[Fix clojure-emacs#506] Makes display version command return the actual version

`clojure-mode-display-version` displays the correct version (was displaying nil)

also added some tests

Author: Carlos Requena López

CHANGELOG.md

@@ -5,6 +5,7 @@
 ### Bugs fixed
 
 * Dynamic vars whose names contain non-alphanumeric characters are now font-locked correctly.
+* [#506](https://github.com/clojure-emacs/clojure-mode/issues/506): `clojure-mode-display-version` correctly displays the package's version
 
 ## 5.10.0 (2019-01-05)
 

clojure-mode.el

@@ -81,7 +81,10 @@
   :link '(url-link :tag "GitHub" "https://github.com/clojure-emacs/clojure-mode")
   :link '(emacs-commentary-link :tag "Commentary" "clojure-mode"))
 
-(defconst clojure-mode-version (lm-version)
+(defconst clojure-mode-version
+  (let ((thisbuffer (or load-file-name buffer-file-name)))
+    (with-temp-buffer (insert-file-contents thisbuffer)
+                      (lm-version)))
   "The current version of `clojure-mode'.")
 
 (defface clojure-keyword-face

test/clojure-mode-util-test.el

@@ -26,6 +26,10 @@
 (require 'cl-lib)
 (require 'ert)
 
+
+(ert-deftest clojure-mode-version-should-be-non-nil ()
+  (should (not (eq clojure-mode-version nil))))
+
 (let ((project-dir "/home/user/projects/my-project/")
       (clj-file-path "/home/user/projects/my-project/src/clj/my_project/my_ns/my_file.clj")
       (project-relative-clj-file-path "src/clj/my_project/my_ns/my_file.clj")