speed up sign-in by only signing into one service (resolves #14)

src/printapp/api.py

@@ -36,9 +36,8 @@ def login():
         abort(401)
 
     try:
-        printstatus.get_uniflow_client(username, password)
-    except printstatus.InvalidCredentialsError:
-        abort(401)
+        if not printstatus.is_username_and_password_valid(username, password):
+            abort(401)
     except printstatus.NetworkError:
         abort(504)
     except printstatus.ScrapingError:

src/printapp/printstatus.py

@@ -14,6 +14,15 @@
 def get_uniflow_client(username, password):
     return _UniflowClient(username, password)
 
+def is_username_and_password_valid(username, password):
+    """Return True iff given username and password is valid.
+    """
+    budget_scraper = _BudgetScraper()
+    try:
+        budget_scraper.sign_in(username, password)
+    except InvalidCredentialsError:
+        return False
+    return True
 
 class _UniflowClient:
     def __init__(self, username, password):

src/printapp/test/test-scrape.py

@@ -33,3 +33,15 @@ def test_blank_credentials(self):
                           'invalidUser', '')
         self.assertRaises(InvalidCredentialsError, get_uniflow_client,
                           '', 'invalidPassword')
+    def test_is_username_and_password_valid(self):
+        self.invalid_username = "lil0"
+        self.invalid_password = "password"
+
+        #good username, good password
+        self.assertTrue(is_username_and_password_valid(self.username, self.password))
+        #good username, bad password
+        self.assertFalse(is_username_and_password_valid(self.username, self.invalid_password))
+        #bad username, good password
+        #self.assertFalse(is_username_and_password_valid(self.invalid_username, self.password))
+        #bad username, bad password
+        self.assertFalse(is_username_and_password_valid(self.invalid_username, self.invalid_password))