatabase(refresh = AFTER_CLASS)` or `@AutoConfigureEmbeddedDatabase(refresh = AFTER_EACH_TEST_METHOD)` instead to achieve the ideal isolation of your tests.

The semantics of those annotations is very similar, but the difference in performance is noticeable.
While the `@DirtiesContext` annotation forces a refresh of the entire Spring context, the [refresh mode](#refreshing-the-database-during-tests) of the `@AutoConfigureEmbeddedDatabase` annotation only refreshes data source beans and updates their references in other components.
Depending on the size of the context, the difference can be even several tens of seconds.

## Upgrading from Embedded Database 1.x

If you are upgrading from the `1.x` version, check the [release notes](https://github.com/zonkyio/embedded-database-spring-test/wiki/Embedded-Database-2.0-Release-Notes).
You’ll find [upgrade instructions](https://github.com/zonkyio/embedded-database-spring-test/wiki/Embedded-Database-2.0-Release-Notes#upgrading-from-embedded-database-1x) along with a list of [new and noteworthy](https://github.com/zonkyio/embedded-database-spring-test/wiki/Embedded-Database-2.0-Release-Notes#new-and-noteworthy) features.

## Quick Start

### Maven Configuration

Add the following Maven dependency:

```xml
<dependency>
    <groupId>io.zonky.test</groupId>
    <artifactId>embedded-database-spring-test</artifactId>
    <version>2.8.0</version>
    <scope>test</scope>
</dependency>
```

Also, make sure your application contains a dependency with the database driver for one of the [supported databases](#supported-databases).

### Basic Usage

The configuration of the embedded database is driven by the `@AutoConfigureEmbeddedDatabase` annotation. Just declare the annotation on a test class and that's it! The existing data source will be replaced with the testing one, or a new data source will be created.

## Examples

### Creating a new empty database

A new data source will be created and injected into all related components. You can also inject it into a test class as shown below.

```java
@ExtendWith(SpringExtension.class)
@AutoConfigureEmbeddedDatabase
public class EmptyDatabaseIntegrationTest {
    
    @Autowired
    private DataSource dataSource;
    
    // class body...
}
```

### Replacing an existing data source with an empty database

In case the test class uses a spring context that already contains a data source bean, the data source bean will be automatically replaced with a testing data source.
The newly created data source bean will be injected into all related components, and you can also inject it into a test class.

```java
@ExtendWith(SpringExtension.class)
@AutoConfigureEmbeddedDatabase
@ContextConfiguration("path/to/application-config.xml")
public class EmptyDatabaseIntegrationTest {
    // class body...
}
```

Please note that if the context contains multiple data sources, the bean name must be specified using `@AutoConfigureEmbeddedDatabase(beanName = "dataSource")` to identify the data source that will be replaced.

### Creating multiple databases within a single test class

The `@AutoConfigureEmbeddedDatabase` is a repeatable annotation, so you can annotate a test class with multiple annotations to create multiple independent databases.
Each of them may have completely different configuration parameters, including the database provider as demonstrated in the example below.

```java
@ExtendWith(SpringExtension.class)
@AutoConfigureEmbeddedDatabase(beanName = "dataSource1")
@AutoConfigureEmbeddedDatabase(beanName = "dataSource2", provider = ZONKY)
@AutoConfigureEmbeddedDatabase(beanName = "dataSource3", provider = YANDEX)
public class MultipleDatabasesIntegrationTest {
    
    @Autowired
    private DataSource dataSource1;
    @Autowired
    private DataSource dataSource2;
    @Autowired
    private DataSource dataSource3;
    
    // class body...
}
```

Note that if multiple annotations on a single class are applied, some optimization techniques cannot be used and database initialization or refresh may be slower.

### Refreshing the database during tests

The refresh mode allows you to reset the database to the initial state that existed before the test was started.
You can choose whether the database will be refreshed only between test classes or for each test method,
and whether the refresh should take place before or after the test execution.

