Fix OverrideValidatorTest

[justin-tay]

Closes #1158

Fixes the test that wasn't setting format assertions to be enabled.

[codecov-commenter]

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Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 78.15%. Comparing base (48ca3c2) to head (153c097).
Report is 83 commits behind head on master.

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Additional details and impacted files

@@             Coverage Diff              @@
##             master    #1159      +/-   ##
============================================
- Coverage     78.90%   78.15%   -0.76%     
- Complexity     1965     2067     +102     
============================================
  Files           172      201      +29     
  Lines          6352     6861     +509     
  Branches       1255     1255              
============================================
+ Hits           5012     5362     +350     
- Misses          867     1032     +165     
+ Partials        473      467       -6     

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