Create test stub that fails when used

[ericcornelissen]

Closes #1307
Relates to #1149

Summary

Expand the set of test stubs with one to simulate that using shescape to escape or quote fails.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 100.00%. Comparing base (a1d451d) to head (8bf7b52).

Additional details and impacted files

@@            Coverage Diff            @@
##              main     #1530   +/-   ##
=========================================
  Coverage   100.00%   100.00%           
=========================================
  Files           17        17           
  Lines         1627      1653   +26     
=========================================
+ Hits          1627      1653   +26     

Flag	Coverage Δ
breakage	85.17% <61.53%> (-0.26%)	⬇️
compatibility	84.81% <61.53%> (-0.38%)	⬇️
e2e-MacOS	91.01% <ø> (ø)
e2e-Ubuntu	91.01% <ø> (ø)
integration-MacOS	99.59% <100.00%> (+<0.01%)	⬆️
integration-Ubuntu	99.59% <100.00%> (+<0.01%)	⬆️
integration-Windows	99.44% <100.00%> (+0.01%)	⬆️
unit	100.00% <ø> (ø)

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Files	Coverage Δ
src/modules/testing.js	100.00% <100.00%> (ø)