new file mode 100644
--- /dev/null
+++ b/browser/components/sessionstore/test/unit/test_migration_lz4compression.js
@@ -0,0 +1,132 @@
+"use strict";
+
+const {XPCOMUtils} = Cu.import("resource://gre/modules/XPCOMUtils.jsm", {});
+const {SessionWorker} = Cu.import("resource:///modules/sessionstore/SessionWorker.jsm", {});
+
+var Paths;
+var SessionFile;
+
+// We need a XULAppInfo to initialize SessionFile
+Cu.import("resource://testing-common/AppInfo.jsm", this);
+updateAppInfo({
+ name: "SessionRestoreTest",
+ ID: "{230de50e-4cd1-11dc-8314-0800200c9a66}",
+ version: "1",
+ platformVersion: "",
+});
+
+function run_test() {
+ run_next_test();
+}
+
+function promise_check_exist(path, shouldExist) {
+ return (async function() {
+ do_print("Ensuring that " + path + (shouldExist ? " exists" : " does not exist"));
+ if ((await OS.File.exists(path)) != shouldExist) {
+ throw new Error("File " + path + " should " + (shouldExist ? "exist" : "not exist"));
+ }
+ })();
+}
+
+function promise_check_contents(path, expect) {
+ return (async function() {
+ do_print("Checking whether " + path + " has the right contents");
+ let actual = await OS.File.read(path, { encoding: "utf-8", compression: "lz4" });
+ Assert.deepEqual(JSON.parse(actual), expect, `File ${path} contains the expected data.`);
+ })();
+}
+
+function generateFileContents(id) {
+ let url = `http://example.com/test_backup_once#${id}_${Math.random()}`;
+ return {windows: [{tabs: [{entries: [{url}], index: 1}]}]}
+}
+
+// Check whether the migration from .js to .jslz4 is correct.
+add_task(async function test_migration() {
+ // Make sure that we have a profile before initializing SessionFile.
+ let profd = do_get_profile();
+ SessionFile = Cu.import("resource:///modules/sessionstore/SessionFile.jsm", {}).SessionFile;
+ Paths = SessionFile.Paths;
+
+ let source = do_get_file("data/sessionstore_valid.js");
+ source.copyTo(profd, "sessionstore.js");
+
+ // Read the content of the session store file.
+ let sessionStoreUncompressed = await OS.File.read(Paths.clean.replace("jsonlz4", "js"), {encoding: "utf-8"});
+ let parsed = JSON.parse(sessionStoreUncompressed);
+
+ // Read the session file with .js extension.
+ let result = await SessionFile.read();
+
+ // Check whether the result is what we wanted.
+ equal(result.origin, "clean");
+ equal(result.useOldExtension, true);
+ Assert.deepEqual(result.parsed, parsed, "result.parsed contains expected data");
+
+ // Initiate a write to ensure we write the compressed version.
+ await SessionFile.write(parsed);
+ await promise_check_exist(Paths.backups, true);
+ await promise_check_exist(Paths.clean, false);
+ await promise_check_exist(Paths.cleanBackup, true);
+ await promise_check_exist(Paths.recovery, true);
+ await promise_check_exist(Paths.recoveryBackup, false);
+ await promise_check_exist(Paths.nextUpgradeBackup, true);
+ // The deprecated $Path.clean should exist.
+ await promise_check_exist(Paths.clean.replace("jsonlz4", "js"), true);
+
+ await promise_check_contents(Paths.recovery, parsed);
+});
+
+add_task(async function test_startup_with_compressed_clean() {
+ let state = {windows: []};
+ let stateString = JSON.stringify(state);
+
+ // Mare sure we have an empty profile dir.
+ await SessionFile.wipe();
+
+ // Populate session files to profile dir.
+ await OS.File.writeAtomic(Paths.clean, stateString, {encoding: "utf-8", compression: "lz4"});
+ await OS.File.makeDir(Paths.backups);
+ await OS.File.writeAtomic(Paths.cleanBackup, stateString, {encoding: "utf-8", compression: "lz4"});
+
+ // Initiate a read.
+ let result = await SessionFile.read();
+
+ // Make sure we read correct session file and its content.
+ equal(result.origin, "clean");
+ equal(result.useOldExtension, false);
+ Assert.deepEqual(state, result.parsed, "result.parsed contains expected data");
+});
+
+add_task(async function test_empty_profile_dir() {
+ // Make sure that we have empty profile dir.
+ await SessionFile.wipe();
+ await promise_check_exist(Paths.backups, false);
+ await promise_check_exist(Paths.clean, false);
+ await promise_check_exist(Paths.cleanBackup, false);
+ await promise_check_exist(Paths.recovery, false);
+ await promise_check_exist(Paths.recoveryBackup, false);
+ await promise_check_exist(Paths.nextUpgradeBackup, false);
+ await promise_check_exist(Paths.backups.replace("jsonlz4", "js"), false);
+ await promise_check_exist(Paths.clean.replace("jsonlz4", "js"), false);
+ await promise_check_exist(Paths.cleanBackup.replace("lz4", ""), false);
+ await promise_check_exist(Paths.recovery.replace("jsonlz4", "js"), false);
+ await promise_check_exist(Paths.recoveryBackup.replace("jsonlz4", "js"), false);
+ await promise_check_exist(Paths.nextUpgradeBackup.replace("jsonlz4", "js"), false);
+
+ // Initiate a read and make sure that we are in empty state.
+ let result = await SessionFile.read();
+ equal(result.origin, "empty");
+ equal(result.noFilesFound, true);
+
+ // Create a state to store.
+ let state = {windows: []};
+ await SessionWorker.post("write", [state, {isFinalWrite: true}]);
+
+ // Check session files are created, but not deprecated ones.
+ await promise_check_exist(Paths.clean, true);
+ await promise_check_exist(Paths.clean.replace("jsonlz4", "js"), false);
+
+ // Check session file' content is correct.
+ await promise_check_contents(Paths.clean, state);
+});