Bug 1886614 - Write a marionette test for the BackupService.createBackup method. r=backup-reviewers,kpatenio

This test can be run via:

./mach marionette-test browser/components/backup/test/marionette/test_backup.py

This also makes it so that BackupResource.copySqliteDatabases does not throw if
one of the passed in database files doesn't exist - it'll just ignore it and
move on. This required me to update some tests in order to create some fake
SQLite databases to ensure that the fake Sqlite connection was made and the
backup stub was called for the SQLite databases being copied.

Finally, this also fixes something I noticed - some of our BackupResource's
weren't returning null or objects as their ManifestEntry. This fixes that
and adds tests to cover that case.

Differential Revision: https://phabricator.services.mozilla.com/D207811

browser/components/backup/BackupService.sys.mjs

@@ -146,6 +146,12 @@ export class BackupService {
     }
   }
 
+  /**
+   * @typedef {object} CreateBackupResult
+   * @property {string} stagingPath
+   *   The staging path for where the backup was created.
+   */
+
   /**
    * Create a backup of the user's profile.
    *
@@ -154,13 +160,15 @@ export class BackupService {
    * @param {string} [options.profilePath=PathUtils.profileDir]
    *   The path to the profile to backup. By default, this is the current
    *   profile.
-   * @returns {Promise<undefined>}
+   * @returns {Promise<CreateBackupResult|null>}
+   *   A promise that resolves to an object containing the path to the staging
+   *   folder where the backup was created, or null if the backup failed.
    */
   async createBackup({ profilePath = PathUtils.profileDir } = {}) {
     // createBackup does not allow re-entry or concurrent backups.
     if (this.#backupInProgress) {
       lazy.logConsole.warn("Backup attempt already in progress");
-      return;
+      return null;
     }
 
     this.#backupInProgress = true;
@@ -204,11 +212,19 @@ export class BackupService {
             resourcePath,
             profilePath
           );
-          lazy.logConsole.debug(
-            `Backup of resource with key ${resourceClass.key} completed`,
-            manifestEntry
-          );
-          manifest.resources[resourceClass.key] = manifestEntry;
+
+          if (manifestEntry === undefined) {
+            lazy.logConsole.error(
+              `Backup of resource with key ${resourceClass.key} returned undefined
+              as its ManifestEntry instead of null or an object`
+            );
+          } else {
+            lazy.logConsole.debug(
+              `Backup of resource with key ${resourceClass.key} completed`,
+              manifestEntry
+            );
+            manifest.resources[resourceClass.key] = manifestEntry;
+          }
         } catch (e) {
           lazy.logConsole.error(
             `Failed to backup resource: ${resourceClass.key}`,
@@ -246,7 +262,12 @@ export class BackupService {
       );
       await IOUtils.writeJSON(manifestPath, manifest);
 
-      await this.#finalizeStagingFolder(stagingPath);
+      let renamedStagingPath = await this.#finalizeStagingFolder(stagingPath);
+      lazy.logConsole.log(
+        "Wrote backup to staging directory at ",
+        renamedStagingPath
+      );
+      return { stagingPath: renamedStagingPath };
     } finally {
       this.#backupInProgress = false;
     }
@@ -280,7 +301,10 @@ export class BackupService {
    * The ISO date string should be formatted from YYYY-MM-DDTHH:mm:ss.sssZ to YYYY-MM-DDTHH-mm-ssZ
    *
    * @param {string} stagingPath
-   *  The path to the populated staging folder.
+   *   The path to the populated staging folder.
+   * @returns {Promise<string|null>}
+   *   The path to the renamed staging folder, or null if the stagingPath was
+   *   not pointing to a valid folder.
    */
   async #finalizeStagingFolder(stagingPath) {
     if (!(await IOUtils.exists(stagingPath))) {
@@ -288,7 +312,7 @@ export class BackupService {
       lazy.logConsole.error(
         `Failed to finalize staging folder. Cannot find ${stagingPath}.`
       );
-      return;
+      return null;
     }
 
     try {
@@ -319,10 +343,12 @@ export class BackupService {
           });
         }
       }
+      return renamedBackupPath;
     } catch (e) {
       lazy.logConsole.error(
         `Something went wrong while finalizing the staging folder. ${e}`
       );
+      throw e;
     }
   }