Please note that by default, if you do not specify the refresh mode explicitly, all tests in the project share the same database.

```java
@ExtendWith(SpringExtension.class)
@AutoConfigureEmbeddedDatabase(refresh = AFTER_EACH_TEST_METHOD)
public class EmptyDatabaseIntegrationTest {

@Test
        void testMethod1() {
            // fresh database
        }

@Test
        void testMethod2() {
            // fresh database
        }
}
```

This feature uses template databases internally and does not rely on the rollback of the current transaction or cleaning the database.
Therefore, the refresh operation can be relatively fast and efficient, and even the data that has been committed will be reverted.
If database prefetching is used and tuned properly, the refresh operation can only take a few milliseconds even for large databases.

Note that the refresh mode can be combined with `@FlywayTest`, Spring `@Sql` or Spring Boot's annotations without any negative impact on performance.

### Using `@DataJpaTest` or `@JdbcTest` annotation

Spring Boot provides several annotations to simplify writing integration tests.
One of them is the `@DataJpaTest` annotation, which can be used when a test focuses only on JPA components.
By default, the tests annotated with this annotation use an in-memory database.
But if the `@DataJpaTest` annotation is used together with the `@AutoConfigureEmbeddedDatabase` annotation,
the in-memory database is automatically disabled and replaced with an embedded database.

```java
// @ExtendWith(SpringExtension.class) // not needed — @DataJpaTest, @JdbcTest, @JsonTest, @SpringBootTest already include this extension
@DataJpaTest
@AutoConfigureEmbeddedDatabase
public class SpringDataJpaAnnotationTest {
    // class body...
}
```

You can also consider creating a custom [composed annotation](https://github.com/spring-projects/spring-framework/wiki/Spring-Annotation-Programming-Model#composed-annotations).

<details>
  <summary>Example of composed annotation</summary>
  
  ```java
  @Documented
  @Inherited
  @Target(ElementType.TYPE)
  @Retention(RetentionPolicy.RUNTIME)
  @DataJpaTest
  @AutoConfigureEmbeddedDatabase(type = POSTGRES)
  public @interface PostgresDataJpaTest {
  
      @AliasFor(annotation = DataJpaTest.class)
      boolean showSql() default true;
  
      @AliasFor(annotation = DataJpaTest.class)
      boolean useDefaultFilters() default true;
  
      @AliasFor(annotation = DataJpaTest.class)
      Filter[] includeFilters() default {};
  
      @AliasFor(annotation = DataJpaTest.class)
      Filter[] excludeFilters() default {};
  
      @AliasFor(annotation = DataJpaTest.class)
      Class<?>[] excludeAutoConfiguration() default {};
  
  }
  ```

</details>

### Using Spring `@Sql` annotation

Spring provides the `@Sql` annotation that can be used to annotate a test class or test method to configure sql scripts to be run against an embedded database during tests.

```java
@ExtendWith(SpringExtension.class)
@Sql({"/test-schema.sql", "/test-user-data.sql"})
@AutoConfigureEmbeddedDatabase
public class SpringSqlAnnotationTest {
    // class body...
}
```

Note that the `@Sql` annotation can be combined with the [refresh mode](#refreshing-the-database-during-tests).

### Using `@FlywayTest` annotation

The library supports the use of `@FlywayTest` annotation. If you use it, the embedded database will be automatically initialized or cleaned by Flyway. If you don't specify any custom migration locations, the default path `db/migration` will be applied.

Please note that if you declare the annotation on a class, all tests within the class share the same database. If you want all the tests to be isolated, you have to declare the `@FlywayTest` annotation on each test method separately.
Alternatively, you can also use the [refresh mode](#refreshing-the-database-during-tests).

```java
@ExtendWith(SpringExtension.class)
@FlywayTest // performs clean and migrate operations, with the same effect as the refresh mode
@AutoConfigureEmbeddedDatabase
@ContextConfiguration("path/to/application-config.xml")
public class FlywayMigrationIntegrationTest {
    // class body...
}
```

See [Usage of FlywayTest Annotation](https://github.com/flyway/flyway-test-extensions/wiki/Usage-of-Annotation-FlywayTest) for more information about configuration options of the `@FlywayTest` annotation.

