func checkGet(c *gc.C, st *state.State, tag names.MachineTag, expected state.SSHHostKeys) {
keysGot, err := st.GetSSHHostKeys(tag)
c.Assert(err, jc.ErrorIsNil)
c.Check(keysGot, gc.DeepEquals, expected)
}
func checkKeysNotFound(c *gc.C, st *state.State, tag names.MachineTag) {
_, err := st.GetSSHHostKeys(tag)
c.Check(errors.IsNotFound(err), jc.IsTrue)
c.Check(err, gc.ErrorMatches, "keys not found")
}