python.el: Fix electric colon behavior

* lisp/progmodes/python.el (python-indent-post-self-insert-function):
Make colon to re-indent only for dedenters, handling
multiline-statements gracefully.

* test/automated/python-tests.el (python-indent-electric-colon-2)
(python-indent-electric-colon-3): New tests.

1 files changed, 33 insertions, 0 deletions

diff --git a/test/automated/python-tests.el b/test/automated/python-tests.el
index f84ded8cad2..d1713ac1851 100644
--- a/test/automated/python-tests.el
+++ b/test/automated/python-tests.el
@@ -740,6 +740,39 @@ def b()
    (python-tests-self-insert ":")
    (should (= (current-indentation) 0))))
 
+(ert-deftest python-indent-electric-colon-2 ()
+  "Test indentation case for dedenter."
+  (python-tests-with-temp-buffer
+   "
+if do:
+    something()
+    else
+"
+   (python-tests-look-at "else")
+   (goto-char (line-end-position))
+   (python-tests-self-insert ":")
+   (should (= (current-indentation) 0))))
+
+(ert-deftest python-indent-electric-colon-3 ()
+  "Test indentation case for multi-line dedenter."
+  (python-tests-with-temp-buffer
+   "
+if do:
+    something()
+    elif (this
+          and
+          that)
+"
+   (python-tests-look-at "that)")
+   (goto-char (line-end-position))
+   (python-tests-self-insert ":")
+   (python-tests-look-at "elif" -1)
+   (should (= (current-indentation) 0))
+   (python-tests-look-at "and")
+   (should (= (current-indentation) 6))
+   (python-tests-look-at "that)")
+   (should (= (current-indentation) 6))))
+
 (ert-deftest python-indent-region-1 ()
   "Test indentation case from Bug#18843."
   (let ((contents "