shush_backtraces breaks Minitest::Mock

[mattbrictson]

Monkey patching Kernel#raise in shush_backtraces causes Minitest::Mock to blow up with infinite recursion:

mock = Minitest::Mock.new
mock.expect(:meaning_of_life, 42)
mock.verify
SystemStackError: stack level too deep

Minitest::Mock is calling raise, which triggers method_missing, which calls raise, and on and on.

Somehow spring's redefinition of raise causes it to be added to Kernel.instance_methods (usually it is not there).

With spring loaded:

Kernel.instance_methods.include?(:raise)
=> true

Without spring loaded:

Kernel.instance_methods.include?(:raise)
=> false

This affects how Minitest::Mock does its magic, leading to the infinite recursion problem.

Is there another way shush_backtraces can be written that doesn't cause this problem?

Rails 4.1.5
Spring 1.1.3
Minitest 5.4.1
ruby 2.1.2p95

[mattbrictson]

I discovered the problem is that shush_backtraces was redefining Kernel.raise as a public method, when it should be private. My PR #351 fixes this issue.