# Introduction

This sections exaplains the different levels of testing(unit and integration tests) that can(and should) be applied to a Mongock migration and the tools Mongock provides for it.

# Unit testing

Unit tests are a good starting point to ensure the correctness of a migration. With this mechanism the ChangeUnits can be validated in isolation, covering all the changeUnit's methods: Execution, RollbackExecution, BeforeExecution and RollbackBeforeExecution

Mongock doesn't provide any speicific tool for this, but we illustrate how to do it in our example project

A unit test for a change unit looks like this:

ChangeUnit unit test

# Integration test

Once you are confident that the ChangeUnits are tested in isolation, we can increase the testing robustness by adding integration tests. The intent with Integration tests is to test the entire migration suite with your application context and validate the expected database results.

This is a more complex level of testing as it requires to simulate the application context and implies the integration of the different components within the application. But it's probably the most important level of testing to ensure the correctness of the migration.

To see an example, please see our example project

# Integration test with Springboot Runner with Junit5

Mongock provides some useful classes making testing easier. In summary, you need to create your test class extending MongockSpringbootJUnit5IntegrationTestBase, which provides the following

Please follow these steps...

# 1. Import the mongock-springboot-junit5 dependency to your project

Assuming you have imported already mongock-springboot to you project, you only need to add


# 2. Add the additional dependencies to your project

You probably need Springboot starter test, JUnit5, Testcontainers...

# 3. Database initialization.

Although there are multiple ways of doing this, we present what we think provides a good balance easy-flexible

ChangeUnit unit test

# 4. Create the test class extending the MongockSpringbootJUnit5IntegrationTestBase

This class, in addition to extending MongockSpringbootJUnit5IntegrationTestBase, it should also bring the database initialization and the application environment.

This is an example.

Integration test with JUnit5

# Integration test with Springboot Runner WITHOUT Junit5

In this case Mongock provides pretty much the same than in the JUnit5 case, with the exception of the before and after methods, what forces you to make these calls explicitly.

Based on the previous scenario, the relevant modifications are

  1. Import the dependency mongock-springboot-test instead mongock-springboot-junit5
  2. Extend from MongockSpringbootIntegrationTestBase instead MongockSpringbootJUnit5IntegrationTestBase
  3. Explicitly call the methods super.mongockBeforeEach() and super.mongockAfterEach()

The test class should look like this

Integration test without JUnit5

# Integration test with Standalone Runner

The standalone runner provides more control over the process, allowing you to implement integration tests without the need of additional support.

You need to take into account the following

  1. Mongock Runner cannot be execute multiple times, so you need to build a new runner instance and execute it in every test execution.

  2. ConnectionDriver cannot be reused, meaning you need to create a new ConnectionDriver instance in every test execution and provide it to the Mongock builder

  3. If you are sharing the same database for multiple tests, make sure you clean the database, in case you want to start fresh each test case.