temp-directory-removed.adoc

Note

JUnit Jupiter 5.4 introduced a built-in @TempDir extension. This extension was built before then, but its only advantage over the JUnit Jupiter extension is support for custom file systems. We felt this didn’t have enough value, so we removed this extension in JUnit Pioneer 1.0. We’ve tackled this problem again, and introduced a resource-based extension in version 1.9.0. It allows temporary directories to be created that last longer than a single test method. Give it a try!

The TempDirectory extension can be used to create and clean up a temporary directory for an individual test or all tests in a test class. To use it, simply register the extension and add a parameter of type java.nio.file.Path to your test or lifecycle method or constructor.

For example, the following test registers the extension for a single test method, creates and writes a file to the temporary directory and checks its content.

@Test
@ExtendWith(TempDirectory.class)
void test(@TempDir Path tempDir) {
	Path file = tempDir.resolve("test.txt");
	writeFile(file);
	assertExpectedFileContent(file);
}

In addition to the default file system, the extension can be used with any FileSystem implementation, e.g. Jimfs. In order to use a custom file system, simply register the extension programmatically and pass a provider of a custom parent directory of type Path. The following example uses the Jimfs FileSystem and passes a custom tmp parent directory to the static factory method TempDirectory::createInCustomDirectory.

class MyTests {

	private static FileSystem fileSystem;

	@BeforeAll
	static void createFileSystem() {
		fileSystem = Jimfs.newFileSystem();
	}

	@AfterAll
	static void closeFileSystem() throws Exception {
		fileSystem.close();
	}

	@RegisterExtension
	Extension tempDirectory = TempDirectory.createInCustomDirectory(() ->
		Files.createDirectories(fileSystem.getPath("tmp")));

	@Test
	void test(@TempDir Path tempDir) {
		Path file = tempDir.resolve("test.txt");
		writeFile(file);
		assertExpectedFileContent(file);
	}

}

Thread-Safety

This extension’s thread-safety is undetermined, we recommend to be cautious when using it during parallel test execution. (We’re working on it.)