internal/core/adt: add tests for 3780
This is added post fix as the test caused a panic.
Fixes #3780
Signed-off-by: Marcel van Lohuizen <mpvl@gmail.com>
Change-Id: Ia34135c6444dfb2a7d777c4df93fb7c4a13c0260
Reviewed-on: https://review.gerrithub.io/c/cue-lang/cue/+/1210973
TryBot-Result: CUEcueckoo <cueckoo@cuelang.org>
Reviewed-by: Daniel Martí <mvdan@mvdan.cc>
Unity-Result: CUE porcuepine <cue.porcuepine@gmail.com>