Unit tests for misc lib/utils/ files

[lambda7xx]

Description of changes:
add test for repo-refactor utils test

Before merging:

• add test for bidict, stack_map, stack_string, stack_vector, disjoint_set
• add test for dot_file, record_formatter
• add test for containers
  • join_strings
  • find
  • sum
  • sum with condition
  • product
  • product_where
  • contains
  • contains_key
  • map_keys
  • filter_keys
  • map_values
  • keys
  • values
  • unique
  • item
  • index_of
  • intersection
  • are_disjoint
  • restrict_keys
  • merge_maps
  • merge_maps(bidict)
  • lookup_in
  • lookup_in_l
  • lookup_in_r
  • set_union
  • is_subseteq_of
  • is_superseteq_of
  • map_over_unordered_set
  • get_only
  • get_first
  • extend
  • all_of
  • count
  • are_all_same
  • vector_transform
  • as_vector
  • transform_vector
  • transform
  • maximum
  • enumerate
  • reversed
  • sorted_by
  • value_all
  • subvec
  • extend
  • flatmap
• add test for others

---

This change is 

[lambda7xx]

lib/utils/test/src/test_variant.cc line 21 at r1 (raw file):

Previously, lockshaw (Colin Unger) wrote…

Cast doesn't function based on conversion of the element types of variant (i.e., float -> double). This test case is a bit unclear as to exactly what the semantics of cast should be

I add comments

[lambda7xx]

lib/utils/test/src/test_stack_string.cc line 17 at r1 (raw file):

Previously, lockshaw (Colin Unger) wrote…

What if the assigned string is shorter than the MAXSIZE or longer than the MAXSIZE?

add test for shorter. it we use longer than the MAXSIZE, the assert fails and throw an error.

[lockshaw]

Moving to #940