Numericality validation of virtual attributes

Commit #18b2859d2522a4866c398b9a32ebc3de4ec79389 broke numericality
validation of virtual attributes in ActiveRecord models. This commit
added a `column_type` method that assumes if `columns_hash` is a thing
then our attribute would be present within it. This is not true for
virtual attributes and leads to:
```
     NoMethodError:
           undefined method `type' for nil:NilClass
         # /Users/bdmac/.gem/ruby/2.2.2/gems/shoulda-matchers-3.0.1/lib/shoulda/matchers/active_model/validate_numericality_of_matcher.rb:442:in
         # `column_type'
```

NEWS.md

@@ -17,6 +17,10 @@
   get a CouldNotSetAttributeError again.* (You may get some more information if
   a test fails, however.)
 
+* Fix `validate_numericality_of` so that it does not blow up when used against
+  a virtual attribute defined in an ActiveRecord model (that is, an attribute
+  that is not present in the database but is defined using `attr_accessor`).
+
 ### Improvements
 
 * Improve failure messages and descriptions of all matchers across the board so

lib/shoulda/matchers/active_model/validate_numericality_of_matcher.rb

@@ -491,7 +491,8 @@ module Shoulda
         end
 
         def given_numeric_column?
-          [:integer, :float, :decimal].include?(column_type)
+          attribute_is_active_record_column? &&
+            [:integer, :float, :decimal].include?(column_type)
         end
 
         private
@@ -512,9 +513,19 @@ module Shoulda
           )
         end
 
+        def attribute_is_active_record_column?
+          columns_hash.key?(@attribute.to_s)
+        end
+
         def column_type
+          columns_hash[@attribute.to_s].type
+        end
+
+        def columns_hash
           if @subject.class.respond_to?(:columns_hash)
-            @subject.class.columns_hash[@attribute.to_s].type
+            @subject.class.columns_hash
+          else
+            {}
           end
         end
 

spec/unit/shoulda/matchers/active_model/validate_numericality_of_matcher_spec.rb

@@ -152,6 +152,13 @@ Example did not properly validate that :attr looks like a number.
         }
       )
 
+      context 'when the attribute is a virtual attribute in an ActiveRecord model' do
+        it 'accepts' do
+          record = build_record_validating_numericality_of_virtual_attribute
+          expect(record).to validate_numericality
+        end
+      end
+
       context 'when the column is an integer column' do
         it 'accepts (and does not raise an AttributeChangedValueError)' do
           record = build_record_validating_numericality(column_type: :integer)
@@ -360,6 +367,15 @@ Example did not properly validate that :attr looks like an odd number.
         end
       end
 
+      context 'when the attribute is a virtual attribute in ActiveRecord model' do
+        it 'accepts' do
+          record = build_record_validating_numericality_of_virtual_attribute(
+            odd: true
+          )
+          expect(record).to validate_numericality.odd
+        end
+      end
+
       context 'when the column is an integer column' do
         it 'accepts (and does not raise an error)' do
           record = build_record_validating_numericality(
@@ -453,6 +469,15 @@ Example did not properly validate that :attr looks like an even number.
         end
       end
 
+      context 'when the attribute is a virtual attribute in an ActiveRecord model' do
+        it 'accepts' do
+          record = build_record_validating_numericality_of_virtual_attribute(
+            even: true,
+          )
+          expect(record).to validate_numericality.even
+        end
+      end
+
       context 'when the column is an integer column' do
         it 'accepts (and does not raise an error)' do
           record = build_record_validating_numericality(
@@ -551,6 +576,15 @@ than or equal to 18.
         end
       end
 
+      context 'when the attribute is a virtual attribute in an ActiveRecord model' do
+        it 'accepts' do
+          record = build_record_validating_numericality_of_virtual_attribute(
+            less_than_or_equal_to: 18,
+          )
+          expect(record).to validate_numericality.is_less_than_or_equal_to(18)
+        end
+      end
+
       context 'when the column is an integer column' do
         it 'accepts (and does not raise an error)' do
           record = build_record_validating_numericality(
@@ -648,6 +682,15 @@ than 18.
         end
       end
 
+      context 'when the attribute is a virtual attribute in an ActiveRecord model' do
+        it 'accepts' do
+          record = build_record_validating_numericality_of_virtual_attribute(
+            less_than: 18,
+          )
+          expect(record).to validate_numericality.is_less_than(18)
+        end
+      end
+
       context 'when the column is an integer column' do
         it 'accepts (and does not raise an error)' do
           record = build_record_validating_numericality(
@@ -743,6 +786,15 @@ to 18.
         end
       end
 
+      context 'when the attribute is a virtual attribute in an ActiveRecord model' do
+        it 'accepts' do
+          record = build_record_validating_numericality_of_virtual_attribute(
+            equal_to: 18,
+          )
+          expect(record).to validate_numericality.is_equal_to(18)
+        end
+      end
+
       context 'when the column is an integer column' do
         it 'accepts (and does not raise an error)' do
           record = build_record_validating_numericality(
@@ -841,6 +893,16 @@ than or equal to 18.
         end
       end
 
+      context 'when the attribute is a virtual attribute in an ActiveRecord model' do
+        it 'accepts' do
+          record = build_record_validating_numericality_of_virtual_attribute(
+            greater_than_or_equal_to: 18,
+          )
+          expect(record).to validate_numericality.
+            is_greater_than_or_equal_to(18)
+        end
+      end
+
       context 'when the column is an integer column' do
         it 'accepts (and does not raise an error)' do
           record = build_record_validating_numericality(
@@ -942,6 +1004,15 @@ than 18.
         end
       end
 
+      context 'when the attribute is a virtual attribute in an ActiveRecord model' do
+        it 'accepts' do
+          record = build_record_validating_numericality_of_virtual_attribute(
+            greater_than: 18,
+          )
+          expect(record).to validate_numericality.is_greater_than(18)
+        end
+      end
+
       context 'when the column is an integer column' do
         it 'accepts (and does not raise an error)' do
           record = build_record_validating_numericality(
@@ -1715,6 +1786,19 @@ Example did not properly validate that :attr looks like a number.
     end
   end
 
+  def define_model_validating_numericality_of_virtual_attribute(options = {})
+    attribute_name = options.delete(:attribute_name) { self.attribute_name }
+
+    define_model 'Example' do |model|
+      model.send(:attr_accessor, attribute_name)
+      model.validates_numericality_of(attribute_name, options)
+    end
+  end
+
+  def build_record_validating_numericality_of_virtual_attribute(options = {})
+    define_model_validating_numericality_of_virtual_attribute(options).new
+  end
+
   def build_record_validating_numericality(options = {})
     define_model_validating_numericality(options).new
   end