## Supported Databases

### PostgreSQL

Before you use PostgreSQL database, you have to add the following Maven dependency:

```xml
<dependency>
    <groupId>org.postgresql</groupId>
    <artifactId>postgresql</artifactId>
    <version>42.7.10</version>
</dependency>
```

Note that the associated database providers support all available features
such as template databases and database prefetching, which provides maximum performance.

### Microsoft SQL Server

Before you use Microsoft SQL Server, you have to add the following Maven dependency:

```xml
<dependency>
    <groupId>com.microsoft.sqlserver</groupId>
    <artifactId>mssql-jdbc</artifactId>
    <version>13.2.1.jre11</version>
</dependency>
```

**In the next step, you will need to accept an EULA for using the docker image.**
See the instructions here: https://www.testcontainers.org/modules/databases/mssqlserver.

Note that the associated database provider supports all available features
such as template databases and database prefetching.
But because Microsoft SQL Server supports only a single template database per database instance,
the template databases are emulated using backup and restore operations.
However, this should have a minimal impact on the resulting performance.

### MySQL

Before you use MySQL database, you have to add the following Maven dependency:

```xml
<dependency>
    <groupId>mysql</groupId>
    <artifactId>mysql-connector-java</artifactId>
    <version>8.0.33</version>
</dependency>
```

**Note that the associated database provider only supports basic features**
**that are required to work the embedded database properly.**
**So you may notice some performance degradation compared to other database providers.**
It's because in MySQL, the `database` keyword is only synonymous with the `schema` keyword,
which makes it hard to implement database prefetching.
Template databases are also not supported and cannot be easily emulated because MySQL does not support fast binary backups.

### MariaDB

Before you use MariaDB database, you have to add the following Maven dependency:

```xml
<dependency>
    <groupId>org.mariadb.jdbc</groupId>
    <artifactId>mariadb-java-client</artifactId>
    <version>3.5.7</version>
</dependency>
```

**Note that the associated database provider only supports basic features**
**that are required to work the embedded database properly.**
**So you may notice some performance degradation compared to other database providers.**
It's because in MariaDB, the `database` keyword is only synonymous with the `schema` keyword,
which makes it hard to implement database prefetching.
Template databases are also not supported and cannot be easily emulated because MariaDB does not support fast binary backups.

### H2

This provider may be convenient if you have an application that supports multiple databases
and you want to reuse the tests using the `@AutoConfigureEmbeddedDatabase` annotation for all these databases, including the H2 database.
In this case, you can override the `zonky.test.database.provider` property externally and change the used database provider for each run without changing the code.
You can find more information about externalized configuration here: https://docs.spring.io/spring-boot/docs/current/reference/html/features.html#features.external-config

Before you use H2 database, you have to add the following Maven dependency:

```xml
<dependency>
    <groupId>com.h2database</groupId>
    <artifactId>h2</artifactId>
    <version>2.4.240</version>
</dependency>
```

**Note that the associated database provider supports database prefetching, but not template databases.
So you may notice some performance degradation compared to other database providers in some cases.**

### HSQLDB

This provider may be convenient if you have an application that supports multiple databases
and you want to reuse the tests using the `@AutoConfigureEmbeddedDatabase` annotation for all these databases, including the HSQLDB database.
In this case, you can override the `zonky.test.database.provider` property externally and change the used database provider for each run without changing the code.
You can find more information about externalized configuration here: https://docs.spring.io/spring-boot/docs/current/reference/html/features.html#features.external-config

Before you use HSQLDB database, you have to add the following Maven dependency:

```xml
<dependency>
    <groupId>org.hsqldb</groupId>
    <artifactId>hsqldb</artifactId>
    <version>2.7.4</version>
</dependency>
```

