More robust testing

[ladvoc]

More robust testing is needed in the following areas:

• BijectiveDictionary is a generic struct, but tests currently only cover BijectiveDictionary<String, Int>
• Performance testing of common operations: insertion, lookup, iteration, etc.

[DandyLyons]

We should also add benchmark testing.
I just found this package with Apple used to develop Swift Collections
https://swiftpackageindex.com/apple/swift-collections-benchmark

There is also this, which doesn't appear to be officially owned by Apple or the swiftlang organization, but it was announced on the official Swift blog.
https://www.swift.org/blog/benchmarks/

[ladvoc]

I think that's the right solution. Do you want to take this up?

[DandyLyons]

I'll open another Issue, specifically for benchmark testing.