add tests for validation context

[samuelcolvin]

Turns out I forgot to add these while working on #184

[codecov]

Codecov Report

Merging #220 (a9319b4) into main (5e36e91) will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##             main     #220   +/-   ##
=======================================
  Coverage   98.66%   98.66%           
=======================================
  Files          48       48           
  Lines        5031     5031           
  Branches       35       35           
=======================================
  Hits         4964     4964           
  Misses         67       67           

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