python.el: Fix python-shell-buffer-substring on indented code

Fixes: debbugs:21086

* lisp/progmodes/python.el (python-shell-buffer-substring):
Respect current line indentation when calculating string.

* test/automated/python-tests.el
(python-shell-buffer-substring-10)
(python-shell-buffer-substring-11)
(python-shell-buffer-substring-12): New tests.

2 files changed, 68 insertions, 10 deletions

diff --git a/lisp/progmodes/python.el b/lisp/progmodes/python.el
index fbe5b8b0743..abae8aff47b 100644
--- a/lisp/progmodes/python.el
+++ b/lisp/progmodes/python.el
@@ -2986,29 +2986,32 @@ the python shell:
      coding cookie is added.
   4. Wraps indented regions under an \"if True:\" block so the
      interpreter evaluates them correctly."
-  (let* ((substring (buffer-substring-no-properties start end))
+  (let* ((start (save-excursion
+                  ;; Normalize start to the line beginning position.
+                  (goto-char start)
+                  (line-beginning-position)))
+         (substring (buffer-substring-no-properties start end))
          (starts-at-point-min-p (save-restriction
                                   (widen)
                                   (= (point-min) start)))
          (encoding (python-info-encoding))
+         (toplevel-p (zerop (save-excursion
+                              (goto-char start)
+                              (python-util-forward-comment 1)
+                              (current-indentation))))
          (fillstr (when (not starts-at-point-min-p)
                     (concat
                      (format "# -*- coding: %s -*-\n" encoding)
                      (make-string
                       ;; Subtract 2 because of the coding cookie.
-                      (- (line-number-at-pos start) 2) ?\n))))
-         (toplevel-block-p (save-excursion
-                             (goto-char start)
-                             (or (zerop (line-number-at-pos start))
-                                 (progn
-                                   (python-util-forward-comment 1)
-                                   (zerop (current-indentation)))))))
+                      (- (line-number-at-pos start) 2) ?\n)))))
     (with-temp-buffer
       (python-mode)
-      (if fillstr (insert fillstr))
+      (when fillstr
+        (insert fillstr))
       (insert substring)
       (goto-char (point-min))
-      (when (not toplevel-block-p)
+      (when (not toplevel-p)
         (insert "if True:")
         (delete-region (point) (line-end-position)))
       (when nomain
diff --git a/test/automated/python-tests.el b/test/automated/python-tests.el
index e792b0f1a1a..30b1b480a25 100644
--- a/test/automated/python-tests.el
+++ b/test/automated/python-tests.el
@@ -3276,6 +3276,61 @@ class Foo(models.Model):
 
 "))))
 
+(ert-deftest python-shell-buffer-substring-10 ()
+  "Check substring from partial block."
+  (python-tests-with-temp-buffer
+   "
+def foo():
+    print ('a')
+"
+   (should (string= (python-shell-buffer-substring
+                     (python-tests-look-at "print ('a')")
+                     (point-max))
+                    "if True:
+
+    print ('a')
+"))))
+
+(ert-deftest python-shell-buffer-substring-11 ()
+  "Check substring from partial block and point within indentation."
+  (python-tests-with-temp-buffer
+   "
+def foo():
+    print ('a')
+"
+   (should (string= (python-shell-buffer-substring
+                     (progn
+                       (python-tests-look-at "print ('a')")
+                       (backward-char 1)
+                       (point))
+                     (point-max))
+                    "if True:
+
+    print ('a')
+"))))
+
+(ert-deftest python-shell-buffer-substring-12 ()
+  "Check substring from partial block and point in whitespace."
+  (python-tests-with-temp-buffer
+   "
+def foo():
+
+        # Whitespace
+
+    print ('a')
+"
+   (should (string= (python-shell-buffer-substring
+                     (python-tests-look-at "# Whitespace")
+                     (point-max))
+                    "if True:
+
+
+        # Whitespace
+
+    print ('a')
+"))))
+
+
 
 ;;; Shell completion