minor test coverage improvement
minor test coverage improvement

izzyalonso/tndata_backend,tndatacommons/tndata_backend,tndatacommons/tndata_backend,izzyalonso/tndata_backend,tndatacommons/tndata_backend,izzyalonso/tndata_backend,izzyalonso/tndata_backend,tndatacommons/tndata_backend