Remove Signonotron2's dependence on flask

The Signonotron2 class doesn't need to depend on flask and it doing so
has the depdency going in the wrong direction.

backdrop/write/admin_ui.py

@@ -17,12 +17,14 @@ def setup(app, db, bucket_repository, user_repository):
     ADMIN_UI_HOST = app.config["BACKDROP_ADMIN_UI_HOST"]
     MAX_UPLOAD_SIZE = 1000000
 
-    app.oauth_service = Signonotron2(
-        client_id=app.config['OAUTH_CLIENT_ID'],
-        client_secret=app.config['OAUTH_CLIENT_SECRET'],
-        base_url=app.config['OAUTH_BASE_URL'],
-        backdrop_admin_ui_host=ADMIN_UI_HOST
-    )
+    @app.before_first_request
+    def setup_oauth_redirect_uri():
+        app.oauth_service = Signonotron2(
+            client_id=app.config['OAUTH_CLIENT_ID'],
+            client_secret=app.config['OAUTH_CLIENT_SECRET'],
+            base_url=app.config['OAUTH_BASE_URL'],
+            redirect_url=url_for(ADMIN_UI_HOST, "oauth_authorized")
+        )
 
     @app.after_request
     def prevent_clickjacking(response):
@@ -63,7 +65,7 @@ def oauth_sign_in():
         This returns a redirect to the OAuth provider, so we shouldn't
         allow this response to be cached.
         """
-        return app.oauth_service.authorize()
+        return redirect(app.oauth_service.authorize())
 
     @app.route(USER_SCOPE + "/sign_out")
     @cache_control.set("private, must-revalidate")

backdrop/write/signonotron2.py

@@ -1,14 +1,13 @@
 from logging import getLogger
-from flask import redirect, json
-from admin_ui_helper import url_for
+import json
 from rauth import OAuth2Service, service
 
 log = getLogger(__name__)
 
 
 class Signonotron2(object):
     def __init__(self, client_id, client_secret, base_url,
-                 backdrop_admin_ui_host):
+                 redirect_url):
         self.signon = OAuth2Service(
             client_id=client_id,
             client_secret=client_secret,
@@ -17,25 +16,23 @@ def __init__(self, client_id, client_secret, base_url,
             access_token_url="%s/oauth/token" % base_url,
             base_url=base_url
         )
-        self.backdrop_admin_ui_host = backdrop_admin_ui_host
-
-    def __redirect_uri(self):
-        return url_for(self.backdrop_admin_ui_host, "oauth_authorized")
+        self.redirect_url = redirect_url
 
     def __json_access_token(self, something):
+        # TODO: use python json package
         return json.loads(something)
 
     def authorize(self):
         params = {
             "response_type": "code",
-            "redirect_uri": self.__redirect_uri()
+            "redirect_uri": self.redirect_url
         }
-        return redirect(self.signon.get_authorize_url(**params))
+        return self.signon.get_authorize_url(**params)
 
     def exchange(self, code):
         data = dict(
             grant_type='authorization_code',
-            redirect_uri=self.__redirect_uri(),
+            redirect_uri=self.redirect_url,
             code=code
         )
         response = self.signon.get_raw_access_token('POST', data=data)

tests/write/test_file_upload_integration.py

@@ -137,7 +137,6 @@ def test_upload_auto_generate_ids(self):
         assert_that(response, has_status(200))
         db = MongoClient('localhost', 27017).backdrop_test
         results = list(db.bucket_with_timestamp_auto_id.find())
-        print(results[0])
 
         assert_that(len(results), is_(18))
         assert_that(results[0], has_entries({

tests/write/test_signonotron2.py

@@ -16,14 +16,14 @@ def setUp(self):
     def tearDown(self):
         self.ctx.pop()
 
-    def test_authorize_returns_a_redirect_to_signon_service(self):
+    def test_authorize_returns_a_url_to_signon_service(self):
         oauth_service = Signonotron2(None, None, None, "")
         oauth_service.signon = Mock()
-        oauth_service.signon.get_authorize_url.return_value = ""
+        oauth_service.signon.get_authorize_url.return_value = "http://example.com"
 
-        response = oauth_service.authorize()
+        url = oauth_service.authorize()
 
-        assert_that(response, has_status(302))
+        assert_that(url, equal_to("http://example.com"))
 
     def test_exchange_returns_none_when_code_is_none(self):
         oauth_service = Signonotron2(None, None, None, "")