putting the pieces in place to inject environment variables

setup.py

@@ -19,7 +19,7 @@
 ]
 
 setup(name='uranium',
-      version='0.0.55',
+      version='0.0.56',
       description='a build system for python',
       long_description='a build system for python',
       author='Yusuke Tsutsumi',

uranium/tests/test_virtualenv_manager.py

@@ -0,0 +1,44 @@
+import os
+import tempfile
+from nose.tools import ok_
+from uranium.virtualenv_manager import inject_into_file
+
+
+class TestInjectIntoFile(object):
+
+    def setUp(self):
+        _, self.temp_file = tempfile.mkstemp()
+
+    def tearDown(self):
+        os.unlink(self.temp_file)
+
+    def test_inject_empty_file(self):
+        inject_into_file(self.temp_file, "foo")
+        with open(self.temp_file) as fh:
+            ok_("foo" in fh.read())
+
+    def test_inject_twice(self):
+        """
+        injecting twice should only result
+        in the latest entry in the file.
+        """
+        inject_into_file(self.temp_file, "foo")
+        inject_into_file(self.temp_file, "boo")
+
+        with open(self.temp_file) as fh:
+            content = fh.read()
+
+        ok_("foo" not in content)
+        ok_("boo" in content)
+
+    def test_injection_with_content(self):
+        with open(self.temp_file, 'w+') as fh:
+            fh.write("this is already in here")
+
+        inject_into_file(self.temp_file, "foo")
+
+        with open(self.temp_file) as fh:
+            content = fh.read()
+
+        ok_("this is already in here" in content)
+        ok_("foo" in content)

uranium/virtualenv_manager.py

@@ -1,4 +1,5 @@
 import logging
+import re
 import os
 from virtualenv import create_environment
 
@@ -26,3 +27,35 @@ def is_virtualenv(path):
         if not os.path.exists(target_path):
             return False
     return True
+
+INJECT_WRAPPER = "# URANIUM_INJECT THIS"
+
+INJECT_MATCH = re.compile("(\n?{0}.*{0}\n)".format(INJECT_WRAPPER), re.DOTALL)
+
+INJECT_TEMPLATE = """
+{0}
+{{body}}
+{0}
+""".format(INJECT_WRAPPER)
+
+
+def inject_into_activate_this(venv_root, body):
+    """
+    inject a body into activate_this.py.
+
+    this will overwrite any values previously injected into activate_this.
+    """
+    activate_this_file = os.path.join(venv_root, 'bin', 'activate_this.py')
+    inject_into_file(activate_this_file, body)
+
+
+def inject_into_file(path, body):
+    """ inject into a file """
+    with open(path) as fh:
+        content = fh.read()
+
+    content = INJECT_MATCH.sub("", content)
+    content += INJECT_TEMPLATE.format(body=body)
+
+    with open(path, 'w+') as fh:
+        fh.write(content)