Different modes for H2 Database Engine for testing

When testing software that requires a database for persisting data there are different ways to do this. One way is to use a real database engine instance for testing purpose only. Setting up a full scale database server is totally oversized for testing purpose. So using a dedicated simply to use database is a good way. Furthermore the data may not persisted as after the test the data is not necessary anymore. For performance reasons a non-persistent database engine would be great. There are many solutions for in-memory database testing. One of them is H2. Let’s have a look how H2 can be configured for this purpose. Continue reading

Running Junit tests in a specific order

When running tests with Junit, per default the test execution order is deterministic. But the order of all the tests is not predictable. But for some reasons, it may be useful to ensure a specific order. E.g. one of your tests is sometimes failing and you have no idea. So maybe your production code is not threadsafe or there are some other effects that influence your test without knowing it. E.g. a cache that is filled with some results by a test running before. Continue reading

Mocking Resources using JUnit @Rule

When writing unit tests in Java there might be the need to access a resource in the class that should be tested. A common way is to mock the resource. But mocking a simple resource is quite easy. This is supported by mocking frameworks like Mockito, EasyMock or PowerMock. It is a good idea in case you want to test a single action on the mocked resource – e.g. returning a value when accessing a map that contains master data. The following exmaple describes mocking a resource using Mockito. But in case there are complex operations on this resource mocking it is going to be really nasty.
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