Change isapprox(a,b) to a \approx b in tests

[mikerouleau]

I found a TODO note in /test/nlp.jl indicating this should be done (probably because it's cleaner), so I worked on the low-hanging fruit.

Not related to any open issues (that I'm aware of).

[codecov]

Codecov Report

Merging #2419 (9eacdea) into master (2b0d910) will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##           master    #2419   +/-   ##
=======================================
  Coverage   92.26%   92.26%           
=======================================
  Files          43       43           
  Lines        4614     4614           
=======================================
  Hits         4257     4257           
  Misses        357      357           

---

Continue to review full report at Codecov.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update 2b0d910...9eacdea. Read the comment docs.

[odow]

Thanks @mikerouleau. I'll merge this since you took the effort to make the changes. (It looks like you ran the formatter as well! I'm still in the process of rolling it out.)

If you find other TODOs in the source, and can't find a corresponding issue, please open one so we can discuss what to do.

If you have time, and are interested in contributing to JuMP, you can take a look at the issues marked "Help wanted": https://github.com/jump-dev/JuMP.jl/labels/help%20wanted

Here's a good one to get started with: #2371