### Derby

This provider may be convenient if you have an application that supports multiple databases
and you want to reuse the tests using the `@AutoConfigureEmbeddedDatabase` annotation for all these databases, including the Apache Derby database.
In this case, you can override the `zonky.test.database.provider` property externally and change the used database provider for each run without changing the code.
You can find more information about externalized configuration here: https://docs.spring.io/spring-boot/docs/current/reference/html/features.html#features.external-config

Before you use Apache Derby database, you have to add the following Maven dependency:

```xml
<dependency>
    <groupId>org.apache.derby</groupId>
    <artifactId>derby</artifactId>
    <version>10.17.1.0</version>
</dependency>
```

## Supported Migration Tools

Note that although any migration tool is supported,
Flyway and Liquibase provide the best performance
because the embedded database includes extra optimizations for them.

### Flyway

Before you use Flyway, you have to add the following Maven dependency:

```xml
<dependency>
    <groupId>org.flywaydb</groupId>
    <artifactId>flyway-core</artifactId>
    <version>11.20.3</version>
</dependency>
```

Optionally, you may also add the dependency for Flyway test extensions, which allows you to use the `@FlywayTest` annotation.

```xml
<dependency>
    <groupId>org.flywaydb.flyway-test-extensions</groupId>
    <artifactId>flyway-spring-test</artifactId>
    <version>10.0.0</version>
    <scope>test</scope>
</dependency>
```

Note that the processing of the `@FlywayTest` annotation is internally optimized and, if possible,
database prefetching and template databases are used to speed up the application of new migrations after cleaning the database.
This operation is internally identical to the use of the [refresh mode](#refreshing-the-database-during-tests),
which can be used to replace or can be combined with the `@FlywayTest` annotation without any negative impact on performance.

### Liquibase

Before you use Liquibase, you have to add the following Maven dependency:

```xml
<dependency>
    <groupId>org.liquibase</groupId>
    <artifactId>liquibase-core</artifactId>
    <version>5.0.2</version>
</dependency>
```

Given that Liquibase does not offer an analogy to the `@FlywayTest` annotation,
you may consider using the [refresh mode](#refreshing-the-database-during-tests) to refresh an embedded database during tests.

### Spring Boot SQL Init

The library also includes optimized processing of Spring Boot's `spring.sql.init` scripts. If this optimization causes any issues, it can be disabled:

```properties
zonky.test.database.spring.optimized-sql-init.enabled=false
```

## Database Providers

The library can be combined with different database providers.
Each of them has its advantages and disadvantages summarized in the table below.

Docker provides the greatest flexibility, but it can be slightly slower than the native versions.
However, changing the database provider is really easy, so you can try them all.

You can either configure a provider for each class separately via the `@AutoConfigureEmbeddedDatabase(provider = ...)` annotation,
or using the `zonky.test.database.provider` configuration property globally.

[docker-provider]: https://www.testcontainers.org
[zonky-provider]: https://github.com/zonkyio/embedded-postgres
[opentable-provider]: https://github.com/opentable/otj-pg-embedded
[yandex-provider]: https://github.com/yandex-qatools/postgresql-embedded

### Common Configuration

The `@AutoConfigureEmbeddedDatabase` annotation can be used for the basic configuration, the advanced configuration requires properties or yaml files.

```properties
zonky.test.database.type=auto                     # The type of embedded database to be created when replacing the data source.
zonky.test.database.provider=default              # Provider to be used to create the underlying embedded database.
zonky.test.database.refresh=never                 # Determines the refresh mode of the embedded database.
zonky.test.database.replace=any                   # Determines what type of existing DataSource beans can be replaced.

zonky.test.database.init.script-locations=        # Locations of the SQL scripts to apply to the database.
zonky.test.database.init.continue-on-error=false  # Whether initialization should continue when an error occurs.
zonky.test.database.init.separator=;              # Statement separator in the SQL scripts.
zonky.test.database.init.encoding=                # Encoding of the SQL scripts.

zonky.test.database.postgres.client.properties.*= # Additional PostgreSQL options used to configure the test data source.
zonky.test.database.mssql.client.properties.*=    # Additional MSSQL options used to configure the test data source.
zonky.test.database.mysql.client.properties.*=    # Additional MySQL options used to configure the test data source.
zonky.test.database.mariadb.client.properties.*=  # Additional MariaDB options used to configure the test data source.
```

