Set default session cookie name.

tests/features/session.feature

@@ -5,4 +5,4 @@ Feature: Session
 	Scenario: Session ID is set
 		Given a running server
 		When the home page is accessed
-		Then there is a session id
+		Then there is a default session id

tests/step_defs/test_session.py

@@ -19,7 +19,13 @@ def access_home_page(server, page):
     page.request_url(url)
 
 
-@then("there is a session id")
+@then("there is a default session id")
 def confirm_session(page):
     """Confirm session id exists."""
-    assert len(page.get_cookies()), "No cookies received."
+    cookies = page.get_cookies()
+    name = "morethantext.sid"
+    cookie = None
+    for holder in cookies:
+        if holder.name == name:
+            cookie = holder
+    assert cookie, f"Did not find cookie {name}, but retrieved {cookies}"