service class for making and sending invitations

tests/services/test_invitation.py

@@ -0,0 +1,17 @@
+from tests.factories import UserFactory, WorkspaceFactory
+
+from atst.services.invitation import Invitation
+
+
+def test_invite_member(queue):
+    inviter = UserFactory.create()
+    new_member = UserFactory.create()
+    workspace = WorkspaceFactory.create(owner=inviter)
+    invite_service = Invitation(
+        inviter,
+        workspace,
+        {**new_member.to_dictionary(), "workspace_role": "developer"},
+    )
+    new_invitation = invite_service.invite()
+    assert new_invitation == new_member.invitations[0]
+    assert len(queue.get_queue()) == 1