master 856e0ec: * lisp/vc/diff-mode.el (diff-hunk-text): Test-driven fix for newlines.

[Juri Linkov]

branch: master
commit 856e0ec2f81bfe2f6721369a1df9a26f41e6d1a4
Author: Juri Linkov <juri@linkov.net>
Commit: Juri Linkov <juri@linkov.net>

    * lisp/vc/diff-mode.el (diff-hunk-text): Test-driven fix for newlines.
    
    * lisp/vc/diff-mode.el (diff-hunk-text): Fix handling of newlines
    to cover all test cases according to new test.
    
    * test/lisp/vc/diff-mode-tests.el (diff-mode-test-hunk-text-no-newline):
    New test to cover cases with no newline at end of file.
---
 lisp/vc/diff-mode.el            |  18 +++--
 test/lisp/vc/diff-mode-tests.el | 142 ++++++++++++++++++++++++++++++++++++++++
 2 files changed, 154 insertions(+), 6 deletions(-)

diff --git a/lisp/vc/diff-mode.el b/lisp/vc/diff-mode.el
index 4118a2e..a009339 100644
--- a/lisp/vc/diff-mode.el
+++ b/lisp/vc/diff-mode.el
@@ -1767,20 +1767,26 @@ char-offset in TEXT."
            (delete-region (point-min) keep))
          ;; Remove line-prefix characters, and unneeded lines (unified diffs).
           ;; Also skip lines like "\ No newline at end of file"
-         (let ((kill-chars (list (if destp ?- ?+) ?\\)))
+         (let ((kill-chars (list (if destp ?- ?+) ?\\))
+                curr-char last-char)
            (goto-char (point-min))
            (while (not (eobp))
-             (if (memq (char-after) kill-chars)
+             (setq curr-char (char-after))
+             (if (memq curr-char kill-chars)
                  (delete-region
                   ;; Check for "\ No newline at end of file"
-                  (if (and (eq (char-after) ?\\)
+                  (if (and (eq curr-char ?\\)
+                           (not (eq last-char (if destp ?- ?+)))
                            (save-excursion
-                             (forward-line 1) (eobp)))
-                      (1- (point))
+                             (forward-line 1)
+                             (or (eobp) (and (eq last-char ?-)
+                                             (eq (char-after) ?+)))))
+                      (max (1- (point)) (point-min))
                     (point))
                   (progn (forward-line 1) (point)))
                (delete-char num-pfx-chars)
-               (forward-line 1)))))
+               (forward-line 1))
+             (setq last-char curr-char))))
 
        (let ((text (buffer-substring-no-properties (point-min) (point-max))))
          (if char-offset (cons text (- (point) (point-min))) text))))))
diff --git a/test/lisp/vc/diff-mode-tests.el b/test/lisp/vc/diff-mode-tests.el
index f4e5c89..5bc4ad6 100644
--- a/test/lisp/vc/diff-mode-tests.el
+++ b/test/lisp/vc/diff-mode-tests.el
@@ -203,6 +203,148 @@ youthfulness
           (kill-buffer buf2)
           (delete-directory temp-dir 'recursive))))))
 
+(ert-deftest diff-mode-test-hunk-text-no-newline ()
+  "Check output of `diff-hunk-text' with no newline at end of file."
+
+  ;; First check unified change/remove/add cases with newline
+  (let ((hunk "\
+@@ -1 +1 @@
+-foo
++bar
+"))
+    (should (equal (diff-hunk-text hunk nil nil) "\
+foo
+"))
+    (should (equal (diff-hunk-text hunk t nil) "\
+bar
+")))
+
+  (let ((hunk "\
+@@ -1 +0,0 @@
+-foo
+"))
+    (should (equal (diff-hunk-text hunk nil nil) "\
+foo
+"))
+    (should (equal (diff-hunk-text hunk t nil) "\
+")))
+
+  (let ((hunk "\
+@@ -0,0 +1 @@
++bar
+"))
+    (should (equal (diff-hunk-text hunk nil nil) "\
+"))
+    (should (equal (diff-hunk-text hunk t nil) "\
+bar
+")))
+
+  ;; Check unified change/remove cases with no newline in old file
+  (let ((hunk "\
+@@ -1 +1 @@
+-foo
+\\ No newline at end of file
++bar
+"))
+    (should (equal (diff-hunk-text hunk nil nil) "\
+foo"))
+    (should (equal (diff-hunk-text hunk t nil) "\
+bar
+")))
+
+  (let ((hunk "\
+@@ -1 +0,0 @@
+-foo
+\\ No newline at end of file
+"))
+    (should (equal (diff-hunk-text hunk nil nil) "\
+foo"))
+    (should (equal (diff-hunk-text hunk t nil) "\
+")))
+
+  ;; Check unified change/add cases with no newline in new file
+  (let ((hunk "\
+@@ -1 +1 @@
+-foo
++bar
+\\ No newline at end of file
+"))
+    (should (equal (diff-hunk-text hunk nil nil) "\
+foo
+"))
+    (should (equal (diff-hunk-text hunk t nil) "\
+bar")))
+
+  (let ((hunk "\
+@@ -0,0 +1 @@
++bar
+\\ No newline at end of file
+"))
+    (should (equal (diff-hunk-text hunk nil nil) "\
+"))
+    (should (equal (diff-hunk-text hunk t nil) "\
+bar")))
+
+  ;; Check unified change case with no newline in both old/new file
+  (let ((hunk "\
+@@ -1 +1 @@
+-foo
+\\ No newline at end of file
++bar
+\\ No newline at end of file
+"))
+    (should (equal (diff-hunk-text hunk nil nil) "\
+foo"))
+    (should (equal (diff-hunk-text hunk t nil) "\
+bar")))
+
+  ;; Check context-after unified change case with no newline in both old/new 
file
+  (let ((hunk "\
+@@ -1,2 +1,2 @@
+-foo
++bar
+ baz
+\\ No newline at end of file
+"))
+    (should (equal (diff-hunk-text hunk nil nil) "\
+foo
+baz"))
+    (should (equal (diff-hunk-text hunk t nil) "\
+bar
+baz")))
+
+  (let ((hunk "\
+@@ -1,2 +1,2 @@
+-foo
+-baz
+\\ No newline at end of file
++bar
++baz
+"))
+    (should (equal (diff-hunk-text hunk nil nil) "\
+foo
+baz"))
+    (should (equal (diff-hunk-text hunk t nil) "\
+bar
+baz
+")))
+
+  (let ((hunk "\
+@@ -1,2 +1,2 @@
+-foo
+-baz
++bar
++baz
+\\ No newline at end of file
+"))
+    (should (equal (diff-hunk-text hunk nil nil) "\
+foo
+baz
+"))
+    (should (equal (diff-hunk-text hunk t nil) "\
+bar
+baz"))))
+
 (ert-deftest diff-mode-test-font-lock ()
   "Check font-locking of diff hunks."
   ;; See comments in diff-hunk-file-names about nonascii.