Note that the library includes [configuration metadata](embedded-database-spring-test/src/main/resources/META-INF/spring-configuration-metadata.json) that offer contextual help and code completion as users are working with Spring Boot's `application.properties` or `application.yml` files.

### PostgreSQL Configuration

The following configuration keys are honored by all postgres providers:

```properties
zonky.test.database.postgres.initdb.properties.*= # Additional PostgreSQL options to pass to initdb command during the database initialization.
zonky.test.database.postgres.server.properties.*= # Additional PostgreSQL options used to configure the embedded database server.
```

**Example configuration:**
```properties
zonky.test.database.postgres.client.properties.stringtype=unspecified
zonky.test.database.postgres.initdb.properties.lc-collate=cs_CZ.UTF-8
zonky.test.database.postgres.initdb.properties.lc-monetary=cs_CZ.UTF-8
zonky.test.database.postgres.initdb.properties.lc-numeric=cs_CZ.UTF-8
zonky.test.database.postgres.server.properties.shared_buffers=512MB
zonky.test.database.postgres.server.properties.max_connections=100
```

### Using Docker Provider (default)

This is the default provider, so you do not have to do anything special,
just use the `@AutoConfigureEmbeddedDatabase` annotation in its basic form without specifying any provider.

```java
@ExtendWith(SpringExtension.class)
@AutoConfigureEmbeddedDatabase
public class DefaultProviderIntegrationTest {
    // class body...
}
```

Note that the Docker provider is especially useful if you need to use some database extensions,
or if you want to prepare a custom docker image containing some test data.
In such cases, you can use any docker image compatible with the official docker images of the supported databases.

#### Docker-provider specific configuration

The provider configuration can be managed via properties in the
`zonky.test.database.postgres.docker`, `zonky.test.database.mysql.docker`, `zonky.test.database.mariadb.docker`
and `zonky.test.database.mssql.docker` groups as shown below.

```properties
zonky.test.database.postgres.docker.image=postgres:11-alpine        # Docker image containing PostgreSQL database.
zonky.test.database.postgres.docker.tmpfs.enabled=false             # Whether to mount postgres data directory as tmpfs.
zonky.test.database.postgres.docker.tmpfs.options=rw,noexec,nosuid  # Mount options used to configure the tmpfs filesystem.

zonky.test.database.mysql.docker.image=mysql:5.7                    # Docker image containing MySQL database.
zonky.test.database.mysql.docker.tmpfs.enabled=false                # Whether to mount database data directory as tmpfs.
zonky.test.database.mysql.docker.tmpfs.options=rw,noexec,nosuid     # Mount options used to configure the tmpfs filesystem.

zonky.test.database.mariadb.docker.image=mariadb:10.4               # Docker image containing MariaDB database.
zonky.test.database.mariadb.docker.tmpfs.enabled=false              # Whether to mount database data directory as tmpfs.
zonky.test.database.mariadb.docker.tmpfs.options=rw,noexec,nosuid   # Mount options used to configure the tmpfs filesystem.

zonky.test.database.mssql.docker.image=mcr.microsoft.com/mssql/server:2017-latest # Docker image containing MSSQL database.
```

Or, the provider configuration can also be customized with a bean implementing `PostgreSQLContainerCustomizer` interface.

```java
import io.zonky.test.db.config.PostgreSQLContainerCustomizer;

@Configuration
public class EmbeddedPostgresConfiguration {
    
    @Bean
    public PostgreSQLContainerCustomizer postgresContainerCustomizer() {
        return container -> container.withStartupTimeout(Duration.ofSeconds(60L));
    }
}
```

```java
@ExtendWith(SpringExtension.class)
@AutoConfigureEmbeddedDatabase
@ContextConfiguration(classes = EmbeddedPostgresConfiguration.class)
public class EmbeddedPostgresIntegrationTest {
    // class body...
}
```

