Add tests for list-threads and the *Threads* buffer

* test/lisp/thread-tests.el: New file.

test/lisp/thread-tests.el

@@ -0,0 +1,96 @@
+;;; thread-tests.el --- Test suite for thread.el  -*- lexical-binding: t; -*-
+
+;; Copyright (C) 2018 Free Software Foundation, Inc.
+
+;; Author: Gemini Lasswell <gazally@runbox.com>
+;; Keywords: threads
+
+;; This file is part of GNU Emacs.
+
+;; GNU Emacs is free software: you can redistribute it and/or modify
+;; it under the terms of the GNU General Public License as published by
+;; the Free Software Foundation, either version 3 of the License, or
+;; (at your option) any later version.
+
+;; GNU Emacs is distributed in the hope that it will be useful,
+;; but WITHOUT ANY WARRANTY; without even the implied warranty of
+;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+;; GNU General Public License for more details.
+
+;; You should have received a copy of the GNU General Public License
+;; along with GNU Emacs.  If not, see <https://www.gnu.org/licenses/>.
+
+;;; Commentary:
+
+
+;;; Code:
+
+(require 'ert)
+(require 'thread)
+
+;; Declare the functions used here in case Emacs has been configured
+;; --without-threads.
+(declare-function make-mutex "thread.c" (&optional name))
+(declare-function mutex-lock "thread.c" (mutex))
+(declare-function mutex-unlock "thread.c" (mutex))
+(declare-function make-thread "thread.c" (function &optional name))
+(declare-function thread-join "thread.c" (thread))
+(declare-function thread-yield "thread.c" ())
+
+(defvar thread-tests-flag)
+(defvar thread-tests-mutex (when (featurep 'threads) (make-mutex "mutex1")))
+
+(defun thread-tests--thread-function ()
+  (setq thread-tests-flag t)
+  (with-mutex thread-tests-mutex
+    (sleep-for 0.01)))
+
+(ert-deftest thread-tests-thread-list-send-error ()
+  "A thread can be sent an error signal from the *Thread List* buffer."
+  (skip-unless (featurep 'threads))
+  (cl-letf (((symbol-function 'y-or-n-p) (lambda (_prompt) t)))
+    (with-mutex thread-tests-mutex
+      (setq thread-tests-flag nil)
+      (let ((thread (make-thread #'thread-tests--thread-function
+                                 "thread-tests-wait")))
+        (while (not thread-tests-flag)
+          (thread-yield))
+        (list-threads)
+        (goto-char (point-min))
+        (re-search-forward
+         "^thread-tests.+[[:blank:]]+Blocked[[:blank:]]+.+mutex1.+?")
+        (thread-list-send-error-signal)
+        (should-error (thread-join thread))
+        (list-threads)
+        (goto-char (point-min))
+        (should-error (re-search-forward "thread-tests"))))))
+
+(ert-deftest thread-tests-thread-list-show-backtrace ()
+  "Show a backtrace for another thread from the *Thread List* buffer."
+  (skip-unless (featurep 'threads))
+  (let (thread)
+    (with-mutex thread-tests-mutex
+      (setq thread-tests-flag nil)
+      (setq thread
+            (make-thread #'thread-tests--thread-function "thread-tests-back"))
+      (while (not thread-tests-flag)
+        (thread-yield))
+      (list-threads)
+      (goto-char (point-min))
+      (re-search-forward
+       "^thread-tests.+[[:blank:]]+Blocked[[:blank:]]+.+mutex1.+?")
+      (thread-list-pop-to-backtrace)
+      (goto-char (point-min))
+      (re-search-forward "thread-tests-back")
+      (re-search-forward "mutex-lock")
+      (re-search-forward "thread-tests--thread-function"))
+    (thread-join thread)))
+
+(ert-deftest thread-tests-list-threads-error-when-not-configured ()
+  "Signal an error running `list-threads' if threads are not configured."
+  (skip-unless (not (featurep 'threads)))
+  (should-error (list-threads)))
+
+(provide 'thread-tests)
+
+;;; thread-tests.el ends here