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/* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this
* file, You can obtain one at */
* Provides testing functions dealing with local files and their contents.
import { DownloadPaths } from "resource://gre/modules/DownloadPaths.sys.mjs";
import { FileUtils } from "resource://gre/modules/FileUtils.sys.mjs";
import { Assert } from "resource://testing-common/Assert.sys.mjs";
let gFileCounter = 1;
let gPathsToRemove = [];
export var FileTestUtils = {
* Returns a reference to a temporary file that is guaranteed not to exist and
* to have never been created before. If a file or a directory with this name
* is created by the test, it will be deleted when all tests terminate.
* @param suggestedName [optional]
* Any extension on this template file name will be preserved. If this
* is unspecified, the returned file name will have the generic ".dat"
* extension, which may indicate either a binary or a text data file.
* @return nsIFile pointing to a non-existent file in a temporary directory.
* @note It is not enough to delete the file if it exists, or to delete the
* file after calling nsIFile.createUnique, because on Windows the
* delete operation in the file system may still be pending, preventing
* a new file with the same name to be created.
getTempFile(suggestedName = "test.dat") {
// Prepend a serial number to the extension in the suggested leaf name.
let [base, ext] = DownloadPaths.splitBaseNameAndExtension(suggestedName);
let leafName = base + "-" + gFileCounter + ext;
// Get a file reference under the temporary directory for this test file.
let file = this._globalTemporaryDirectory.clone();
Assert.ok(!file.exists(), "Sanity check the temporary file doesn't exist.");
// Since directory iteration on Windows may not see files that have just
// been created, keep track of the known file names to be removed.
return file;
* Attemps to remove the given file or directory recursively, in a way that
* works even on Windows, where race conditions may occur in the file system
* when creating and removing files at the pace of the test suites.
* The function may fail silently if access is denied. This means that it
* should only be used to clean up temporary files, rather than for cases
* where the removal is part of a test and must be guaranteed.
* @param path
* String representing the path to remove.
async tolerantRemove(path) {
try {
await IOUtils.remove(path, { recursive: true });
} catch (ex) {
// On Windows, we may get an access denied error instead of a no such file
// error if the file existed before, and was recently deleted. There is no
// way to distinguish this from an access list issue because checking for
// the file existence would also result in the same error.
if (
!DOMException.isInstance(ex) || !== "NotFoundError" || !== "NotAllowedError"
) {
throw ex;
* Returns a reference to a global temporary directory that will be deleted
* when all tests terminate.
function () {
// While previous test runs should have deleted their temporary directories,
// on Windows they might still be pending deletion on the physical file
// system. This makes a simple nsIFile.createUnique call unreliable, and we
// have to use a random number to make a collision unlikely.
let randomNumber = Math.floor(Math.random() * 1000000);
let dir = new FileUtils.File(
PathUtils.join(PathUtils.tempDir, `testdir-${randomNumber}`)
dir.createUnique(Ci.nsIFile.DIRECTORY_TYPE, FileUtils.PERMS_DIRECTORY);
// We need to run this *after* the profile-before-change phase because
// otherwise we can race other shutdown blockers who have created files in
// our temporary directory. This can cause our shutdown blocker to fail due
// to, e.g., JSONFile attempting to flush its contents to disk while we are
// trying to delete the file.
IOUtils.sendTelemetry.addBlocker("Removing test files", async () => {
// Remove the files we know about first.
for (let path of gPathsToRemove) {
await FileTestUtils.tolerantRemove(path);
if (!(await IOUtils.exists(dir.path))) {
// Detect any extra files, like the ".part" files of downloads.
for (const child of await IOUtils.getChildren(dir.path)) {
await FileTestUtils.tolerantRemove(child);
// This will fail if any test leaves inaccessible files behind.
await IOUtils.remove(dir.path, { recursive: false });
return dir;