### Using Zonky Provider (previous default)

Before you use the Zonky provider, you have to add the following Maven dependency:

```xml
<dependency>
    <groupId>io.zonky.test</groupId>
    <artifactId>embedded-postgres</artifactId>
    <version>2.2.2</version>
    <scope>test</scope>
</dependency>
```

Then, you can use the `@AutoConfigureEmbeddedDatabase` annotation to set up the `DatabaseProvider.ZONKY` provider.

```java
@ExtendWith(SpringExtension.class)
@AutoConfigureEmbeddedDatabase(provider = ZONKY)
public class ZonkyProviderIntegrationTest {
    // class body...
}
```

Note that the Zonky provider can be useful as an alternative if you can't use Docker for some reason,
and in version `1.x.x` it used to be the default provider.

#### Changing the version of postgres binaries

The version of the binaries is configurable at compile time by importing `embedded-postgres-binaries-bom` in a required version into your dependency management section.

```xml
<dependencyManagement>
    <dependencies>
        <dependency>
            <groupId>io.zonky.test.postgres</groupId>
            <artifactId>embedded-postgres-binaries-bom</artifactId>
            <version>18.3.0</version>
            <type>pom</type>
            <scope>import</scope>
        </dependency>
    </dependencies>
</dependencyManagement>
```

Find more information about this topic here: https://github.com/zonkyio/embedded-postgres#postgres-version

#### Enabling support for additional architectures

By default, only the support for `amd64` architecture is enabled.
Support for other architectures can be enabled using the following instructions:
https://github.com/zonkyio/embedded-postgres#additional-architectures

#### Zonky-provider specific configuration

The provider configuration can be customized with a bean implementing `Consumer<EmbeddedPostgres.Builder>` interface.
The obtained builder provides methods to change the configuration before the database is started.

```java
import io.zonky.test.db.postgres.embedded.EmbeddedPostgres;

@Configuration
public class EmbeddedPostgresConfiguration {
    
    @Bean
    public Consumer<EmbeddedPostgres.Builder> embeddedPostgresCustomizer() {
        return builder -> builder.setPGStartupWait(Duration.ofSeconds(60L));
    }
}
```

```java
@ExtendWith(SpringExtension.class)
@AutoConfigureEmbeddedDatabase(provider = ZONKY)
@ContextConfiguration(classes = EmbeddedPostgresConfiguration.class)
public class EmbeddedPostgresIntegrationTest {
    // class body...
}
```

### Using OpenTable Provider

> **Deprecated:** OpenTable provider has been deprecated in favor of Embedded (Zonky) provider and is scheduled to be removed in the next major version.

Before you use the OpenTable provider, you have to add the following Maven dependency:

```xml
<dependency>
    <groupId>com.opentable.components</groupId>
    <artifactId>otj-pg-embedded</artifactId>
    <version>0.13.1</version>
    <scope>test</scope>
</dependency>
```

Then, you can use the `@AutoConfigureEmbeddedDatabase` annotation to set up the `DatabaseProvider.OPENTABLE` provider.

```java
@ExtendWith(SpringExtension.class)
@AutoConfigureEmbeddedDatabase(provider = OPENTABLE)
public class OpenTableProviderIntegrationTest {
    // class body...
}
```

#### OpenTable-provider specific configuration

```java
import com.opentable.db.postgres.embedded.EmbeddedPostgres;

```java
@ExtendWith(SpringExtension.class)
@AutoConfigureEmbeddedDatabase(provider = OPENTABLE)
@ContextConfiguration(classes = EmbeddedPostgresConfiguration.class)
public class EmbeddedPostgresIntegrationTest {
    // class body...
}
```

### Using Yandex Provider

> **Deprecated:** Yandex provider has been deprecated in favor of Embedded (Zonky) provider and is scheduled to be removed in the next major version.

Before you use the Yandex provider, you have to add the following Maven dependency:

