Fix an issue with a missing boolean coercion

lib/mixture.rb

@@ -27,6 +27,16 @@ module Mixture
   # @return [Proc{(Object) => Object}]
   Itself = proc { |value| value }
 
+  # A proc that returns true.
+  #
+  # @return [Proc{() => true}]
+  Prove = proc { true }
+
+  # A proc that returns false.
+  #
+  # @return [Proc{() => false}]
+  Refute = proc { false }
+
   # Finalizes all of the Mixture modules.
   #
   # @return [void]

lib/mixture/coerce/array.rb

@@ -7,6 +7,7 @@ class Array < Base
       type Types::Array
 
       coerce_to(Types::Object, Itself)
+      coerce_to(Types::Boolean, :any?)
 
       coerce_to(Types::Array) do |value, type|
         member = type.options.fetch(:members).first

lib/mixture/coerce/boolean.rb

@@ -0,0 +1,14 @@
+# encoding: utf-8
+
+module Mixture
+  module Coerce
+    # Handles coercion of the boolean classes.
+    class Boolean < Base
+      type Types::Array
+
+      coerce_to(Types::Object, Itself)
+      coerce_to(Types::Boolean, Itself)
+      coerce_to(Types::Integer) { |value| value ? 1 : 0 }
+    end
+  end
+end

lib/mixture/coerce/float.rb

@@ -11,6 +11,7 @@ class Float < Base
       coerce_to(Types::Float, Itself)
       coerce_to(Types::Integer, :to_i)
       coerce_to(Types::Rational, :to_r)
+      coerce_to(Types::Boolean) { |value| !value.zero? }
       coerce_to(Types::Time) { |value| ::Time.at(value) }
       coerce_to(Types::Date) { |value| ::Time.at(value).to_date }
       coerce_to(Types::DateTime) { |value| ::Time.at(value).to_datetime }

lib/mixture/coerce/hash.rb

@@ -7,6 +7,7 @@ class Hash < Base
       type Types::Hash
 
       coerce_to(Types::Object, Itself)
+      coerce_to(Types::Boolean, :any?)
 
       coerce_to(Types::Hash) do |value, type|
         members = type.options.fetch(:members)

lib/mixture/coerce/integer.rb

@@ -11,6 +11,7 @@ class Integer < Base
       coerce_to(Types::Float, :to_f)
       coerce_to(Types::Rational, :to_r)
       coerce_to(Types::Integer, Itself)
+      coerce_to(Types::Boolean) { |value| !value.zero? }
       coerce_to(Types::Time) { |value| ::Time.at(value) }
       coerce_to(Types::Date) { |value| ::Time.at(value).to_date }
       coerce_to(Types::DateTime) { |value| ::Time.at(value).to_datetime }

lib/mixture/coerce/nil.rb

@@ -8,6 +8,7 @@ class Nil < Base
 
       coerce_to(Types::Object, Itself)
       coerce_to(Types::Nil, Itself)
+      coerce_to(Types::Boolean, Refute)
       coerce_to(Types::String) { "" }
       coerce_to(Types::Array) { [] }
       coerce_to(Types::Float) { 0.0 }

lib/mixture/coerce/object.rb

@@ -22,6 +22,7 @@ class Object < Base
       end
 
       coerce_to(Types::Object, Itself)
+      coerce_to(Types::Boolean, Prove)
       coerce_to(Types::Array, TryMethods[:to_a, :to_ary, :to_array])
       coerce_to(Types::Date, TryMethods[:to_date])
       coerce_to(Types::DateTime, TryMethods[:to_datetime])

lib/mixture/coerce/rational.rb

@@ -8,6 +8,7 @@ class Rational < Base
 
       coerce_to(Types::Object, Itself)
       coerce_to(Types::Rational, Itself)
+      coerce_to(Types::Boolean) { |value| !value.zero? }
       coerce_to(Types::Time) { |value| ::Time.at(value) }
       coerce_to(Types::Date) { |value| ::Time.at(value).to_date }
       coerce_to(Types::DateTime) { |value| ::Time.at(value).to_datetime }

lib/mixture/coerce/set.rb

@@ -7,6 +7,7 @@ class Set < Base
       type Types::Set
 
       coerce_to(Types::Object, Itself)
+      coerce_to(Types::Boolean, :any?)
 
       coerce_to(Types::Set) do |value, type|
         member = type.options.fetch(:members).first

lib/mixture/coerce/string.rb

@@ -11,6 +11,7 @@ class String < Base
       coerce_to(Types::Symbol, :to_sym)
       coerce_to(Types::Integer, :to_i)
       coerce_to(Types::Float, :to_f)
+      coerce_to(Types::Boolean) { |value| !value.empty? }
       coerce_to(Types::Time) { |value| ::Time.parse(value) }
       coerce_to(Types::Date) { |value| ::Date.parse(value) }
       coerce_to(Types::DateTime) { |value| ::DateTime.parse(value) }

lib/mixture/types/boolean.rb

@@ -10,6 +10,7 @@ module Types
     class Boolean < Object
       register
       options[:primitive] = nil
+      options[:method] = :to_boolean
       as :bool, :boolean, true, false
 
       constraints.clear

lib/mixture/version.rb

@@ -5,5 +5,5 @@ module Mixture
   # The current version of Mixture.
   #
   # @return [String]
-  VERSION = "0.5.1"
+  VERSION = "0.6.0"
 end

spec/mixture/coerce/nil_spec.rb

@@ -0,0 +1,9 @@
+RSpec.describe Mixture::Coerce::Nil do
+  subject { described_class.instance }
+
+  it "performs coercions" do
+    expect(subject.to_integer.call(nil)).to be 0
+    expect(subject.to_boolean.call(nil)).to be false
+    expect(subject.to_string.call(nil)).to eq ""
+  end
+end

spec/mixture/coerce/object_spec.rb

@@ -7,6 +7,7 @@
   it "attempts coercion" do
     expect(subject.to_integer).to be_a Proc
     expect(subject.to_integer.call(value)).to be_an Integer
+    expect(subject.to_boolean.call(value)).to be true
   end
 
   it "tries multiple methods" do