said by Mele20:File detection is probably the most important function of an AV.
Yes, but the test in not about file detection but about scanning detection. Detection of a file by an AV is achieved with different technics. From the standard comparison with signature to running into a sandbox environment or heuristics or behaviour analysis.
By only scanning and not executing the file the test assess the performance of only some features of AVs (typically signature or heuristics detection). Some detection technics also needs to analyse the threat over a time period or needs the threat been actually downloaded from an actual web site(real life scenario). This is not actually implemented in thi specific test.
You need to put these tests results into context, something many users are indeed not able to do. This is why the best test environment is you and your daily work with the PC.