## Summary Python's module resolver is case sensitive. This PR adds mdtests that assert that our module resolution is case sensitive. The tests currently all pass because our in memory file system is case sensitive. I'll add support for using the real file system to the mdtest framework in a separate PR. This PR also adds support for specifying extra search paths to the mdtest framework. ## Test Plan The tests fail when running them using the real file system.
Markdown files within the mdtest/ subdirectory are tests of type inference and type checking;
executed by the tests/mdtest.rs integration test.
See crates/red_knot_test/README.md for documentation of this test format.