Fixed dedent for tab indent.

rest_framework/utils/formatting.py

@@ -32,23 +32,18 @@ def dedent(content):
     unindented text on the initial line.
     """
     content = force_text(content)
-    whitespace_counts = [
-        len(line) - len(line.lstrip(' '))
-        for line in content.splitlines()[1:] if line.lstrip()
-    ]
-    tab_counts = [
-        len(line) - len(line.lstrip('\t'))
-        for line in content.splitlines()[1:] if line.lstrip()
-    ]
+    lines = [line for line in content.splitlines()[1:] if line.lstrip()]
 
     # unindent the content if needed
+    if lines:
+        whitespace_counts = min([len(line) - len(line.lstrip(' ')) for line in lines])
+        tab_counts = min([len(line) - len(line.lstrip('\t')) for line in lines])
         if whitespace_counts:
-        whitespace_pattern = '^' + (' ' * min(whitespace_counts))
+            whitespace_pattern = '^' + (' ' * whitespace_counts)
             content = re.sub(re.compile(whitespace_pattern, re.MULTILINE), '', content)
         elif tab_counts:
-        whitespace_pattern = '^' + ('\t' * min(whitespace_counts))
+            whitespace_pattern = '^' + ('\t' * tab_counts)
             content = re.sub(re.compile(whitespace_pattern, re.MULTILINE), '', content)
-
     return content.strip()
 
 

tests/test_description.py

@@ -124,4 +124,8 @@ class TestViewNamesAndDescriptions(TestCase):
 
 
 def test_dedent_tabs():
-    assert dedent("\tfirst string\n\n\tsecond string") == 'first string\n\n\tsecond string'
+    result = 'first string\n\nsecond string'
+    assert dedent("    first string\n\n    second string") == result
+    assert dedent("first string\n\n    second string") == result
+    assert dedent("\tfirst string\n\n\tsecond string") == result
+    assert dedent("first string\n\n\tsecond string") == result