Introduce testing

[schneems]

As a testing strategy we'll generate apps that pretend to be buildpacks using the "inline" buildpack. We can then use this along with Hatchet to test our buildpack behavior.

Adding in these tests exposed a problem with the previous logic. There was a bug where if a Procfile existed but didn't contain a release: designation then the runtime check wouldn't be executed.

[schneems]

This accidentally runs all tests against master branch. Need to also include this commit: e76ff1a

[schneems]

Rspec will truncate output if it is too long. You can set it to not do this by configuring:

  config.expect_with :rspec do |c|
    c.max_formatted_output_length = Float::INFINITY
    c.syntax = :expect
  end

I'm also asking how to disable inspect-ing the output of the tests at rspec/rspec-expectations#1188