Add code coverage tooling to the CI

[ethanfrey]

It would be great to see the code coverage on the contract code from the unit tests. To see if critical checks/branches are properly covered.

One popular tool seems to be tarpaulin. But I am open to any other tool as well. (Note tarpaulin has a caveat about signals which is needed for any of the wasm/vm tests, but not when running contracts as native rust).

Deliverable:

• A command to get code coverage for each contract (bonus: also the packages)
• A way to visualize it locally (even if just text)
• Automated upload to a web service in CI (eg. https://coveralls.io or https://codecov.io)

It would nice to run this locally as well. You can look at #171 as a possible way for scripts to work in CI as well as locally.

[ethanfrey]

My quick local trial:

cargo install cargo-tarpaulin
cd cosmwasm-plus/contracts/cw3-flex-multisig

# this print out info on all files in all crates
cargo tarpaulin -v

# this still covers all crates (how to disable workspace?) but also shows html overview
cargo tarpaulin -v --lib -o html
xdg-open tarpaulin-report.html

# this seems to run tests in each crate one after another and get better coverage for all packages
cargo tarpaulin -v --lib --workspace -o html 
xdg-open tarpaulin-report.html

The last one actually gives nice results to help me finish up covering cw4-stake. Most of the missed functions were on my TODO list, but not all. (nb: code coverage of the repo is a bit over 90% - quick nice, but I am happy to try to bump it a bit higher)

[ethanfrey]

After working with the cw4-stake contact a fair bit, I think the following is quite nice (add --workspace to show for all contracts):

cargo tarpaulin --lib --ignore-tests -o html

Or for everything

cargo tarpaulin --lib --ignore-tests --workspace -o html

[maurolacy]

Nice. We can run this as part of the CI, and publish a report somewhere.

[ethanfrey]

@maurolacy this might be an interesting task for Bart if he has experience with any such tooling.

CI stuff, but it does give insight into the project structure