private void createExtensionDirs() throws IOException {

		ResourceFile extensionDir = appLayout.getExtensionArchiveDir();
		if (!extensionDir.exists()) {
			if (!extensionDir.mkdir()) {
				throw new IOException("Failed to create extension archive directory for test");
			}
		}

		ResourceFile installDir = appLayout.getExtensionInstallationDirs().get(0);
		if (!installDir.exists()) {
			if (!installDir.mkdir()) {
				throw new IOException("Failed to create extension installation directory for test");
			}
		}
	}
Tests for the {@link ExtensionInstaller} class.
Ghidra/Framework/Project/src/test/java/ghidra/framework/project/extensions/ExtensionInstallerTest.java