Value-Parameterized Tests - allowed type criteria

[halt9k]

In the docs How to Write Value-Parameterized Tests it says for parameter

T can be any copyable type

for the experiment, I tried to use it with fs:path and got Stack Overflow during print near testing::internal::UniversalPrinter

Standard checks on fs:path and string (is_copy_constructible, is_trivially_copy_constructible, so on) - mostly give same result: either both are, either both are not.

Can you please hint type test function which will distinguish?

Sub-question: aren't test framework supposed to ensure automatically if provided type meets criteria rather than generate SO? For example, to check if class have PrintTo() implemented if this is requirement.