private static FieldUpdate getTensorField(DocumentUpdate update, String fieldName) {
        FieldUpdate fieldUpdate = update.getFieldUpdate(fieldName);
        assertEquals(1, fieldUpdate.size());
        return fieldUpdate;
    }
Tests parsing of various tensor values set at the root, i.e. no 'cells', 'blocks' or 'values'
document/src/test/java/com/yahoo/document/json/JsonReaderTestCase.java