Add coveralls badge to README

[cljoly]

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[coveralls]

coverage: 88.589%. remained the same
when pulling 8069481 on add-coveralls-badge
into f3c45cd on master.

[cljoly]

I’m a bit disappointed by the whole coverage thing: it does not include doc-tests (would need the nightly compiler and it’s unstable taiki-e/cargo-llvm-cov#2) nor the integration tests (because they are in a separate binary I suspect).

In its current state, it’s a bit misleading. I’m thinking of showing coverage only for the code that’s not behind features and to move back the integration tests that don’t need features in the standard directory.

[cljoly]

cc @czocher

[czocher]

It does not run the doctests, but from what I see it does run the integration tests:

Running tests/integration_test.rs (target/llvm-cov-target/debug/deps/integration_test-98686e68c83a8c03)

running 1 test

We can use the nigthly unstable feature for the doctest support since it does not influence the project, just the CI, which we do not guarantee anything about. What do you think @cljoly?

[cljoly]

You are right I looked too quickly, integration tests are run indeed. And we can give a try to the nightly CI builds, if it turn out to be too unstable (i.e. if it fails on valid code too often), we can always go back to stable.

[cljoly]

Hum, so with nightly / the doctest option, coveralls does not get the sources: https://coveralls.io/builds/57998356/source?filename=rusqlite_migration%2Fsrc%2Fasynch.rs.

That’s annoying. I guess if I have to chose, I prefer to have a slightly lower coverage but an easy access to uncovered lines for contributors who may not want to go through all the trouble of installing cargo-llvm-cov and running it locally.

[cljoly]

Maybe codecov.io would work better on this, but they seem very confused by the fact that I renamed this repo years ago.

[cljoly]

Yeah, the online report on coverage for each file line comes back once I removed the doc-test/nightly stuff.

[czocher]

@cljoly what's the story with tarpaulin and doctests? I noticed the issue they created for them seems solved: xd009642/tarpaulin#13

If it supports them we can migrate easily.

[cljoly]

Yes, that’s a good point, perhaps it won’t be too slow and it’ll work better with the doc-tests. Could you please try to migrate to tarpaulin, if you have time?

[czocher]

@cljoly sure, I'll implement it later today.

[cljoly]

Great thank you.

[czocher]

@cljoly see #57.