adding more compat functionality

uranium/compat/__init__.py

@@ -20,4 +20,9 @@
 try:
     from importlib import import_module
 except:
-    from c_importlib import import_module
+    from .c_importlib import import_module
+
+try:
+    from subprocess import check_output
+except:
+    from .check_output import check_output

uranium/compat/check_output.py

@@ -0,0 +1,22 @@
+import subprocess
+
+
+def check_output(*popenargs, **kwargs):
+    r"""Run command with arguments and return its output as a byte string.
+
+    Backported from Python 2.7 as it's implemented as pure python on stdlib.
+
+    >>> check_output(['/usr/bin/python', '--version'])
+    Python 2.6.2
+    """
+    process = subprocess.Popen(stdout=subprocess.PIPE, *popenargs, **kwargs)
+    output, unused_err = process.communicate()
+    retcode = process.poll()
+    if retcode:
+        cmd = kwargs.get("args")
+        if cmd is None:
+            cmd = popenargs[0]
+        error = subprocess.CalledProcessError(retcode, cmd)
+        error.output = output
+        raise error
+    return output

uranium/tests/test_full/test_egg_resolution.py

@@ -2,7 +2,7 @@
 tests for the warmup script
 """
 import os
-import subprocess
+from uranium.compat import check_output
 from uranium.tests.utils import FullUraniumBaseTest
 from nose.tools import eq_
 
@@ -25,7 +25,7 @@ def test_egg_resolution(self):
         """
         ensure that egg version take precedence version specs
         """
-        output = subprocess.check_output(['./bin/python', '-c', 'import requests; print(requests.__version__)'],
-                                         cwd=self.root)
+        output = check_output(['./bin/python', '-c', 'import requests; print(requests.__version__)'],
+                              cwd=self.root)
         output = output.decode('ascii').strip()
         eq_(output, '2.3.0')