Improve robustness of shadowfile.el

* lisp/shadowfile.el (shadow-site-help): New defconst.
(shadow-read-site): Use it.
(shadow-make-fullname, shadow-contract-file-name)
(shadow-define-literal-group): Handle errors more robust.  (Bug#49596)

* test/lisp/shadowfile-tests.el (shadow-test06-literal-groups):
Extend test.

1 files changed, 23 insertions, 1 deletions

diff --git a/test/lisp/shadowfile-tests.el b/test/lisp/shadowfile-tests.el
index c571dc3e14b..1ab539f3e42 100644
--- a/test/lisp/shadowfile-tests.el
+++ b/test/lisp/shadowfile-tests.el
@@ -664,7 +664,29 @@ guaranteed by the originator of a cluster definition."
 	  (should (member (format "/%s:%s" cluster2 (file-local-name file2))
                           (car shadow-literal-groups)))
           ;; Bug#49596.
-	  (should (member (concat primary file1) (car shadow-literal-groups))))
+	  (should (member (concat primary file1) (car shadow-literal-groups)))
+
+          ;; Error handling.
+          (setq shadow-literal-groups nil)
+          ;; There's no `buffer-file-name'.
+          (with-temp-buffer
+            (call-interactively #'shadow-define-literal-group)
+            (set-buffer-modified-p nil))
+          (should-not shadow-literal-groups)
+	  ;; Define an empty literal group.
+	  (setq mocked-input `(,(kbd "RET")))
+	  (with-temp-buffer
+            (set-visited-file-name file1)
+	    (call-interactively #'shadow-define-literal-group)
+            (set-buffer-modified-p nil))
+          (should-not shadow-literal-groups)
+          ;; Use a non-existing site name.
+	  (setq mocked-input `("foo" ,(kbd "RET")))
+	  (with-temp-buffer
+            (set-visited-file-name file1)
+	    (call-interactively #'shadow-define-literal-group)
+            (set-buffer-modified-p nil))
+          (should-not shadow-literal-groups))
 
       ;; Cleanup.
       (shadow--tests-cleanup))))