Add newer Emacs versions to tests

On my system whenever I run the tests without specifying an initial branch name,
I get a lot of messages about setting the default branch name globally. This is
just noise for these tests, so this specifies a branch name manually to make it
go away.

The name ‘gac-test’ was chosen to make it clear that we're dealing with a
repository created specifically for ‘git-auto-commit-mode’ in case somehow a
repository gets left behind.

.github/workflows/test.yml

@@ -10,6 +10,8 @@ jobs:
       matrix:
         emacs_version:
           - '26.3'
+          - '27.2'
+          - '28.2'
           - 'snapshot'
         include:
           - emacs_version: 'snapshot'

README.org

@@ -114,3 +114,23 @@
     A boolean value indicating whether to display the commit summary message,
     which is usually displayed in the minibuffer. The default is ~nil~, meaning
     that the summary would be displayed on every commit.
+
+
+  To set any of these options, you can:
+
+  - Use the customization interface (~M-x customize-group git-auto-commit-mode~).
+  - Set the defaults in your Emacs initialization file using:
+    #+begin_src emacs-lisp
+      (setq-default gac-ask-for-summary-p t)
+    #+end_src
+  - Set values in a hook:
+    #+begin_src emacs-lisp
+      (defun set-my-settings ()
+        (setq gac-automatically-push-p t))
+
+      (add-hook 'org-mode-hook 'set-my-settings)
+    #+end_src
+  - Set values in a ~.dir-locals.el~ (see [[https://www.gnu.org/software/emacs/manual/html_node/emacs/Directory-Variables.html#Directory-Variables][Per-Directory Local Variables]]):
+    #+begin_src emacs-lisp
+      ((nil . ((gac-shell-and . " ; and "))))
+    #+end_src

tests/git-auto-commit-mode-tests.el

@@ -27,6 +27,10 @@
 (require 'buttercup)
 (require 'git-auto-commit-mode)
 
+(defun git-auto-commit-mode-tests--get-last-commit-message ()
+  "Get the last commit message from git."
+  (shell-command-to-string "git log --format=format:%s"))
+
 (describe "In a git repository"
   :var (temp-dir current-directory)
 
@@ -34,7 +38,7 @@
     (setq temp-dir (make-temp-file "gac-" t)
           current-directory default-directory
           default-directory temp-dir)
-    (shell-command "git init")
+    (shell-command "git init --initial-branch=gac-test")
     (shell-command "git config user.email user@example.com")
     (shell-command "git config user.name \"User Example\""))
 
@@ -55,7 +59,7 @@
             (insert "test")
             (save-buffer))
 
-          (expect (shell-command-to-string "git log --format=format:%s")
+          (expect (git-auto-commit-mode-tests--get-last-commit-message)
                   :to-match (rx string-start "test" string-end)))))
 
     (describe "When ‘gac-automatically-add-new-files’ is nil"
@@ -68,7 +72,7 @@
             (insert "test")
             (save-buffer))
 
-          (expect (shell-command-to-string "git log --format=format:%s")
+          (expect (git-auto-commit-mode-tests--get-last-commit-message)
                   :not :to-match (rx string-start "test" string-end))))))
 
   (describe "Getting a relative path"
@@ -140,7 +144,45 @@
           (save-buffer))
 
         (expect (gac-relative-file-name temp-file)
-                :to-equal "[test-test.txt")))))
+                :to-equal "[test-test.txt"))))
+
+  (describe "Getting a commit message"
+    (it "should default to the relative file name"
+      (let* ((temp-file (expand-file-name "test.txt" temp-dir))
+             (buffer (find-file-noselect temp-file)))
+        (with-current-buffer buffer
+          (git-auto-commit-mode)
+          (insert "test")
+          (save-buffer))
+
+        (expect (git-auto-commit-mode-tests--get-last-commit-message)
+                :to-equal "test.txt")))
+
+    (it "should use the message specified in ‘gac-default-message’"
+      (let* ((temp-file (expand-file-name "test.txt" temp-dir))
+             (buffer (find-file-noselect temp-file))
+             (gac-default-message "I made a commit!"))
+        (with-current-buffer buffer
+          (git-auto-commit-mode)
+          (insert "test")
+          (save-buffer))
+
+        (expect (git-auto-commit-mode-tests--get-last-commit-message)
+                :to-equal "I made a commit!")))
+
+    (it "should use the function result if ‘gac-default-message’ is a function"
+      (let* ((temp-file (expand-file-name "test.txt" temp-dir))
+             (buffer (find-file-noselect temp-file))
+             (gac-default-message
+              (lambda (f)
+                (concat "wip " (gac-relative-file-name f)))))
+        (with-current-buffer buffer
+          (git-auto-commit-mode)
+          (insert "test")
+          (save-buffer))
+
+        (expect (git-auto-commit-mode-tests--get-last-commit-message)
+                :to-equal "wip test.txt")))))
 
 (provide 'git-auto-commit-mode-tests)
 ;;; git-auto-commit-mode-tests.el ends here