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  2. Test Project and Testdata Directories

Test Project and Testdata Directories

Edit pageLast modified: 24 April 2025

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Testing Tutorial and Code Samples

Check out this step-by-step tutorial teaching how to write and run automated tests for your custom language plugin.

Also, code samples comparing_string_references_inspection and conditional_operator_intention demonstrate using tests.

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Configuring Test Frameworks (2024.2+)

All required test-framework dependencies must be declared explicitly.

The test fixture creates a test project environment. Unless you customize the project creation, the test project will have one module with one source root called src. The test project files exist either in a temporary directory or in an in-memory file system, depending on which implementation of TempDirTestFixture is used.

BasePlatformTestCase uses an in-memory implementation; if you set up the test environment by calling IdeaTestFixtureFactory.createCodeInsightFixture(), you can specify the implementation to use.

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If your tests use the in-memory implementation, and you abort the execution of your tests, the persisted filesystem caches may get out of sync with the in-memory structures, and you may get spurious errors in your tests. If you get an unexpected error after a series of successful runs, try rerunning the test, and if that doesn't help, delete the "system" subdirectory in your sandbox directory.

Testdata Files

In your plugin, you usually store the test data for your tests (such as files on which plugin features will be executed and expected output files) in the testdata directory. This is just a directory under your plugin's content root, but not under a source root. Files in testdata usually are not valid source code and must not be compiled.

To specify the location of testdata, you must override the getTestDataPath() method. The default implementation assumes running as part of the IntelliJ Platform source tree and is not appropriate for third-party plugins.

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A widespread pattern in IntelliJ Platform tests is to use the test method's name being executed as the base for building the testdata file paths. This allows us to reuse most of the code between different test methods that test various aspects of the same feature, and this approach is also recommended for third-party plugin tests. The name of the test method can be retrieved using UsefulTestCase.getTestName().

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If your plugin builds on top of Java support, please see How to test a JVM language? to set up your test environment to obtain the required Mock JDK automatically.

To copy files or directories from your testdata directory to the test project directory, you can use the copyFileToProject() and copyDirectoryToProject() methods from CodeInsightTestFixture.

Most operations in plugin tests require a file open in the in-memory editor, in which highlighting, completion, and other operations will be performed. The in-memory editor instance is returned by CodeInsightTestFixture.getEditor(). To copy a file from the testdata directory to the test project directory and immediately open it in the editor, you can use the CodeInsightTestFixture.configureByFile() or configureByFiles() methods. The latter copies multiple files to the test project directory and opens the first of them in the in-memory editor.

Alternatively, you can use one of the other methods, which take parameters annotated with @TestDataFile. These methods copy the specified files from the testdata directory to the test project directory, open the first of the specified files in the in-memory editor, and then perform the requested operation such as highlighting or code completion.

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The IDE supports smart navigation between test code and related test data file(s); see this blog post for more details.

Special Markup

When a file is opened in the in-memory editor, special markup in the file content can specify the caret position or selection.

You can use one of the following markers:

  • <caret> specifies the position where the caret should be placed.

  • <selection> and </selection> specify the start and end of the selected text range.

  • <block> and </block> specify the column selection's start and end points.