How to make rake test not use the default minitest

Question

I am following along the Make your own Gem Guide from RubyGems. Executing the rake test instructions fails as follows:

> rake test
~/.rbenv/versions/2.1.2/lib/ruby/2.1.0/minitest/unit.rb:26:in `const_missing': uninitialized constant MiniTest::Test (NameError)
<rest of output truncated>

I figured that it is because the minitest version being used is 4.7.5 and not 5.6.0 (or any of the 5.0.0 series that is needed to have MiniTest::Test be valid). So I installed minitest 5.6.0 and now I have both versions of minitest. However rake test will still only use the 4.7.5 version.

How do I make it so that running rake test uses the right minitest within the setting of the Guide?

Using ruby directly works:

 > ruby -Ilib test/test_hola.rb
 Run options: --seed 48777

 # Running:

 ...

 Finished in 0.002862s, 1048.3550 runs/s, 1048.3550 assertions/s.

 3 runs, 3 assertions, 0 failures, 0 errors, 0 skips

Deleting minitest 4.7.5 is nigh impossible ;).

Setup

• Ruby 2.1.2 under rbenv 0.4.0-129-g7e0e85b
• rake (10.1.0)
• minitest (5.6.0, 4.7.5)
• Ubuntu 14.04

Edit

Adding gem "minitest" in Rakefile and/or test_hola.rb does not fix the issue.

Answer 1

The solution I used was to delete the old minitest directory located at: ~/.rbenv/versions/2.1.2/lib/ruby/2.1.0/minitest/.

Indeed, despite gem list minitest -d returning:

*** LOCAL GEMS ***

minitest (5.6.0, 4.7.5)
    Author: Ryan Davis
    Homepage: https://github.com/seattlerb/minitest
    License: MIT
    Installed at (5.6.0): ~/.rbenv/versions/2.1.2/lib/ruby/gems/2.1.0
                 (4.7.5, default): ~/.rbenv/versions/2.1.2/lib/ruby/gems/2.1.0

minitest provides a complete suite of testing facilities supporting
TDD, BDD, mocking, and benchmarking

the default minitest location was actually ~/.rbenv/versions/2.1.2/lib/ruby/2.1.0/minitest/. The reported location for the newer minitest (5.6.0 in this case) is correct.

Answer 2

And the following line to your Rakefile:

gem "minitest"