Fix #194: a file path could have its prefix twice.

Author: nedbat

CHANGES.txt

@@ -21,6 +21,9 @@ Version 3.5.3b1
 - Optimized .pyo files may not have been handled correctly, `issue 195`_.
   Thanks, Marius Gedminas.
 
+- Certain unusually named file paths could have been mangled during reporting,
+  `issue 194`_.  Thanks, Marius Gedminas.
+
 - Try to do a better job of the impossible task of detecting when we can't
   build the C extension, fixing `issue 183`_.
 
@@ -29,6 +32,7 @@ Version 3.5.3b1
 .. _issue 82: https://bitbucket.org/ned/coveragepy/issue/82/tokenerror-when-generating-html-report
 .. _issue 179: https://bitbucket.org/ned/coveragepy/issue/179/htmlreporter-fails-when-source-file-is
 .. _issue 183: https://bitbucket.org/ned/coveragepy/issue/183/install-fails-for-python-23
+.. _issue 194: https://bitbucket.org/ned/coveragepy/issue/194/filelocatorrelative_filename-could-mangle
 .. _issue 195: https://bitbucket.org/ned/coveragepy/issue/195/pyo-file-handling-in-codeunit
 .. _tox: http://tox.readthedocs.org/
 

coverage/files.py

@@ -27,7 +27,7 @@ def relative_filename(self, filename):
 
         """
         if filename.startswith(self.relative_dir):
-            filename = filename.replace(self.relative_dir, "")
+            filename = filename.replace(self.relative_dir, "", 1)
         return filename
 
     def canonical_filename(self, filename):

test/test_files.py

@@ -37,6 +37,13 @@ def test_peer_directories(self):
         self.assertEqual(fl.relative_filename(a1), "file1.py")
         self.assertEqual(fl.relative_filename(a2), a2)
 
+    def test_filepath_contains_absolute_prefix_twice(self):
+        # https://bitbucket.org/ned/coveragepy/issue/194/filelocatorrelative_filename-could-mangle
+        fl = FileLocator()
+        d = fl.abs_file(os.curdir)
+        rel = os.path.join('sub', d.lstrip(os.path.sep), 'file1.py')
+        self.assertEqual(fl.relative_filename(fl.abs_file(rel)), rel)
+
 
 class MatcherTest(CoverageTest):
     """Tests of file matchers."""