Issue 11747: Fix output format for context diffs.

1 files changed, 64 insertions, 1 deletions

diff --git a/Lib/test/test_difflib.py b/Lib/test/test_difflib.py
index 852aae9b31e..dc2abe874af 100644
--- a/Lib/test/test_difflib.py
+++ b/Lib/test/test_difflib.py
@@ -159,10 +159,73 @@ class TestSFpatches(unittest.TestCase):
         difflib.SequenceMatcher(None, old, new).get_opcodes()
 
 
+class TestOutputFormat(unittest.TestCase):
+    def test_tab_delimiter(self):
+        args = ['one', 'two', 'Original', 'Current',
+            '2005-01-26 23:30:50', '2010-04-02 10:20:52']
+        ud = difflib.unified_diff(*args, lineterm='')
+        self.assertEqual(list(ud)[0:2], [
+                           "--- Original\t2005-01-26 23:30:50",
+                           "+++ Current\t2010-04-02 10:20:52"])
+        cd = difflib.context_diff(*args, lineterm='')
+        self.assertEqual(list(cd)[0:2], [
+                           "*** Original\t2005-01-26 23:30:50",
+                           "--- Current\t2010-04-02 10:20:52"])
+
+    def test_no_trailing_tab_on_empty_filedate(self):
+        args = ['one', 'two', 'Original', 'Current']
+        ud = difflib.unified_diff(*args, lineterm='')
+        self.assertEqual(list(ud)[0:2], ["--- Original", "+++ Current"])
+
+        cd = difflib.context_diff(*args, lineterm='')
+        self.assertEqual(list(cd)[0:2], ["*** Original", "--- Current"])
+
+    def test_range_format_unified(self):
+        # Per the diff spec at http://www.unix.org/single_unix_specification/
+        spec = '''\
+           Each <range> field shall be of the form:
+             %1d", <beginning line number>  if the range contains exactly one line,
+           and:
+            "%1d,%1d", <beginning line number>, <number of lines> otherwise.
+           If a range is empty, its beginning line number shall be the number of
+           the line just before the range, or 0 if the empty range starts the file.
+        '''
+        fmt = difflib._format_range_unified
+        self.assertEqual(fmt(3,3), '3,0')
+        self.assertEqual(fmt(3,4), '4')
+        self.assertEqual(fmt(3,5), '4,2')
+        self.assertEqual(fmt(3,6), '4,3')
+        self.assertEqual(fmt(0,0), '0,0')
+
+    def test_range_format_context(self):
+        # Per the diff spec at http://www.unix.org/single_unix_specification/
+        spec = '''\
+           The range of lines in file1 shall be written in the following format
+           if the range contains two or more lines:
+               "*** %d,%d ****\n", <beginning line number>, <ending line number>
+           and the following format otherwise:
+               "*** %d ****\n", <ending line number>
+           The ending line number of an empty range shall be the number of the preceding line,
+           or 0 if the range is at the start of the file.
+
+           Next, the range of lines in file2 shall be written in the following format
+           if the range contains two or more lines:
+               "--- %d,%d ----\n", <beginning line number>, <ending line number>
+           and the following format otherwise:
+               "--- %d ----\n", <ending line number>
+        '''
+        fmt = difflib._format_range_context
+        self.assertEqual(fmt(3,3), '3')
+        self.assertEqual(fmt(3,4), '4')
+        self.assertEqual(fmt(3,5), '4,5')
+        self.assertEqual(fmt(3,6), '4,6')
+        self.assertEqual(fmt(0,0), '0')
+
+
 def test_main():
     difflib.HtmlDiff._default_prefix = 0
     Doctests = doctest.DocTestSuite(difflib)
-    run_unittest(TestSFpatches, TestSFbugs, Doctests)
+    run_unittest(TestSFpatches, TestSFbugs, Doctests, TestOutputFormat)
 
 if __name__ == '__main__':
     test_main()