SpringBoot, test containers to test queries sent to external DB - spring-boot

Question

My Spring app has its own DB for persistence.
The same app needs to send ad-hoc queries to external databases.
Queries are provided by users.
App takes SQL query provided by user
App takes external database type (postgres / oracle / whatever jdbc)
App submits adhoc query in runtime to external DB
App returns result as json to user
Is there any way to utilize spring test containers in order to test this functionaly?
My goal is:
Write tests for every supported DB
each test starts test container with supported DB (some subset of these I suppose: https://www.testcontainers.org/modules/databases/)
each test uploads sample data to container DB
each test runs set of "must work" queries against it.
I see many examples where App itself is tested against test containers, but can I just start container w/o plugging it as App persistence DB?

Answer 1

can I just start container w/o plugging it as App persistence DB?
Yes, this is perfectly possible.
Testcontainers in itself has nothing to do with Spring or Spring Boot.
What you would do is:
pick the container you want to use (different container for different databases
instantiate the container
start it up
construct a DataSource from it
Use that DataSource for your tests.
Spring Data JDBC does exactly that to run tests against various databases.
I add the class doing that for MySQL in the end.
It is a Spring application context configuration, but you could put that in a JUnit before method, a JUnit 4 rule or a JUnit 5 extension or just a normal method that you call at the start of your test.
#Configuration
#Profile("mysql")
class MySqlDataSourceConfiguration extends DataSourceConfiguration {
private static final MySQLContainer MYSQL_CONTAINER = new MySQLContainer().withConfigurationOverride("");
static {
MYSQL_CONTAINER.start();
}
/*
* (non-Javadoc)
* #see org.springframework.data.jdbc.testing.DataSourceConfiguration#createDataSource()
*/
#Override
protected DataSource createDataSource() {
MysqlDataSource dataSource = new MysqlDataSource();
dataSource.setUrl(MYSQL_CONTAINER.getJdbcUrl());
dataSource.setUser(MYSQL_CONTAINER.getUsername());
dataSource.setPassword(MYSQL_CONTAINER.getPassword());
dataSource.setDatabaseName(MYSQL_CONTAINER.getDatabaseName());
return dataSource;
}
#PostConstruct
public void initDatabase() throws SQLException, ScriptException {
ScriptUtils.executeSqlScript(createDataSource().getConnection(), null, "DROP DATABASE test;CREATE DATABASE test;");
}
}