Reorganize SWF tests so they're shorter and easier to use

tests/test_swf/models/test_activity_task.py

@@ -0,0 +1,26 @@
+from sure import expect
+
+from moto.swf.models import ActivityTask
+
+from ..utils import make_workflow_execution
+
+
+def test_activity_task_creation():
+    wfe = make_workflow_execution()
+    task = ActivityTask(
+        activity_id="my-activity-123",
+        activity_type="foo",
+        input="optional",
+        workflow_execution=wfe,
+    )
+    task.workflow_execution.should.equal(wfe)
+    task.state.should.equal("SCHEDULED")
+    task.task_token.should_not.be.empty
+    task.started_event_id.should.be.none
+
+    task.start(123)
+    task.state.should.equal("STARTED")
+    task.started_event_id.should.equal(123)
+
+    task.complete()
+    task.state.should.equal("COMPLETED")