func (*macaroonSuite) TestJSONRoundTrip(c *gc.C) {
	// jsonData produced from the second example in libmacaroons
	// example README, but with the signature tweaked to
	// match our current behaviour.
	// TODO fix that behaviour so that our signatures match.
	jsonData := `{"caveats":[{"cid":"account = 3735928559"},{"cid":"this was how we remind auth of key\/pred","vid":"AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA027FAuBYhtHwJ58FX6UlVNFtFsGxQHS7uD\/w\/dedwv4Jjw7UorCREw5rXbRqIKhr","cl":"http:\/\/auth.mybank\/"}],"location":"http:\/\/mybank\/","identifier":"we used our other secret key","signature":"6e315b0b391e8c6cc6f8d88fc22933a13430fb289b2fb613cf70f746bbe7d27d"}`

	var m macaroon.Macaroon
	err := json.Unmarshal([]byte(jsonData), &m)
	c.Assert(err, gc.IsNil)
	c.Assert(hex.EncodeToString(m.Signature()), gc.Equals,
		"6e315b0b391e8c6cc6f8d88fc22933a13430fb289b2fb613cf70f746bbe7d27d")
	data, err := m.MarshalJSON()
	c.Assert(err, gc.IsNil)

	// Check that the round-tripped data is the same as the original
	// data when unmarshalled into an interface{}.
	var got interface{}
	err = json.Unmarshal(data, &got)
	c.Assert(err, gc.IsNil)

	var original interface{}
	err = json.Unmarshal([]byte(jsonData), &original)
	c.Assert(err, gc.IsNil)

	c.Assert(got, gc.DeepEquals, original)
}
func assertEqualMacaroons(c *gc.C, m0, m1 *macaroon.Macaroon) {
	m0json, err := m0.MarshalJSON()
	c.Assert(err, gc.IsNil)
	m1json, err := m1.MarshalJSON()
	var m0val, m1val interface{}
	err = json.Unmarshal(m0json, &m0val)
	c.Assert(err, gc.IsNil)
	err = json.Unmarshal(m1json, &m1val)
	c.Assert(err, gc.IsNil)
	c.Assert(m0val, gc.DeepEquals, m1val)
}