```xml
<dependency>
    <groupId>ru.yandex.qatools.embed</groupId>
    <artifactId>postgresql-embedded</artifactId>
    <version>2.10</version>
    <scope>test</scope>
</dependency>
```

Then, you can use the `@AutoConfigureEmbeddedDatabase` annotation to set up the `DatabaseProvider.YANDEX` provider.

```java
@ExtendWith(SpringExtension.class)
@AutoConfigureEmbeddedDatabase(provider = YANDEX)
public class YandexProviderIntegrationTest {
    // class body...
}
```

#### Yandex-provider specific configuration

The provider configuration can be managed via properties in the `zonky.test.database.postgres.yandex-provider` group.

```properties
zonky.test.database.postgres.yandex-provider.postgres-version=11.10-1 # Version of EnterpriseDB PostgreSQL binaries (https://www.enterprisedb.com/download-postgresql-binaries).
```

## Advanced Topics

### Database Prefetching

The database prefetching feature is used to speed up the initialization of new databases by loading the databases in advance and maintaining them in an internal buffer to make them available as fast as possible. The prefetching can be customized by properties in the `zonky.test.database.prefetching` group.

```properties
zonky.test.database.prefetching.thread-name-prefix=prefetching- # Prefix to use for the names of database prefetching threads.
zonky.test.database.prefetching.concurrency=3                   # Maximum number of concurrently running database prefetching threads.
zonky.test.database.prefetching.pipeline-cache-size=5           # Maximum number of prepared databases per pipeline.
zonky.test.database.prefetching.max-prepared-templates=10       # Maximum number of prepared database templates.
```

### Disabling auto-configuration

By default, the library automatically registers all necessary context customizers and test execution listeners.
If this behavior is inappropriate for some reason, you can deactivate it by excluding the `embedded-database-spring-test-autoconfigure` dependency.

```xml
<dependency>
    <groupId>io.zonky.test</groupId>
    <artifactId>embedded-database-spring-test</artifactId>
    <version>2.8.0</version>
    <scope>test</scope>
    <exclusions>
        <exclusion>
            <groupId>io.zonky.test</groupId>
            <artifactId>embedded-database-spring-test-autoconfigure</artifactId>
        </exclusion>
    </exclusions>
</dependency>
```

### Background bootstrapping mode

This feature is enabled out of the box and causes that the initialization of the data source and the execution of Flyway or Liquibase migrations are performed in background bootstrap mode.
In such case, a `DataSource` proxy is immediately returned for injection purposes instead of waiting for the bootstrapping to complete.
However, note that the first actual call to a data source method will then block until the bootstrapping is completed, if not ready by then.
For maximum benefit, make sure to avoid early data source calls in init methods of related beans.

## Troubleshooting

### Connecting to the embedded database

When you use a breakpoint to pause the test, you can connect to the temporary embedded database. Connection details can be found in the log as shown in the example below:

