Refactor lisp eval result printing

* lisp/simple.el (eval-expression-print-format): Don't check
`standard-output' or `current-prefix-arg'.
(eval-expression-get-print-arguments): New function, centralizes
decision about how to print results of `eval-expression' and
`eval-last-sexp'.
(eval-expression):
* lisp/progmodes/elisp-mode.el (elisp--eval-last-sexp-print-value):
Use it.

2 files changed, 50 insertions, 10 deletions

diff --git a/test/lisp/progmodes/elisp-mode-tests.el b/test/lisp/progmodes/elisp-mode-tests.el
index 93c428b2d2b..5edb590b1e5 100644
--- a/test/lisp/progmodes/elisp-mode-tests.el
+++ b/test/lisp/progmodes/elisp-mode-tests.el
@@ -114,6 +114,24 @@
       (should (member "backup-buffer" comps))
       (should-not (member "backup-inhibited" comps)))))
 
+;;; eval-last-sexp
+
+(ert-deftest eval-last-sexp-print-format-sym ()
+  (with-temp-buffer
+    (let ((current-prefix-arg '(4)))
+      (erase-buffer) (insert "t")
+      (call-interactively #'eval-last-sexp)
+      (should (equal (buffer-string) "tt")))))
+
+(ert-deftest eval-last-sexp-print-format-sym-echo ()
+  ;; We can only check the echo area when running interactive.
+  (skip-unless (not noninteractive))
+  (with-temp-buffer
+    (let ((current-prefix-arg nil))
+      (erase-buffer) (insert "t") (message nil)
+      (call-interactively #'eval-last-sexp)
+      (should (equal (current-message) "t")))))
+
 ;;; xref
 
 (defun xref-elisp-test-descr-to-target (xref)
diff --git a/test/lisp/simple-tests.el b/test/lisp/simple-tests.el
index f4849c4b21d..b74e28ccaf1 100644
--- a/test/lisp/simple-tests.el
+++ b/test/lisp/simple-tests.el
@@ -20,6 +20,7 @@
 ;;; Code:
 
 (require 'ert)
+(eval-when-compile (require 'cl-lib))
 
 (defmacro simple-test--dummy-buffer (&rest body)
   (declare (indent 0)
@@ -35,6 +36,8 @@
              (buffer-substring (point) (point-max))))))
 
 
+
+;;; `transpose-sexps'
 (defmacro simple-test--transpositions (&rest body)
   (declare (indent 0)
            (debug t))
@@ -46,6 +49,13 @@
      (cons (buffer-substring (point-min) (point))
            (buffer-substring (point) (point-max)))))
 
+;;; Transposition with negative args (bug#20698, bug#21885)
+(ert-deftest simple-transpose-subr ()
+  (should (equal (simple-test--transpositions (transpose-sexps -1))
+                 '("(s1) (s2) (s4)" . " (s3) (s5)")))
+  (should (equal (simple-test--transpositions (transpose-sexps -2))
+                 '("(s1) (s4)" . " (s2) (s3) (s5)"))))
+
 
 ;;; `newline'
 (ert-deftest newline ()
@@ -239,8 +249,8 @@
       (should (equal ?\s (char-syntax ?\f)))
       (should (equal ?\s (char-syntax ?\n))))))
 
-
-;;; auto-boundary tests
+
+;;; undo auto-boundary tests
 (ert-deftest undo-auto-boundary-timer ()
   (should
    undo-auto-current-boundary-timer))
@@ -269,14 +279,6 @@
      (insert "hello")
      (undo-auto--boundaries 'test))))
 
-;;; Transposition with negative args (bug#20698, bug#21885)
-(ert-deftest simple-transpose-subr ()
-  (should (equal (simple-test--transpositions (transpose-sexps -1))
-                 '("(s1) (s2) (s4)" . " (s3) (s5)")))
-  (should (equal (simple-test--transpositions (transpose-sexps -2))
-                 '("(s1) (s4)" . " (s2) (s3) (s5)"))))
-
-
 ;; Test for a regression introduced by undo-auto--boundaries changes.
 ;; https://lists.gnu.org/archive/html/emacs-devel/2015-11/msg01652.html
 (defun undo-test-kill-c-a-then-undo ()
@@ -374,5 +376,25 @@ See Bug#21722."
        (undo)
        (point)))))
 
+
+;;; `eval-expression'
+
+(ert-deftest eval-expression-print-format-sym ()
+  (with-temp-buffer
+    (cl-letf (((symbol-function 'read--expression) (lambda (&rest _) t)))
+      (let ((current-prefix-arg '(4)))
+        (call-interactively #'eval-expression)
+        (should (equal (buffer-string) "t"))))))
+
+(ert-deftest eval-expression-print-format-sym-echo ()
+  ;; We can only check the echo area when running interactive.
+  (skip-unless (not noninteractive))
+  (with-temp-buffer
+    (cl-letf (((symbol-function 'read--expression) (lambda (&rest _) t)))
+      (let ((current-prefix-arg nil))
+        (message nil)
+        (call-interactively #'eval-expression)
+        (should (equal (current-message) "t"))))))
+
 (provide 'simple-test)
 ;;; simple-test.el ends here