Improve Test coverage above 85%

[itrharrison]

Now that we have coverage reports, we should review where there are untested parts of SOLikeT and implement tests.

I won't set a goal %, but we should make the best efforts we can.

[itrharrison]

The current coverage is 76.00% and has improved by 8% in the past year 🎉 . For v0.1 we should aim for at least (arbitray number) 85%.
https://app.codecov.io/gh/simonsobs/SOLikeT/

[itrharrison]

The coverage report is located here:
https://app.codecov.io/gh/simonsobs/SOLikeT