tests: extract run_python() utility function

Proposal is to use it for new subprocess tests where module is commited to repo

tests/__init__.py

@@ -6,6 +6,8 @@ try:
 except ImportError:
     resource = None
 import signal
+import subprocess
+import sys
 import unittest
 import warnings
 
@@ -290,5 +292,24 @@ def get_database_auth():
             pass
     return retval
 
+
+def run_python(path):
+    if not path.endswith('.py'):
+        path += '.py'
+    path = os.path.abspath(path)
+    dir_ = os.path.dirname(path)
+    new_env = os.environ.copy()
+    new_env['PYTHONPATH'] = os.pathsep.join(sys.path + [dir_])
+    p = subprocess.Popen(
+        [sys.executable, path],
+        env=new_env,
+        stderr=subprocess.STDOUT,
+        stdin=subprocess.PIPE,
+        stdout=subprocess.PIPE,
+    )
+    output, _ = p.communicate()
+    return output
+
+
 certificate_file = os.path.join(os.path.dirname(__file__), 'test_server.crt')
 private_key_file = os.path.join(os.path.dirname(__file__), 'test_server.key')

tests/patcher_test.py

@@ -4,7 +4,7 @@ import subprocess
 import sys
 import tempfile
 
-from tests import LimitedTestCase, main, skip_with_pyevent
+from tests import LimitedTestCase, main, run_python, skip_with_pyevent
 
 
 base_module_contents = """
@@ -43,21 +43,16 @@ class ProcessBase(LimitedTestCase):
         shutil.rmtree(self.tempdir)
 
     def write_to_tempfile(self, name, contents):
-        filename = os.path.join(self.tempdir, name + '.py')
-        fd = open(filename, "w")
+        filename = os.path.join(self.tempdir, name)
+        if not filename.endswith('.py'):
+            filename = filename + '.py'
+        fd = open(filename, "wb")
         fd.write(contents)
         fd.close()
 
     def launch_subprocess(self, filename):
-        python_path = os.pathsep.join(sys.path + [self.tempdir])
-        new_env = os.environ.copy()
-        new_env['PYTHONPATH'] = python_path
-        if not filename.endswith('.py'):
-            filename = filename + '.py'
-        p = subprocess.Popen(
-            [sys.executable, os.path.join(self.tempdir, filename)],
-            stdout=subprocess.PIPE, stderr=subprocess.STDOUT, env=new_env)
-        output, _ = p.communicate()
+        path = os.path.join(self.tempdir, filename)
+        output = run_python(path)
         lines = output.split("\n")
         return output, lines