diff --git a/blenderpack.py b/blenderpack.py
index 6d8096e..f70332c 100755
--- a/blenderpack.py
+++ b/blenderpack.py
@@ -21,7 +21,37 @@ SCHEMA_VERSION = 1
 class BadAddon(Exception):
     pass
 
-def fetch(url, pipe):
+
+# TODO add repolist class
+
+def load_repo(url):
+    """
+    Searches local repo.json for repository with a matching 'url' and returns it
+    """
+    pass #TODO
+
+def write_repo(repo):
+    """
+    Writes repo to local repolist json
+    """
+    pass #TODO
+
+def fetch_repo(url: str) -> dict:
+    """ Requests repo.json from URL and embeds etag/last-modification headers"""
+    local_copy = load_repo(url)
+    headers = {}
+    if 'etag' in local_copy: headers['If-None-Match'] = local_copy['etag']
+    if 'last-modified' in local_copy: headers['If-Modified-Since'] = local_copy['last-modified']
+
+    resp = requests.get(url, headers=headers)
+
+    repo = json.loads(resp.json())
+    repo['etag'] = resp.headers.get('etag')
+    repo['last-modified'] = resp.headers.get('last-modified')
+
+    write_repo(repo)
+
+def refresh(url):
     # we have to explicitly close the end of the pipe we are NOT using,
     # otherwise no exception will be generated when the other process closes its end.
     pipe[0].close()
@@ -30,18 +60,8 @@ def fetch(url, pipe):
     local_repo_path.mkdir(exist_ok=True)
 
     try:
-        # TODO: do conditional request
-        re = requests.get(url)
-
+        fetch_repojson(url)
         pipe[1].send(re.status_code)
-
-        repo = re.json()
-        repo['etag'] = re.headers.get('etag')
-        repo['last-modified'] = re.headers.get('last-modified')
-
-        # just stick it here for now..
-        dump_repo(local_repo_path, repo)
-
     finally:
         pipe[1].close()
 
diff --git a/tests/test_refresh_repos.py b/tests/test_refresh_repos.py
new file mode 100644
index 0000000..98dd42f
--- /dev/null
+++ b/tests/test_refresh_repos.py
@@ -0,0 +1,72 @@
+import requests
+import unittest
+from unittest import mock
+from blenderpack import fetch_repo, load_repo, write_repo
+from datetime import datetime
+import json
+
+# based on https://stackoverflow.com/a/28507806/2730823
+
+# This method will be used by the mock to replace requests.get
+def mocked_requests_get(*args, **kwargs):
+    cidict = requests.structures.CaseInsensitiveDict
+    req_headers = cidict(kwargs.get('headers'))
+    t_fmt = '%a, %m %b %Y %X %Z'
+
+    class MockResponse:
+        def __init__(self, headers: cidict, status_code: int):
+            self.headers = headers
+            self.status_code = status_code
+
+        def json(self):
+            return json.dumps({'url': 'http://someurl.tld/repo.json'})
+
+    if args[0] == 'http://someurl.tld/repo.json':
+        resp_headers = cidict({
+            "ETag": '"2a0094b-b74-55326ced274f3"',
+            "Last-Modified": 'Sun, 13 Mar 2011 13:38:53 GMT',
+        })
+
+        if req_headers == {}:
+            resp_code = 200
+        else:
+            req_headers = cidict(req_headers)
+            resp_code = 304 if req_headers.get('if-none-match', '') == resp_headers['etag']\
+                        or datetime.strptime(req_headers.get('if-modified-since', ''), t_fmt) < \
+                           datetime.strptime(resp_headers['last-modified'], t_fmt) \
+                        else 200
+        return MockResponse(resp_headers, resp_code)
+
+    return MockResponse(None, 404)
+
+_mocked_repo_storage = {}
+def mocked_load_repo(*args, **kwargs):
+    global _mocked_repo_storage
+    if args[0] not in _mocked_repo_storage:
+        _mocked_repo_storage[args[0]] = {'url': args[0]}
+
+    return _mocked_repo_storage[args[0]]
+
+def mocked_write_repo(*args, **kwargs):
+    global _mocked_repo_storage
+    _mocked_repo_storage[args[0]['url']] = args[0]
+
+
+class fetch_url_twice(unittest.TestCase):
+
+    @mock.patch('requests.get', side_effect=mocked_requests_get)
+    @mock.patch('blenderpack.load_repo', side_effect=mocked_load_repo)
+    @mock.patch('blenderpack.write_repo', side_effect=mocked_write_repo)
+    def test_fetch(self, mock_write, mock_load, mock_get):
+        fetch_repo('http://someurl.tld/repo.json')
+        mock_get.assert_called_with('http://someurl.tld/repo.json', headers={})
+
+        fetch_repo('http://someurl.tld/repo.json')
+        mock_get.assert_called_with('http://someurl.tld/repo.json', headers={
+            'If-None-Match': '"2a0094b-b74-55326ced274f3"',
+            'If-Modified-Since': 'Sun, 13 Mar 2011 13:38:53 GMT'
+            })
+
+
+if __name__ == '__main__':
+    unittest.main()