With more error handling, we're up to 13% (minus [clock]) of tcl's test suite.
I spoke on the tcl-core list about a test that I was passing that I hadn't written the builtin for yet - they had split up the error code checking, and the error message handling. Well, having no command generates the same error code as the bad arguments error code. They seem to be aware of the issue, and most of the tests are written in such a way to check both simultaneously, which avoids the false positive.
They did point out that lots of the new tests are in a different format than the old tests; this is probably reducing our pass rate. Yet another reason to move on being able to use tcltest directly; but tcltest uses a lot of the language itself, so it won't be simple.