Fix a few minor compilation and Checkdoc warnings.

* test/src/emacs-module-tests.el: Add package name and standard
sections.
(multiply-string): Add a docstring.

test/src/emacs-module-tests.el

@@ -1,4 +1,4 @@
-;;; Test GNU Emacs modules.  -*- lexical-binding: t; -*-
+;;; emacs-module-tests --- Test GNU Emacs modules.  -*- lexical-binding: t; -*-
 
 ;; Copyright 2015-2019 Free Software Foundation, Inc.
 
@@ -17,6 +17,14 @@
 ;; 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:
+
+;; Unit tests for the dynamic module facility.  See Info node `(elisp)
+;; Writing Dynamic Modules'.  These tests make use of a small test
+;; module in test/data/emacs-module.
+
+;;; Code:
+
 (require 'cl-lib)
 (require 'ert)
 (require 'help-fns)
@@ -137,6 +145,7 @@ changes."
 ;;
 
 (defun multiply-string (s n)
+  "Return N copies of S concatenated together."
   (let ((res ""))
     (dotimes (i n)
       (setq res (concat res s)))