[Feature Request] assert_raises should report calling location

[keith]

Review Mojo's priorities

• I have read the roadmap and priorities and I believe this request falls within the priorities.

What is your request?

It would be useful if the error message produced when assert_raises fails, and therefore it raises itself

mojo/stdlib/src/testing/testing.mojo

Line 386 in f5f5109

raise Error("AssertionError: Didn't raise")

included the location of the caller who didn't raise.

What is your motivation for this change?

Currently if you have a single test file with multiple assert_raises conditions, like this file:

mojo/stdlib/test/collections/test_list.mojo

Lines 404 to 414 in f5f5109

	with assert_raises(contains="ValueError: Given element is not in list"):
	__type_of(test_list_a).index(test_list_a, 50, start=-5, end=-1)
	with assert_raises(contains="ValueError: Given element is not in list"):
	__type_of(test_list_a).index(test_list_a, 50, start=0, end=-1)
	with assert_raises(contains="ValueError: Given element is not in list"):
	__type_of(test_list_a).index(test_list_a, 10, start=-4, end=-1)
	with assert_raises(
	contains=(
	"Given 'start' parameter (5) is out of range. List only has 5"
	" elements."
	)

If one of the conditions fails, the error message is just:

Unhandled exception caught during execution: AssertionError: Didn't raise

with no indication of where the assertion is coming from

Any other details?

No response