Add codecov config file, excluded glacier & dao forks, add codecov badge to README

[Carsons-Eels]

What was wrong?

Code coverage unfairly included glacier forks and the dao fork, for which we will not create tests

Closes issues #1139 and #1141

How was it fixed?

Excluded glacier forks in config file

Cute Animal Picture

[codecov-commenter]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 83.86%. Comparing base (2926c00) to head (b25747b).

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #1168      +/-   ##
==========================================
- Coverage   84.87%   83.86%   -1.02%     
==========================================
  Files         649      649              
  Lines       36122    36122              
  Branches        0     3224    +3224     
==========================================
- Hits        30659    30293     -366     
  Misses       5463     5463              
- Partials        0      366     +366     

Flag	Coverage Δ
unittests	83.86% <ø> (-1.02%)	⬇️

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[SamWilsn]

I realize this is still a draft and that you're probably aware, but just in case you haven't seen it yet, arrow_glacier is still included:

[SamWilsn]

I hope you don't mind, but I took a quick look at pytest-cov's documentation, and it looks like we can exclude directories earlier in the process. We could maybe add a section like this to pyproject.toml (and add the --cov-config=pyproject.toml option in tox.ini).

[tool.coverage.run]
omit = [
    "src/ethereum/*_glacier/*",
    "src/ethereum/dao_fork/*",
]

[Carsons-Eels]

I hope you don't mind, but I took a quick look at pytest-cov's documentation, and it looks like we can exclude directories earlier in the process. We could maybe add a section like this to pyproject.toml (and add the --cov-config=pyproject.toml option in tox.ini).

[tool.coverage.run]
omit = [
    "src/ethereum/*_glacier/*",
    "src/ethereum/dao_fork/*",
]

Not at all, this is good! I'll update the PR

[SamWilsn]

Looks like codecov is still counting the glacier forks...

I wonder if it has something to do with how tox is passing the path? In the console output, we have lines like:

.tox/py3/lib/python3.10/site-packages/ethereum/dao_fork/__init__.py

Perhaps the glob we need to use is */ethereum/dao_fork/*?

[SamWilsn]

For future PRs, prefer rebase over merge commits please!