Add test generator for "binary" exercise (#394)

Automatically generate "binary" exercise tests

bin/generate-binary

@@ -0,0 +1,7 @@
+#!/usr/bin/env ruby
+
+require_relative '../lib/helper'
+require 'generator'
+require 'binary_cases'
+
+Generator.new('binary', BinaryCases).generate

exercises/binary/.version

@@ -0,0 +1 @@
+2

exercises/binary/binary_test.rb

@@ -1,14 +1,19 @@
 #!/usr/bin/env ruby
+# encoding: utf-8
 gem 'minitest', '>= 5.0.0'
 require 'minitest/autorun'
 require_relative 'binary'
 
+# Test data version:
+# dd43e66
 class BinaryTest < Minitest::Test
   def test_binary_0_is_decimal_0
+    # skip
     assert_equal 0, Binary.new('0').to_decimal
   end
 
   def test_binary_1_is_decimal_1
+    skip
     assert_equal 1, Binary.new('1').to_decimal
   end
 
@@ -47,23 +52,37 @@ def test_binary_ignores_leading_zeros
     assert_equal 31, Binary.new('000011111').to_decimal
   end
 
-  def test_invalid_binary_numbers_raise_an_error
+  def test_numbers_other_than_one_and_zero_raise_an_error
+    skip
+    %w(012 2).each do |input|
+      assert_raises(ArgumentError) { Binary.new(input) }
+    end
+  end
+
+  def test_containing_letters_raises_an_error
     skip
-    %w(012 10nope nope10 10nope10 001\ nope 2).each do |input|
-      assert_raises ArgumentError do
-        Binary.new(input)
-      end
+    %w(10nope nope10 10nope10 001\ nope).each do |input|
+      assert_raises(ArgumentError) { Binary.new(input) }
     end
   end
 
-  # Problems in exercism evolve over time,
-  # as we find better ways to ask questions.
+  # Problems in exercism evolve over time, as we find better ways to ask
+  # questions.
   # The version number refers to the version of the problem you solved,
   # not your solution.
   #
-  # Define a constant named VERSION inside of BookKeeping.
-  # If you're curious, read more about constants on RubyDoc:
+  # Define a constant named VERSION inside of the top level BookKeeping
+  # module, which may be placed near the end of your file.
+  #
+  # In your file, it will look like this:
+  #
+  # module BookKeeping
+  #   VERSION = 1 # Where the version number matches the one in the test.
+  # end
+  #
+  # If you are curious, read more about constants on RubyDoc:
   # http://ruby-doc.org/docs/ruby-doc-bundle/UsersGuide/rg/constants.html
+
   def test_bookkeeping
     skip
     assert_equal 2, BookKeeping::VERSION

exercises/binary/example.tt

@@ -0,0 +1,20 @@
+#!/usr/bin/env ruby
+# encoding: utf-8
+gem 'minitest', '>= 5.0.0'
+require 'minitest/autorun'
+require_relative 'binary'
+
+# Test data version:
+# <%= sha1 %>
+class BinaryTest < Minitest::Test<% test_cases.each do |test_case| %>
+  def <%= test_case.name %>
+    <%= test_case.skipped %>
+    <%= test_case.assertion %>
+  end
+<% end %>
+<%= IO.read(XRUBY_LIB + '/bookkeeping.md') %>
+  def test_bookkeeping
+    skip
+    assert_equal <%= version.next %>, BookKeeping::VERSION
+  end
+end

lib/binary_cases.rb

@@ -0,0 +1,65 @@
+class BinaryCase < OpenStruct
+  def name
+    'test_%s' % description.gsub(/[ -]/, '_')
+  end
+
+  def assertion
+    return compound_assertion if multiple_assertions?
+    Assertion.new("'#{binary}'", expected).to_s
+  end
+
+  def skipped
+    index.zero? ? '# skip' : 'skip'
+  end
+
+  private
+
+  def multiple_assertions?
+    binary.is_a?(Array)
+  end
+
+  def compound_assertion
+    inputs = binary.map { |e| e.gsub(' ', '\ ') }.join(' ')
+    %(%w(#{inputs}).each do |input|
+      #{Assertion.new('input', expected)}
+    end)
+  end
+
+  class Assertion
+    def initialize(initialization_value, expected)
+      @initialization_value = initialization_value
+      @expected = expected
+    end
+
+    def to_s
+      return error_assertion if raises_error?
+      equality_assertion
+    end
+
+    private
+
+    attr_reader :initialization_value, :expected
+
+    def error_assertion
+      "assert_raises(ArgumentError) { #{work_load} }"
+    end
+
+    def equality_assertion
+      "assert_equal #{expected}, #{work_load}"
+    end
+
+    def work_load
+      "Binary.new(#{initialization_value})#{'.to_decimal' unless raises_error?}"
+    end
+
+    def raises_error?
+      expected.to_i == -1
+    end
+  end
+end
+
+BinaryCases = proc do |data|
+  JSON.parse(data)['decimal'].map.with_index do |row, i|
+    BinaryCase.new(row.merge('index' => i))
+  end
+end