Don't send empty lines for implicit targets in ERC

* erc.el (erc-send-input-line): Previously, any line typed into a
query or channel buffer without an explicit user-command
handler (meaning most lines), would be sent twice because a trailing
newline (linefeed) would be appended. This has been verified by
checking IRCd server logs. IRCds won't return an error upon receiving
an empty message, but they also won't forward them to channel
subscribers and DM pals.

* erc-tests.el: Add test for erc-process-input-line, which also
indirectly tests erc-send-input-line. It also tests the command
lookup and dispatch facility (bug#50008).

1 files changed, 62 insertions, 0 deletions

diff --git a/test/lisp/erc/erc-tests.el b/test/lisp/erc/erc-tests.el
index 6ed26f68289..685f4e2bea2 100644
--- a/test/lisp/erc/erc-tests.el
+++ b/test/lisp/erc/erc-tests.el
@@ -228,4 +228,66 @@
     (kill-buffer "*erc-protocol*")
     (should-not erc-debug-irc-protocol)))
 
+
+;; The point of this test is to ensure output is handled identically
+;; regardless of whether a command handler is summoned.
+
+(ert-deftest erc-process-input-line ()
+  (let (erc-server-last-sent-time
+        erc-server-flood-queue
+        (orig-erc-cmd-MSG (symbol-function 'erc-cmd-MSG))
+        calls)
+    (with-temp-buffer
+      (cl-letf (((symbol-function 'erc-cmd-MSG)
+                 (lambda (line)
+                   (push line calls)
+                   (funcall orig-erc-cmd-MSG line)))
+                ((symbol-function 'erc-server-buffer)
+                 (lambda () (current-buffer)))
+                ((symbol-function 'erc-server-process-alive)
+                 (lambda () t))
+                ((symbol-function 'erc-server-send-queue)
+                 #'ignore)
+                ((symbol-function 'erc-default-target)
+                 (lambda () "" "#chan")))
+
+        (ert-info ("Dispatch to user command handler")
+
+          (ert-info ("Baseline")
+            (erc-process-input-line "/msg #chan hi\n")
+            (should (equal (pop calls) " #chan hi"))
+            (should (equal (pop erc-server-flood-queue)
+                           '("PRIVMSG #chan :hi\r\n" . utf-8))))
+
+          (ert-info ("Spaces preserved")
+            (erc-process-input-line "/msg #chan hi you\n")
+            (should (equal (pop calls) " #chan hi you"))
+            (should (equal (pop erc-server-flood-queue)
+                           '("PRIVMSG #chan :hi you\r\n" . utf-8))))
+
+          (ert-info ("Empty line honored")
+            (erc-process-input-line "/msg #chan\n")
+            (should (equal (pop calls) " #chan"))
+            (should (equal (pop erc-server-flood-queue)
+                           '("PRIVMSG #chan :\r\n" . utf-8)))))
+
+        (ert-info ("Implicit cmd via `erc-send-input-line-function'")
+
+          (ert-info ("Baseline")
+            (erc-process-input-line "hi")
+            (should (equal (pop erc-server-flood-queue)
+                           '("PRIVMSG #chan :hi\r\n" . utf-8))))
+
+          (ert-info ("Spaces preserved")
+            (erc-process-input-line "hi you")
+            (should (equal (pop erc-server-flood-queue)
+                           '("PRIVMSG #chan :hi you\r\n" . utf-8))))
+
+          (ert-info ("Empty line transmitted without injected-space kludge")
+            (erc-process-input-line "")
+            (should (equal (pop erc-server-flood-queue)
+                           '("PRIVMSG #chan :\r\n" . utf-8))))
+
+          (should-not calls))))))
+
 ;;; erc-tests.el ends here