Let create a test that focuses on dotted paths and array traversal. For example, given a predicate with a dotted path like {'a.b.c': {$eq: 2}}, there is a wide variety of input data that is interesting to test:

• 'a' might be missing, or a scalar
• 'a' might be an object, in which:
  • 'b' might be missing, scalar, object, array ...
• 'a' might be an array, in which the elements are:
  • scalars, objects, arrays ...

The path 'a.b.c' can pick out zero, one, or many values depending on where the arrays / scalars / missing fields are. So another thing we can vary is: how many leaves match the {$eq: 2} predicate? zero, one or many.