Light and Heavy Tests
Plugin tests run in a real, rather than mocked, IntelliJ Platform environment and use real implementations for most application and project components/services.
Loading and initializing all the project components and services for a project to run tests is a relatively expensive operation, and we want to avoid doing it for each test. Dependently on the loading and execution time, we make a difference between heavy tests and light tests available in IntelliJ Platform test framework:
Heavy tests create a new project for each test.
Light tests reuse a project from the previous test run when possible.
Light and heavy tests use different base classes or fixture classes, as described below.
The standard way of writing a light test is to extend the following classes:
LightPlatformCodeInsightFixtureTestCasefor tests that don't have any Java dependencies.
LightCodeInsightFixtureTestCasefor tests that require the Java PSI or any related functionality.
When writing a light test, you can specify the project's requirements that you need to have in your test, such as the module type, the configured SDK, facets, libraries, etc. You do so by extending the
LightProjectDescriptor class and returning your project descriptor from
getProjectDescriptor(). Before executing each test, the project will be reused if the test case returns the same project descriptor (usually stored in static final field) as the previous one, or recreated if the descriptor is different (
equals() = false ).
The setup code for a multi-module Java project looks something like that: