fix issue354: avoid tmpdir fixture to create too long filenames especially

when parametrization is used

CHANGELOG

@@ -8,6 +8,9 @@ Changes between 2.4.1 and 2.4.2
 - avoid "IOError: Bad Filedescriptor" on pytest shutdown by not closing
   the internal dupped stdout (fix is slightly hand-wavy but work).
 
+- avoid tmpdir fixture to create too long filenames especially
+  when parametrization is used (issue354)
+
 Changes between 2.4.0 and 2.4.1
 -----------------------------------
 

_pytest/tmpdir.py

@@ -64,5 +64,8 @@ def tmpdir(request):
     """
     name = request.node.name
     name = py.std.re.sub("[\W]", "_", name)
+    MAXVAL = 30
+    if len(name) > MAXVAL:
+        name = name[:MAXVAL]
     x = request.config._tmpdirhandler.mktemp(name, numbered=True)
     return x

testing/test_tmpdir.py

@@ -91,3 +91,12 @@ def test_tmpdir_always_is_realpath(testdir):
     result = testdir.runpytest("-s", p, '--basetemp=%s/bt' % linktemp)
     assert not result.ret
 
+def test_tmpdir_too_long_on_parametrization(testdir):
+    testdir.makepyfile("""
+        import pytest
+        @pytest.mark.parametrize("arg", ["1"*1000])
+        def test_some(arg, tmpdir):
+            tmpdir.ensure("hello")
+    """)
+    reprec = testdir.inline_run()
+    reprec.assertoutcome(passed=1)