add default vaule setting that will not override existing env variables

Author: lbudman

pytest_env/plugin.py

@@ -13,4 +13,15 @@ def pytest_load_initial_conftests(args, early_config, parser):
         part = e.partition("=")
         key = part[0].strip()
         value = part[2].strip()
-        os.environ[key] = value
+
+        # use D: as a way to designate a default value 
+        # that will only override env variables if they 
+        # do not exist already
+        dkey = key.split("D:")
+        default_val = False
+        if len(dkey) == 2:
+            key = dkey[1]
+            default_val = True
+
+        if not default_val or key not in os.environ:
+            os.environ[key] = value

setup.py

@@ -6,7 +6,7 @@
     name='pytest-env',
     description=description,
     long_description=description,
-    version='0.5.1',
+    version='0.6.0',
     author='[email protected]',
     author_email='[email protected]',
     url='https://github.com/MobileDynasty/pytest-env',
@@ -24,4 +24,4 @@
         'Programming Language :: Python :: 3',
         'Programming Language :: Python :: 3.3',
     ]
-)
+)