Added QueryAttributes, closes #3

CHANGELOG.md

@@ -1,6 +1,7 @@
 # ActiveAttr 0.3.0 (unreleased) #
 
 * Added BlockInitialization
+* Added QueryAttributes
 * Added UnknownAttributeError
 * Attributes now honors getters/setters when calling #read_attribute,
   #write_attribute, #[], and #[]=

README.md

@@ -79,6 +79,23 @@ attribute.
     person.first_name #=> "Chris"
     person.last_name #=> "Griego"
 
+### QueryAttributes ###
+
+Including the QueryAttributes module into your class builds on Attributes by
+providing instance methods for querying your attributes
+
+    class Person
+      include ActiveAttr::QueryAttributes
+
+      attribute :first_name
+      attribute :last_name
+    end
+
+    person = Person.new
+    person.first_name = "Chris"
+    person.first_name? #=> true
+    person.last_name? #=> false
+
 ## RSpec Integration ##
 
 ActiveAttr comes with matchers and RSpec integration to assist you in testing

lib/active_attr.rb

@@ -14,6 +14,7 @@ module ActiveAttr
   autoload :ChainableInitialization
   autoload :Error
   autoload :MassAssignment
+  autoload :QueryAttributes
   autoload :StrictMassAssignment
   autoload :UnknownAttributeError
   autoload :UnknownAttributesError

lib/active_attr/query_attributes.rb

@@ -0,0 +1,60 @@
+require "active_attr/attributes"
+require "active_attr/unknown_attribute_error"
+require "active_support/concern"
+require "active_support/core_ext/object/blank"
+
+module ActiveAttr
+  # QueryAttributes provides instance methods for querying attributes.
+  #
+  # @example Usage
+  #   class Person
+  #     include ActiveAttr::QueryAttributes
+  #     attribute :name
+  #   end
+  #
+  #   person = Person.new
+  #   person.name? #=> false
+  #   person.name = "Chris Griego"
+  #   person.name? #=> true
+  #
+  # @since 0.3.0
+  module QueryAttributes
+    extend ActiveSupport::Concern
+    include Attributes
+
+    included do
+      attribute_method_suffix "?"
+    end
+
+    # Test the presence of an attribute
+    #
+    # Similar to an ActiveRecord model, when the attribute is a zero value or
+    # is a string that represents false, the method returns false.
+    #
+    # @example Query an attribute
+    #   person.query_attribute(:name)
+    #
+    # @param [String, Symbol, #to_s] name The name of the attribute to query
+    #
+    # @return [true, false] The presence of the attribute
+    #
+    # @since 0.3.0
+    def query_attribute(name)
+      if respond_to? "#{name}?"
+        send "#{name}?"
+      else
+        raise UnknownAttributeError, "unknown attribute: #{name}"
+      end
+    end
+
+    private
+
+    def attribute?(name)
+      case value = read_attribute(name)
+      when "false", "FALSE", "f", "F" then false
+      when Numeric, /^\-?[0-9]/ then !value.to_f.zero?
+      else value.present?
+      end
+    end
+  end
+end

spec/unit/active_attr/attributes_spec.rb

@@ -80,7 +80,7 @@ def self.name
         subject.amount = 1
       end
 
-      it "defining an attribute twice does not make appear in the" do
+      it "defining an attribute twice does not give the class two attribute definitions" do
         Class.new do
           include Attributes
           attribute :name

