To give you an anecdote of how unimaginable bugs can be:
I once visited a workshop for some commercial software. At some point of the workshop, we (participants) should executed something we created with that software. It worked for everyone except for me. We looked at it, but even copy-pasting the working project and code from someone else did not help. What was the issue?
At some point, that software created an XML file with some XML comments, which look like this:
<!-- bla bla -->
(Don’t worry, you don’t have to know XML to get my point.)
As it turned out, the name of the user’s Windows account was written into one of the comments, like so:
<!-- bla bla John-->
But what if your username is “-” (dash), as it is on my PC? Then the comment looks like this:
<!-- bla bla --->
The problem is, an XML comment must not end on “--->”, because it’s syntactically incorrect. So when this (syntactically incorrect) XML file was loaded and evaluated at some point, the process failed, resulting in that error I had.
Just to give you an example why many bugs might never be found, just because nobody would ever have thought of them.
