def METHOD_NAME(self):
    x0 = self.real_parameters * 1.1
    mcmc = pints.MetropolisRandomWalkMCMC(x0)
    # One round of ask-tell must have been run
    self.assertRaisesRegex(
        RuntimeError, 'already running', mcmc.replace, x0, 1)
    mcmc.ask()
    # One round of ask-tell must have been run
    self.assertRaises(RuntimeError, mcmc.replace, x0, 1)
    mcmc.tell(0.5)
    mcmc.replace([1, 2, 3], 10)
    mcmc.replace([1, 2, 3], 10)
    # New position must have correct size
    self.assertRaisesRegex(
        ValueError, '`current` has the wrong dimensions',
        mcmc.replace, [1, 2], 1)
    # Proposal can be changed too
    mcmc.ask()
    mcmc.replace([1, 2, 3], 10, [3, 4, 5])
    # New proposal must have correct size
    self.assertRaisesRegex(
        ValueError, '`proposed` has the wrong dimensions',
        mcmc.replace, [1, 2, 3], 3, [3, 4])