test: add more hook tests

[smyrick]

Add unit test coverage for SchemaGeneratorHooks

[codecov-io]

Codecov Report

Merging #133 into master will increase coverage by 2.68%.
The diff coverage is 100%.

@@             Coverage Diff              @@
##             master     #133      +/-   ##
============================================
+ Coverage     93.07%   95.75%   +2.68%     
  Complexity      154      154              
============================================
  Files            47       50       +3     
  Lines           491      495       +4     
  Branches         96       99       +3     
============================================
+ Hits            457      474      +17     
+ Misses            8        5       -3     
+ Partials         26       16      -10

Impacted Files	Coverage Δ	Complexity Δ
.../com/expedia/graphql/hooks/SchemaGeneratorHooks.kt	100% <100%> (+7.69%)	0 <0> (ø)	⬇️
...pedia/graphql/generator/types/ObjectTypeBuilder.kt	94.73% <0%> (ø)	2% <0%> (ø)	⬇️
...xpedia/graphql/generator/types/QueryTypeBuilder.kt	100% <0%> (ø)	6% <0%> (+1%)	⬆️
...a/graphql/generator/extensions/kClassExtensions.kt	100% <0%> (ø)	0% <0%> (ø)	⬇️
...dia/graphql/generator/types/MutationTypeBuilder.kt	100% <0%> (ø)	6% <0%> (+1%)	⬆️
...phql/generator/extensions/graphQLTypeExtensions.kt
...ia/graphql/exceptions/InvalidQueryTypeException.kt	100% <0%> (ø)	1% <0%> (?)
...xceptions/InvalidSchemaDirectiveWiringException.kt	100% <0%> (ø)	1% <0%> (?)
.../graphql/generator/extensions/graphQLExtensions.kt	100% <0%> (ø)	0% <0%> (?)
...graphql/exceptions/InvalidMutationTypeException.kt	100% <0%> (ø)	1% <0%> (?)
... and 1 more

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[smyrick]

I cannot cover the on failure branch because that is technically unreachable code since we expect an exception to be thrown.

I think a better predicate is this #134