def METHOD_NAME():
    form = CSVValidationMixin()
    # wrap CSV up in SimpleUploadedFile to mirror how a Django view would
    # handle it
    csv_data = "id,description\n0301012A0AA,Adrenaline (Asthma)"
    upload_file = csv_builder(csv_data)
    uploaded_file = SimpleUploadedFile("our csv", upload_file.read())
    form.cleaned_data = {"csv_data": uploaded_file, "coding_system_id": "bnf"}
    with pytest.raises(ValidationError) as e:
        form.clean_csv_data()
    assert len(e.value.messages) == 1
    assert (
        e.value.messages[0]
        == "Expected code header not found: 'dmd_id' or 'code' required"
    )