importorskip: Allow non-integer version strings

Use `pkg_resources.parse_version` to parse version strings.
This can handle 'dev', 'rc', alpha and beta version strings,
among others.

CHANGELOG

@@ -1,6 +1,9 @@
 2.7.3 (compared to 2.7.2)
 -----------------------------
 
+- Allow 'dev', 'rc', or other non-integer version strings in `importorskip`.
+  Thanks to Eric Hunsberger for the PR.
+
 - fix issue856: consider --color parameter in all outputs (for example
   --fixtures). Thanks Barney Gale for the report and Bruno Oliveira for the PR.
 

_pytest/runner.py

@@ -3,6 +3,8 @@ import bdb
 import sys
 from time import time
 
+from pkg_resources import parse_version
+
 import py
 import pytest
 from py._code.code import TerminalRepr
@@ -483,8 +485,6 @@ def importorskip(modname, minversion=None):
     """ return imported module if it has at least "minversion" as its
     __version__ attribute.  If no minversion is specified the a skip
     is only triggered if the module can not be imported.
-    Note that version comparison only works with simple version strings
-    like "1.2.3" but not "1.2.3.dev1" or others.
     """
     __tracebackhide__ = True
     compile(modname, '', 'eval') # to catch syntaxerrors
@@ -496,9 +496,7 @@ def importorskip(modname, minversion=None):
     if minversion is None:
         return mod
     verattr = getattr(mod, '__version__', None)
-    def intver(verstring):
-        return [int(x) for x in verstring.split(".")]
-    if verattr is None or intver(verattr) < intver(minversion):
+    if verattr is None or parse_version(verattr) < parse_version(minversion):
         skip("module %r has __version__ %r, required is: %r" %(
              modname, verattr, minversion))
     return mod

testing/test_runner.py

@@ -471,6 +471,19 @@ def test_importorskip_imports_last_module_part():
     ospath = pytest.importorskip("os.path")
     assert os.path == ospath
 
+def test_importorskip_dev_module():
+    try:
+        mod = py.std.types.ModuleType("mockmodule")
+        mod.__version__ = '0.13.0.dev-43290'
+        sys.modules['mockmodule'] = mod
+        mod2 = pytest.importorskip('mockmodule', minversion='0.12.0')
+        assert mod2 == mod
+        pytest.raises(pytest.skip.Exception, """
+            pytest.importorskip('mockmodule1', minversion='0.14.0')""")
+    except pytest.skip.Exception:
+        print(py.code.ExceptionInfo())
+        pytest.fail("spurious skip")
+
 
 def test_pytest_cmdline_main(testdir):
     p = testdir.makepyfile("""