Add instructions for coverage reporting using Pkg.test

[marekdedic]

Hi,
the current instructions in the readme say that you should run julia --code-coverage=user. While in some cases, this might be applicable, in the case of using Pkg.test(), this will not work - the coverage won't get reported. You need to use something like julia --project -e "using Pkg; Pkg.test(; coverage = true);"

I don't know whether to replace the instructions or just add this somehow. However, this way of turning coverage on is actually preferable - if you are using the Julia 1.2.0 test-only dependencies, the only way to invoke tests (AFAIK) is to use Pkg.test() - using include("test/runtests.jl") will not work.

[marekdedic]

Related to #9

[DilumAluthge]

I think that these instructions are already in the README, right?

For example, if you look at item 2 under https://github.com/JuliaCI/Coverage.jl/blob/master/README.md#tracking-coverage-with-codecovio, it says:

2. Use the command line option when you run your tests:

• Either with something like julia --code-coverage test/runtests.jl, or
• with something like julia -e 'Pkg.test("MyPkg", coverage=true)'

[marekdedic]

Ugh, I missed it down there...

I was talking about the instructions at the top of the readme...

Thanks,
Marek

[DilumAluthge]

@marekdedic Does this seem better? #248

[marekdedic]

Definitely, thanks!