minitest-shouldify

This is a bad idea.

The Problem

So you want to use minitest, but you are familiar with Rspec and don't like change to must/wont from should/should_not.

The Solution

First, require minitest-shouldify in your test_helper.rb file:

require "minitest/shouldify"

Second, register your desired expectation names:

Minitest::Shouldify.register! "should", "should_not"

Now you are ready to use the new names:

describe Foo, :bar do
  it "is bar" do
    Foo.new.bar.should_equal "bar"
  end

  it "isn't baz" do
    Foo.new.bar.should_not_equal "baz"
  end
end

Also, if you are using minitest-matchers and have defined a be_equal_to matcher you could also use this syntax:

describe Foo, :bar do
  subject { Foo.new.bar }

  it { should     be_equal_to("bar") }
  it { should_not be_equal_to("baz") }

  should     { be_equal_to("bar") }
  should_not { be_equal_to("baz") }
end

Why “must”

Its a fair question, after all the method “should” is common in BDD-style specs. Its also not uncommon for technical specifications to have guidelines similar to the following:

The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in [RFC2119].

So let's take a look at RFC2119:

1. MUST   This word, or the terms "REQUIRED" or "SHALL", mean that the
   definition is an absolute requirement of the specification.

2. MUST NOT   This phrase, or the phrase "SHALL NOT", mean that the
   definition is an absolute prohibition of the specification.

3. SHOULD   This word, or the adjective "RECOMMENDED", mean that there
   may exist valid reasons in particular circumstances to ignore a
   particular item, but the full implications must be understood and
   carefully weighed before choosing a different course.

4. SHOULD NOT   This phrase, or the phrase "NOT RECOMMENDED" mean that
   there may exist valid reasons in particular circumstances when the
   particular behavior is acceptable or even useful, but the full
   implications should be understood and the case carefully weighed
   before implementing any behavior described with this label.

This clearly states that MUST is a requirement, and SHOULD is a recommendation. However, your testing framework doesn't have the context to know under which circumstances the tests are allowed to fail. So since you are asserting hard requirements anyway, you might as well use the proper vocabulary.

Wait. Then why “wont”?

Yes, minitest could have chosen to name the expectations must and must_not. But, there are reasons to prefer wont over must_not. One advantage is that must and wont are the same number of characters, just as assert and refute are.

If you don't like it you can always change it:

Minitest::Shouldify.register! "must", "must_not"

Disclaimer

No really, its probably not a good idea to use this.

License

(The MIT License)

Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the 'Software'), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED 'AS IS', WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.