* lisp/emacs-lisp/lisp-mode.el (indent-sexp): Simplify.

* test/lisp/emacs-lisp/lisp-mode-tests.el (indent-sexp):
(indent-subsexp, indent-sexp-in-string): New tests.

test/lisp/emacs-lisp/lisp-mode-tests.el

@@ -0,0 +1,94 @@
+;;; lisp-mode-tests.el --- Test Lisp editing commands  -*- lexical-binding: t; -*-
+
+;; Copyright (C) 2017 Free Software Foundation, Inc.
+
+;; 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 <http://www.gnu.org/licenses/>.
+
+;;; Code:
+
+(require 'ert)
+(require 'cl-lib)
+(require 'lisp-mode)
+
+(ert-deftest indent-sexp ()
+  "Test basics of \\[indent-sexp]."
+  (with-temp-buffer
+    (insert "\
+\(a
+ (prog1
+     (prog1
+         1
+       2)
+   2)
+ (1
+  \"string
+noindent\" (\"string2
+noindent\" 3
+4)
+  2)                                    ; comment
+ ;; comment
+ b)")
+    (goto-char (point-min))
+    (let ((indent-tabs-mode nil)
+          (correct (buffer-string)))
+      (dolist (mode '(fundamental-mode emacs-lisp-mode))
+        (funcall mode)
+        (indent-sexp)
+        ;; Don't mess up correctly indented code.
+        (should (string= (buffer-string) correct))
+        ;; Correctly add indentation.
+        (save-excursion
+          (while (not (eobp))
+            (delete-horizontal-space)
+            (forward-line)))
+        (indent-sexp)
+        (should (equal (buffer-string) correct))
+        ;; Correctly remove indentation.
+        (save-excursion
+          (let ((n 0))
+            (while (not (eobp))
+              (unless (looking-at "noindent")
+                (insert (make-string n ?\s)))
+              (cl-incf n)
+              (forward-line))))
+        (indent-sexp)
+        (should (equal (buffer-string) correct))))))
+
+(ert-deftest indent-subsexp ()
+  "Make sure calling `indent-sexp' inside a sexp works."
+  (with-temp-buffer
+    (insert "\
+\(d1 xx
+    (d2 yy
+	zz)
+    11)")
+    (let ((correct (buffer-string)))
+      (search-backward "d2")
+      (up-list -1)
+      (indent-sexp)
+      (should (equal (buffer-string) correct)))))
+
+(ert-deftest indent-sexp-in-string ()
+  "Make sure calling `indent-sexp' inside a string works."
+  ;; See https://debbugs.gnu.org/cgi/bugreport.cgi?bug=21343.
+  (with-temp-buffer
+    (emacs-lisp-mode)
+    (insert "\";\"")
+    (let ((correct (buffer-string)))
+      (search-backward ";")
+      (indent-sexp)
+      (should (equal (buffer-string) correct)))))
+
+(provide 'lisp-mode-tests)
+;;; lisp-mode-tests.el ends here