UndefinedFunctionError after updating hackney and excoveralls the to latest version

[AndrewDryga]

$ mix coveralls.travis --exclude pending
Excluding tags: [:pending]
....
Finished in 0.2 seconds
4 tests, 0 failures
Randomized with seed 797741
** (UndefinedFunctionError) function :hackney.start/0 is undefined or private. Did you mean one of:
      * start_response/1
    (hackney) :hackney.start()
    (excoveralls) lib/excoveralls/poster.ex:25: ExCoveralls.Poster.send_file/2
    (excoveralls) lib/excoveralls/poster.ex:13: ExCoveralls.Poster.execute/2
    (mix) lib/mix/tasks/test.ex:245: Mix.Tasks.Test.run/1
    (mix) lib/mix/task.ex:294: Mix.Task.run_task/3
    (mix) lib/mix/task.ex:326: Mix.Task.run_alias/3
    (mix) lib/mix/task.ex:259: Mix.Task.run/2
    (excoveralls) lib/mix/tasks.ex:54: Mix.Tasks.Coveralls.do_run/2
    (mix) lib/mix/task.ex:294: Mix.Task.run_task/3
    (mix) lib/mix/cli.ex:58: Mix.CLI.run_task/2
    (elixir) lib/code.ex:370: Code.require_file/2
The command "mix coveralls.travis --exclude pending" exited with 1.

mix.lock: https://github.com/Nebo15/digital_signature.api/blob/62fa1b688dfabb542400b7ef110e18dab50caa44/mix.lock

[cabol]

I'm having the same issue with mix coveralls.travis, what I've found is it might be because the hackney dependency hasn't been updated in your mix.lock, currently is locked to 1.6.5 and your project works. But in this case that we use excoveralls as dependency, hackney version 1.8.4 is fetched and then the error comes up:

** (UndefinedFunctionError) function :hackney.start/0 is undefined or private. Did you mean one of:

      * start_response/1

    :hackney.start()
    lib/excoveralls/poster.ex:25: ExCoveralls.Poster.send_file/2
    lib/excoveralls/poster.ex:13: ExCoveralls.Poster.execute/2
    (mix) lib/mix/tasks/test.ex:245: Mix.Tasks.Test.run/1
    (mix) lib/mix/task.ex:300: Mix.Task.run_task/3
    lib/mix/tasks.ex:54: Mix.Tasks.Coveralls.do_run/2
    (mix) lib/mix/task.ex:300: Mix.Task.run_task/3
    (mix) lib/mix/cli.ex:58: Mix.CLI.run_task/2
    (elixir) lib/code.ex:370: Code.require_file/2

This is the line that cause the error: https://github.com/parroty/excoveralls/blob/master/lib/excoveralls/poster.ex#L25

A possible fix might be replace that line by:

Application.ensure_all_started(:hackney)

Thanks, stay tuned!

[parroty]

Thanks for the report and analysis, I've tried to update the code as suggested (will push to hex too).