```log
i.z.t.d.l.EmbeddedDatabaseReporter - JDBC URL to connect to 'dataSource1': url='jdbc:postgresql://localhost:55112/fynwkrpzfcyj?user=postgres', scope='TestClass#testMethod'
```

**TIP:** You can use the following **IntelliJ IDEA plugin to automatically synchronize the database settings** according to the connection strings in the log produced by the library:
https://gist.github.com/tomix26/9e1ea63353707ef3b5cf4869fc50eec2

Note that if you are using the [refresh mode](#refreshing-the-database-during-tests) or the `@FlywayTest` annotation, there may be several similar records in the log but always with a different scope. That's because in this case multiple isolated databases may be created.

### Process [/tmp/embedded-pg/PG-XYZ/bin/initdb, ...] failed

Check the console output for the `initdb: cannot be run as root` message. If the error is present, try to upgrade to a newer version of the library (1.5.5+), or ensure the build process is running as a non-root user.

If the error is not present, try to clean up the `/tmp/embedded-pg/PG-XYZ` directory containing temporary binaries of the embedded database.

### Running tests on Windows does not work

You probably need to install [Microsoft Visual C++ 2013 Redistributable Package](https://support.microsoft.com/en-us/help/3179560/update-for-visual-c-2013-and-visual-c-redistributable-package). The 2013 version is important, installing other versions does not help. The problem is discussed in more detail [here](https://github.com/opentable/otj-pg-embedded/issues/65).

### Running tests in Docker does not work

Running builds inside a Docker container is fully supported, including Alpine Linux. However, PostgreSQL is restricted in that the database process must run under a non-root user. Otherwise, the database does not start and fails with an error.

So be sure to use a docker image that runs with a non-root user. Or, since version `1.5.5` you can run the docker container with the `--privileged` option, which allows to take advantage of the `unshare` command to run the database process in a separate namespace.

Below are some examples of how to prepare a docker image running with a non-root user:

<details>
  <summary>Standard Dockerfile</summary>
  
  ```dockerfile
  FROM openjdk:8-jdk
  
  RUN groupadd --system --gid 1000 test
  RUN useradd --system --gid test --uid 1000 --shell /bin/bash --create-home test
  
  USER test
  WORKDIR /home/test
  ```

</details>

<details>
  <summary>Alpine Dockerfile</summary>
  
  ```dockerfile
  FROM openjdk:8-jdk-alpine
  
  RUN addgroup -S -g 1000 test
  RUN adduser -D -S -G test -u 1000 -s /bin/ash test
  
  USER test
  WORKDIR /home/test
  ```

</details>

<details>
  <summary>Gitlab runner Docker executor</summary>

Configure the Docker container to run in privileged mode as described [here](https://docs.gitlab.com/runner/executors/docker.html#use-docker-in-docker-with-privileged-mode).

```
  [[runners]]
    executor = "docker"
    [runners.docker]
      privileged = true
  ```

</details>

### Using Docker provider inside a Docker container

This combination is supported, however, additional configuration is required.
You have to add the `-v /var/run/docker.sock:/var/run/docker.sock` mapping to the Docker command to map the Docker socket.
Detailed instructions can be found [here](https://www.testcontainers.org/supported_docker_environment/continuous_integration/dind_patterns/).

### Frequent and repeated initialization of the database

Make sure you do not use `org.flywaydb.test.junit.FlywayTestExecutionListener` or `org.flywaydb.test.FlywayTestExecutionListener` listeners. Because this library has its own test execution listener that can optimize database initialization.
But this optimization has no effect if any of these listeners is also applied.

## Building from Source
The project uses a [Gradle](http://gradle.org)-based build system. In the instructions
below, [`./gradlew`](http://vimeo.com/34436402) is invoked from the root of the source tree and serves as
a cross-platform, self-contained bootstrap mechanism for the build.

### Prerequisites

[Git](http://help.github.com/set-up-git-redirect) and [JDK 8 or later](http://www.oracle.com/technetwork/java/javase/downloads)

Be sure that your `JAVA_HOME` environment variable points to the `jdk1.8.0` folder
extracted from the JDK download.

### Check out sources
`git clone git@github.com:zonkyio/embedded-database-spring-test.git`

### Compile and test
`./gradlew build`

## Project dependencies

* [Spring Framework](https://spring.io/) (5.3.39) - `spring-test`, `spring-context` modules
* [Testcontainers](https://www.testcontainers.org) (1.21.4)
* [Cedarsoftware](https://github.com/jdereg/java-util) (1.68.0)
* [Guava](https://github.com/google/guava) (33.4.8-jre)

## License
The project is released under version 2.0 of the [Apache License](http://www.apache.org/licenses/LICENSE-2.0.html).

embedded-database-spring-test

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