Bug 1897924 - Default to SMTP if we can't figure out the type of an outgoing server. r=mkmelin

Differential Revision: https://phabricator.services.mozilla.com/D214002

--HG--
extra : amend_source : ef6a83142f9b5fa7d78e9bb1b089901cc54ac9aa

mailnews/compose/src/OutgoingServerService.sys.mjs

@@ -241,11 +241,15 @@ export class OutgoingServerService {
    * @returns {nsIMsgOutgoingServer}
    */
   _keyToServer(key) {
-    // We're intentionally not setting a default value, because if we're not
-    // sure of the type we want to fail early, rather than e.g. halfway through
-    // trying to configure the server with incorrect settings.
+    // Ideally we should be failing early if we can't figure out the type,
+    // because we might be trying to configure the server for the wrong
+    // protocol. However, We might be currently migrating an old profile that
+    // predates this pref being introduced, in which case we'll try to read this
+    // pref before the profile migration code has had a chance to set it. In
+    // which case, it's likely safe to assume the server's type is SMTP.
     const serverType = Services.prefs.getCharPref(
-      `mail.smtpserver.${key}.type`
+      `mail.smtpserver.${key}.type`,
+      "smtp"
     );
 
     const server = Cc[OUTGOING_CONTRACT_ID_PREFIX + serverType].createInstance(

mailnews/compose/test/unit/test_smtpServer.js

@@ -5,6 +5,26 @@
  * Tests for the SMTP implementation of nsIMsgOutgoingServer.
  */
 
+/**
+ * Test that, if the outgoing server service does not have a type for the
+ * server, it defaults to instantiating the SMTP implementation.
+ */
+add_task(async function test_default_server_type() {
+  // Add a new server to the outgoing server service's list. Note that we don't
+  // set any property - including a type - on this new server.
+  Services.prefs.setCharPref("mail.smtpservers", "smtp1");
+
+  // Get the new server from the service (and make sure the operation doesn't
+  // throw, which would happen if we don't have a default value).
+  const server = MailServices.outgoingServer.getServerByKey("smtp1");
+
+  // Check that the service correctly defaulted to the SMTP implementation.
+  Assert.equal(server.type, "smtp");
+
+  // Remove the server from the service to avoid any side-effect.
+  MailServices.outgoingServer.deleteServer(server);
+});
+
 /**
  * Test that cached server password is cleared when password storage changed.
  */