Is there a way to run MySQL in-memory for JUnit test cases?

Question

I'm just trying to add test cases for services accessing a MySQL DB, and I would like to recreate the whole schema (and for some scenarios also just use a MySQL dump file with the data needed for each test case). I was looking around and found some guys using SQLite / H2 and others to do this, but I'm just wandering if there is any way to run MySQL in-memory so I don't need to worry about anything specific to the the MySQL dialect I might be using on our services.

Answer 1

The easiest way for using an in memory database that is fully compatible to MySQL and can be used within JUnit test cases is imho MariaDB4j. you just need a Gradle (/Maven) dependency (http://search.maven.org/#search%7Cga%7C1%7Ca%3A%22mariaDB4j%22) and a few lines of code to start:

DB database = DB.newEmbeddedDB(3306); database.start(); Connection connection = DriverManager.getConnection("jdbc:mysql://localhost/test", "root", ""); 

a startup script can be included via

database.source("path/to/resource.sql"); 

More information on GitHub readme: https://github.com/vorburger/MariaDB4j

EDIT: I have a add some hints to this answer: The MariaDB4j seems to add files in the systems temporary folder. So it will work in an embedded way which means there is no need to install anything and you can just use the dependency via your desired build tool. But it's not a true in-memory-only solution and therefore we cannot speak of unit tests anymore because unit tests mustn't rely on files or databases

Answer 2

We use MySQL and flyway to handle the migration.

For unit testing and simple integration tests, we use the H2 in-memory database with the MODE=MySQL param. Mode=MySQL enables the H2 DB to handle most of the MySQL dialect.

Our test datasource in the Spring config is set up like this:

<bean id="dataSource" class="org.apache.commons.dbcp.BasicDataSource" >     <property name="driverClassName" value="org.h2.Driver"/>     <property name="url" value="jdbc:h2:mem:testdb;MODE=MySQL;DB_CLOSE_DELAY=-1;DB_CLOSE_ON_EXIT=FALSE" /> </bean> 

(If you don't know Spring - the XML translates into calling new BasicDataSource and then call setDriverClassName and setUrl on the instance created)

Then we use Flyway on the datasource to create the schema and read in like we would against a regular MySQL DB:

<bean id="flyway" class="com.googlecode.flyway.core.Flyway" init-method="migrate">     <property name="dataSource" ref="dataSource" />     <property name="cleanOnValidationError" value="false" />     <property name="initOnMigrate" value="true" />     <property name="sqlMigrationSuffix" value=".ddl" /> </bean> 

You could also just use the dataSource bean in a jdbcTemplate and run some SQL scripts that way or run a number of MySQL scripts using the <jdbc:initialize-database...> tag.