setting: Allow aliases for some email settings

The keys for setting the username and password for incoming and outgoing
mail are inconsisent: one uses `USERNAME` and `PASSWORD`, the other uses
`USER` and `PASSWD`.

To make things simpler, allow both to be configured by either, thus,
`[mailer].USERNAME` and `[mailer.PASSWORD]` will be aliases for `.USER`
and `.PASSWD`, and similarly, `[email.incoming].USER` and
`[email.incoming].PASSWD` will be aliases for `.USERNAME` and
`.PASSWORD`.

Fixes #3355.

Signed-off-by: Gergely Nagy <forgejo@gergo.csillger.hu>

modules/setting/incoming_email_test.go

@@ -0,0 +1,24 @@
+// Copyright 2024 The Forgejo Authors. All rights reserved.
+// SPDX-License-Identifier: MIT
+
+package setting
+
+import (
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+)
+
+func Test_loadIncomingEmailFrom(t *testing.T) {
+	cfg, _ := NewConfigProviderFromData("")
+	sec := cfg.Section("email.incoming")
+	sec.NewKey("ENABLED", "true")
+	sec.NewKey("USER", "jane.doe@example.com")
+	sec.NewKey("PASSWD", "y0u'll n3v3r gUess th1S!!1")
+	sec.NewKey("REPLY_TO_ADDRESS", "forge+%{token}@example.com")
+
+	loadIncomingEmailFrom(cfg)
+
+	assert.EqualValues(t, "jane.doe@example.com", IncomingEmail.Username)
+	assert.EqualValues(t, "y0u'll n3v3r gUess th1S!!1", IncomingEmail.Password)
+}