def gas_injection(ods):
    """
    Adds some FAKE gas injection locations so that the overlay plot will work in tests. It's fine to test
    with dummy data as long as you know it's not real. This function can overwrite existing data if you're not careful.
    The original is modified, so deepcopy first if you want different ODSs.

    :param ods: ODS instance

    :return: ODS instance with FAKE GAS INJECTION HARDWARE INFORMATION added.
    """

    ods['gas_injection.time'] = [0]

    ods['gas_injection.pipe.0.name'] = 'FAKE_GAS_A'
    ods['gas_injection.pipe.0.exit_position.r'] = 2.25
    ods['gas_injection.pipe.0.exit_position.z'] = 0.0
    ods['gas_injection.pipe.0.exit_position.phi'] = 6.5
    ods['gas_injection.pipe.0.valve.0.identifier'] = 'FAKE_GAS_VALVE_A'

    ods['gas_injection.pipe.1.name'] = 'FAKE_GAS_B'
    ods['gas_injection.pipe.1.exit_position.r'] = 1.65
    ods['gas_injection.pipe.1.exit_position.z'] = 1.1
    ods['gas_injection.pipe.1.exit_position.phi'] = 6.5
    ods['gas_injection.pipe.1.valve.0.identifier'] = 'FAKE_GAS_VALVE_B'

    ods['gas_injection.pipe.2.name'] = 'FAKE_GAS_C'
    ods['gas_injection.pipe.2.exit_position.r'] = 2.1
    ods['gas_injection.pipe.2.exit_position.z'] = -0.6
    ods['gas_injection.pipe.2.valve.0.identifier'] = 'FAKE_GAS_VALVE_C'
    # This one deliberately doesn't have a phi angle defined, for testing purposes.

    return ods