document how to use buffer-save-without-query

and activate it for tests

close #270

README.md

@@ -229,11 +229,21 @@ You can format your code with:
 - `rustic-format-dwim`   run format on region,file or cargo fmt
 
 Rustic uses the function `rustic-save-some-buffers` for saving buffers
-before compilation. To save buffers automatically, you can change the
-value of `buffer-save-without-query`. In case you prefer using lsp for
+before compilation. In case you prefer using lsp for
 formatting, turn off `rustic-format-on-save` and set
 `rustic-lsp-format`to `t`.
 
+To save buffers automatically, you can change the value of
+`buffer-save-without-query`:
+
+```elisp
+(defun rustic-mode-auto-save-hook ()
+    "Enable auto-saving in rustic-mode buffers."
+    (when buffer-file-name
+      (setq-local buffer-save-without-query t)))
+(add-hook 'rustic-mode-hook 'rustic-mode-auto-save-hook)
+```
+
 Customization:
 
 - `rustic-rustfmt-bin` path to rustfmt executable

test/rustic-compile-test.el

@@ -38,8 +38,7 @@
       (with-current-buffer buffer2
         (write-file file2)
         (insert string))
-      (let ((buffer-save-without-query t))
-        (rustic-save-some-buffers))
+      (rustic-save-some-buffers)
       (sit-for 1)
       (with-current-buffer buffer1
         (should (string= (buffer-string) formatted-string)))

test/test-helper.el

@@ -49,7 +49,6 @@ Emacs shutdown.")
          (dir (rustic-babel-generate-project t))
          (src (concat dir "/src"))
          (file (expand-file-name "main.rs" src))
-         (buffer-save-without-query t)
          (rustic-format-trigger nil))
     (with-current-buffer buffer
       (write-file file)
@@ -105,3 +104,9 @@ list of substrings of `STR' each followed by its face."
     (font-lock-ensure)
     (font-lock-flush)
     (buffer-string)))
+
+(defun rustic-mode-auto-save-hook ()
+    "Enable auto-saving in rustic-mode buffers."
+    (when buffer-file-name
+      (setq-local buffer-save-without-query t)))
+(add-hook 'rustic-mode-hook 'rustic-mode-auto-save-hook)