async def METHOD_NAME():
    """get_token should raise CredentialUnavailableError for incomplete configuration."""
    with mock.patch.dict(ENVIRON, {}, clear=True):
        with pytest.raises(CredentialUnavailableError) as ex:
            await EnvironmentCredential().get_token("scope")
    for a, b in itertools.combinations(ALL_VARIABLES, 2):  # all credentials require at least 3 variables set
        with mock.patch.dict(ENVIRON, {a: "a", b: "b"}, clear=True):
            with pytest.raises(CredentialUnavailableError) as ex:
                await EnvironmentCredential().get_token("scope")