Added test case to join gang (#123)

tests/test_join_gang.py

@@ -0,0 +1,24 @@
+from tests.mocks.mock_gang_repository import MockGangRepository
+from tests.mocks.mock_outlaw_repository import MockOutlawRepository
+from thesheriff.application.gang.request.join_gang_request \
+    import JoinGangRequest
+from thesheriff.application.outlaw.join_gang import JoinGang
+from thesheriff.domain.gang.gang import Gang
+from thesheriff.domain.outlaw.outlaw import Outlaw
+
+
+def test_join_gangs():
+    gang_repository = MockGangRepository()
+    outlaw_repository = MockOutlawRepository()
+
+    previous_gang = Gang(1, "APreviousGang")
+    gang_i_want_to_join = Gang(2, "TheWorstGang")
+    gang_repository.add(gang_i_want_to_join)
+    outlaw = Outlaw("VeryBadGuy", "iamabadguy@yopmail.com", 1)
+    outlaw.gangs = [previous_gang]
+    outlaw_repository.add(outlaw)
+
+    request = JoinGangRequest(gang_i_want_to_join.id, outlaw.id)
+    JoinGang(outlaw_repository, gang_repository).execute(request)
+
+    assert len(outlaw.gangs) == 2