minitest block testing

foo_rspec.rb

#!/usr/bin/env rspec

class Foo
  def foo!
    File.open("foo.txt", "w") do |f|
      f.write "hello!"
    end
  end
end

describe Foo do

  let(:foo){ Foo.new }
  let(:file){ double(:file) }

  it "should call foo" do
    File.should_receive(:open).with("foo.txt", "w").and_yield(file)
    file.should_receive(:write).with("hello!")
    foo.foo!
  end
end

foo_spec.rb

#!/usr/bin/env ruby -w

require 'rubygems'
require 'minitest/autorun'

class Foo
  def foo!
    File.open("foo.txt", "w") do |f|
      f.write "hello!"
      raise "I'm not tested!!"
    end
  end
end

describe Foo do

  let(:foo){ Foo.new }
  let(:file){ Minitest::Mock.new }

  it "should call foo" do
    File.stub(:open, file) do
      foo.foo!
    end
  end
end