add other ways to call decorator

tests/test_core/test_decorator_calls.py

@@ -0,0 +1,39 @@
+import boto
+from boto.exception import EC2ResponseError
+from sure import expect
+
+from moto import mock_ec2
+
+'''
+Test the different ways that the decorator can be used
+'''
+
+
+@mock_ec2
+def test_basic_decorator():
+    conn = boto.connect_ec2('the_key', 'the_secret')
+    list(conn.get_all_instances()).should.equal([])
+
+
+def test_context_manager():
+    conn = boto.connect_ec2('the_key', 'the_secret')
+    conn.get_all_instances.when.called_with().should.throw(EC2ResponseError)
+
+    with mock_ec2():
+        conn = boto.connect_ec2('the_key', 'the_secret')
+        list(conn.get_all_instances()).should.equal([])
+
+    conn.get_all_instances.when.called_with().should.throw(EC2ResponseError)
+
+
+def test_decorator_start_and_stop():
+    conn = boto.connect_ec2('the_key', 'the_secret')
+    conn.get_all_instances.when.called_with().should.throw(EC2ResponseError)
+
+    mock = mock_ec2()
+    mock.start()
+    conn = boto.connect_ec2('the_key', 'the_secret')
+    list(conn.get_all_instances()).should.equal([])
+    mock.stop()
+
+    expect(conn.get_all_instances.when.called_with()).should.throw(EC2ResponseError)