Basic things I would expect would include:
EXCEL:
Applying a filter to a column.
Sorting the contents of a spreadsheet on a filter.
Sorting on more than one condition.
Creating a simple formula, such as calculating VAT or something.
Using things like SUMIF/SUMIFS, COUNTA, COUNTIF/COUNTIFs etc to select subsets of data.
Pivot Tables, if you already use them.
WORD:
Formatting;
Spellcheck;
Knowing how to input those tricky characters you have to hunt for, like " e acute" in French;
Spacing of lines inside paragraphs and between paragraphs;
Knowing how to ensure 2 pieces of text stay together and don't end up on two different pages (the answer is NOT to insert a page break);
Applying 'styles' to titles and using them to help structure a document;
Creating a Table of contents, or an Index, to a document (once you've mastered styles).
Check the job specification: if there are any features and functions mentioned, there's your answer. (It's surprising how many people don't do this!)
I once gave such a test. To start with, the applicant had to decide whether to use Excel or Word this was actually important . One woman who claimed she used all sorts of functions in Excel, had never created a spreadsheet from scratch, and actually didn't know how to create a new file in Excel. (She didn't get the job, in case you are wondering!)