spec/unit/active_attr/query_attributes_spec.rb

@@ -0,0 +1,225 @@
+require "spec_helper"
+require "active_attr/query_attributes"
+require "bigdecimal"
+
+module ActiveAttr
+  describe QueryAttributes do
+    subject { model_class.new }
+
+    let :model_class do
+      Class.new do
+        include QueryAttributes
+
+        attribute :value
+        attribute :overridden
+
+        def overridden?
+          super
+        end
+
+        def true?
+          true
+        end
+
+        def false?
+          false
+        end
+      end
+    end
+
+    describe ".attribute" do
+      it "defines an attribute predicate method that calls #attribute?" do
+        subject.should_receive(:attribute?).with("value")
+        subject.value?
+      end
+
+      it "defines an attribute reader that can be called via super" do
+        subject.should_receive(:attribute?).with("overridden")
+        subject.overridden?
+      end
+    end
+
+    describe "#query_attribute" do
+      it "raises ArgumentError when called with two arguments" do
+        expect { subject.query_attribute(:a, :b) }.to raise_error ArgumentError
+      end
+
+      it "does not raise when called with a single argument" do
+        expect { subject.query_attribute(:a) }.not_to raise_error ArgumentError
+      end
+
+      it "raises ArgumentError when called with no arguments" do
+        expect { subject.query_attribute }.to raise_error ArgumentError
+      end
+
+      it "calls the predicate method if defined" do
+        subject.query_attribute(:true).should == true
+        subject.query_attribute(:false).should == false
+      end
+
+      it "raises when getting an undefined attribute" do
+        expect { subject.query_attribute(:initials) }.to raise_error UnknownAttributeError, "unknown attribute: initials"
+      end
+
+      it "is false when the attribute is false" do
+        subject.value = false
+        subject.value?.should == false
+      end
+
+      it "is true when the attribute is true" do
+        subject.value = true
+        subject.value?.should == true
+      end
+
+      it "is false when the attribute is nil" do
+        subject.value = nil
+        subject.value?.should == false
+      end
+
+      it "is true when the attribute is an Object" do
+        subject.value = Object.new
+        subject.value?.should == true
+      end
+
+      it "is false when the attribute is an empty string" do
+        subject.value = ""
+        subject.value?.should == false
+      end
+
+      it "is true when the attribute is a non-empty string" do
+        subject.value = "Chris"
+        subject.value?.should == true
+      end
+
+      it "is false when the attribute is 0" do
+        subject.value = 0
+        subject.value?.should == false
+      end
+
+      it "is true when the attribute is 1" do
+        subject.value = 1
+        subject.value?.should == true
+      end
+
+      it "is false when the attribute is 0.0" do
+        subject.value = 0.0
+        subject.value?.should == false
+      end
+
+      it "is true when the attribute is 0.1" do
+        subject.value = 0.1
+        subject.value?.should == true
+      end
+
+      it "is false when the attribute is a zero BigDecimal" do
+        subject.value = BigDecimal.new("0.0")
+        subject.value?.should == false
+      end
+
+      it "is true when the attribute is a non-zero BigDecimal" do
+        subject.value = BigDecimal.new("0.1")
+        subject.value?.should == true
+      end
+
+      it "is true when the attribute is -1" do
+        subject.value = -1
+        subject.value?.should == true
+      end
+
+      it "is false when the attribute is -0.0" do
+        subject.value = -0.0
+        subject.value?.should == false
+      end
+
+      it "is true when the attribute is -0.1" do
+        subject.value = -0.1
+        subject.value?.should == true
+      end
+
+      it "is false when the attribute is a negative zero BigDecimal" do
+        subject.value = BigDecimal.new("-0.0")
+        subject.value?.should == false
+      end
+
+      it "is true when the attribute is a negative BigDecimal" do
+        subject.value = BigDecimal.new("-0.1")
+        subject.value?.should == true
+      end
+
+      it "is false when the attribute is '0'" do
+        subject.value = "0"
+        subject.value?.should == false
+      end
+
+      it "is true when the attribute is '1'" do
+        subject.value = "1"
+        subject.value?.should == true
+      end
+
+      it "is false when the attribute is '0.0'" do
+        subject.value = "0.0"
+        subject.value?.should == false
+      end
+
+      it "is true when the attribute is '0.1'" do
+        subject.value = "0.1"
+        subject.value?.should == true
+      end
+
+      it "is true when the attribute is '-1'" do
+        subject.value = "-1"
+        subject.value?.should == true
+      end
+
+      it "is false when the attribute is '-0.0'" do
+        subject.value = "-0.0"
+        subject.value?.should == false
+      end
+
+      it "is true when the attribute is '-0.1'" do
+        subject.value = "-0.1"
+        subject.value?.should == true
+      end
+
+      it "is true when the attribute is 'true'" do
+        subject.value = "true"
+        subject.value?.should == true
+      end
+
+      it "is false when the attribute is 'false'" do
+        subject.value = "false"
+        subject.value?.should == false
+      end
+
+      it "is true when the attribute is 't'" do
+        subject.value = "t"
+        subject.value?.should == true
+      end
+
+      it "is false when the attribute is 'f'" do
+        subject.value = "f"
+        subject.value?.should == false
+      end
+
+      it "is true when the attribute is 'T'" do
+        subject.value = "T"
+        subject.value?.should == true
+      end
+
+      it "is false when the attribute is 'F'" do
+        subject.value = "F"
+        subject.value?.should == false
+      end
+
+      it "is true when the attribute is 'TRUE'" do
+        subject.value = "TRUE"
+        subject.value?.should == true
+      end
+
+      it "is false when the attribute is 'FALSE" do
+        subject.value = "FALSE"
+        subject.value?.should == false
+      end
+    end
+  end
+end