improve sub case text references

[Trass3r]

Extracted from #321 (comment):

The message could be improved:

DEEPEST SUBCASE STACK REACHED (DIFFERENT FROM THE CURRENT ONE):

  "3"

I have no clue what the "CURRENT ONE" is and how it's different. Looks like implementation details to me.
Should be something simple like

TEST CASE:  non-literal type ("3")

Nested cases could be printed like ("3" / "4" / ...) I guess.

[onqtam]

The idea behind the "current" is that we might have popped a subcase or two compared to the deepest stack we might have encountered in the current entrance of this test case. Example:

TEST_CASE("lots of nested subcases") {
    SUBCASE("1") {
        SUBCASE("2") {}
        CHECK(false);
    }
}

when we hit the assert the deepest stack is 1/2 but the current stack is just 1, so the output is this:

TEST CASE:  lots of nested subcases
  1

DEEPEST SUBCASE STACK REACHED (DIFFERENT FROM THE CURRENT ONE):
  1
  2

a.cpp:7: ERROR: CHECK( false ) is NOT correct!
  values: CHECK( false )

and both the current and the deepest subcase stacks are printed, but I guess the current output is confusing.

One other consideration behind the separate rows for each subcase is BDD-style test cases - they are effectively subcases but with a prefix (either Given: or When: or... you get the point), and for them it also makes sense to use separate rows.

Also if the names of subcases are too long then printing everything on a single line will not be readable/optimal either.

However, I agree with you that the current output is weird/confusing/ugly and for short subcase names I would totally prefer your proposal. Perhaps the order of the current/deepest should be switched (so that the deepest is printed first and the current is printed after that - closer to the actual error). Perhaps we could make a new dedicated macro for BDD-style subcases which has an additional flag to distinguish it from the normal ones, so that they are printed differently...

[Trass3r]

Ah ok I used that pattern in value-parameterized tests.
The subcase has technically gone out of scope but since it assigned something to a variable we need that deepest stack.
Maybe one could combine the two lists since they should have the same prefix, just displaying the "tail" differently, e.g. colored if we are in a terminal. Or display them as a tree.

[onqtam]

Displaying as a tree seems like the right way to go indeed, and we could display the deepest nodes of the tree after a row saying deeper subcases reached before the current error: as you suggested. I think it's fine to break/improve the output of subcases & BDD-style test cases.