Add support for tca95xx i/o extenders.

[schmidtw]

1. 👍
2. n/a
3. 👍

Things of note

• I am able to test the TCA9534 and TCA9535 chips using a RPI4. I included chips that were nearly identical as to reduce the likelihood of introducing a bug.
• I added a conn.Conn interface and implemented that for the extender to allow access to the entire port as a byte.
• This code is based on the mcp23xxx code pretty heavily.

[maruel]

Hi! Thanks for the contribution! It's really appreciated.
Would you mind fixing the staticcheck warning? It helps code readability overall.

[schmidtw]

Can I add https://github.com/stretchr/testify to help me clean up a bunch of cruft in the unit tests?

[maruel]

While I understand the value for those who are familiar with this kind of library, a package like https://pkg.go.dev/github.com/stretchr/testify/assert is not what I call a great design. It's so large that it cannot fit in my head, which means that I have to look up every single function when I use it, or try to guess what it does based on the name. Feel free to create a one-off local function in the test file to reduce copy pasting.

[codecov-commenter]

⚠️ Please install the to ensure uploads and comments are reliably processed by Codecov.

Codecov Report

Attention: Patch coverage is 70.33898% with 70 lines in your changes missing coverage. Please review.

Project coverage is 64.7%. Comparing base (600c8cc) to head (4c598f2).
Report is 23 commits behind head on main.

Files with missing lines	Patch %	Lines
tca95xx/pins.go	60.4%	36 Missing and 4 partials ⚠️
tca95xx/tca95xx.go	78.2%	8 Missing and 4 partials ⚠️
tca95xx/variants.go	63.6%	11 Missing and 1 partial ⚠️
tca95xx/registers.go	87.2%	4 Missing and 2 partials ⚠️

Additional details and impacted files

@@           Coverage Diff           @@
##            main     #51     +/-   ##
=======================================
+ Coverage   64.4%   64.7%   +0.3%     
=======================================
  Files         56      60      +4     
  Lines       6824    7060    +236     
=======================================
+ Hits        4397    4570    +173     
- Misses      2283    2337     +54     
- Partials     144     153      +9     

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[schmidtw]

Is there anything else I need to do before you can merge?

[maruel]

Thanks a lot for the PR. Apologies for the delay, work was busy this week.