Add #on qualifier to numericality matcher

This is present in all other matchers through ValidationMatcher.
However, ValidateNumericalityOfMatcher does not inherit from
ValidationMatcher. (This happens to be okay, since
ValidateNumericalityOfMatcher contains submatchers and we have to make
sure to pass the context all the way through.)

Hat tip @sj26 for most of the content of this commit, as well as
@anujbiyani for another approach to this.

NEWS.md

@@ -70,6 +70,8 @@
 
 * Add `strict` qualifier to `validate_numericality_of`. ([#620])
 
+* Add `on` qualifier to `validate_numericality_of`. (h/t [#356], [#358])
+
 [#402]: https://github.com/thoughtbot/shoulda-matchers/pull/402
 [#587]: https://github.com/thoughtbot/shoulda-matchers/pull/587
 [#662]: https://github.com/thoughtbot/shoulda-matchers/pull/662
@@ -82,6 +84,8 @@
 [#677]: https://github.com/thoughtbot/shoulda-matchers/pull/677
 [#620]: https://github.com/thoughtbot/shoulda-matchers/pull/620
 [#693]: https://github.com/thoughtbot/shoulda-matchers/pull/693
+[#356]: https://github.com/thoughtbot/shoulda-matchers/pull/356
+[#358]: https://github.com/thoughtbot/shoulda-matchers/pull/358
 
 # 2.8.0
 

lib/shoulda/matchers/active_model/numericality_matchers/numeric_type_matcher.rb

@@ -22,6 +22,11 @@ module Shoulda
             self
           end
 
+          def on(context)
+            @disallow_value_matcher.on(context)
+            self
+          end
+
           def allowed_type
             raise NotImplementedError
           end

lib/shoulda/matchers/active_model/validate_numericality_of_matcher.rb

@@ -384,6 +384,11 @@ module Shoulda
           self
         end
 
+        def on(context)
+          @submatchers.each { |matcher| matcher.on(context) }
+          self
+        end
+
         def matches?(subject)
           @subject = subject
           failing_submatchers.empty?

spec/unit/shoulda/matchers/active_model/numericality_matchers/comparison_matcher_spec.rb

@@ -197,6 +197,26 @@ describe Shoulda::Matchers::ActiveModel::NumericalityMatchers::ComparisonMatcher
     end
   end
 
+  context 'qualified with on and validating with on' do
+    it 'accepts' do
+      expect(instance_with_validations(on: :customizable)).
+        to matcher.on(:customizable)
+    end
+  end
+
+  context 'qualified with on but not validating with on' do
+    it 'accepts since the validation never considers a context' do
+      expect(instance_with_validations).to matcher.on(:customizable)
+    end
+  end
+
+  context 'not qualified with on but validating with on' do
+    it 'rejects since the validation never runs' do
+      expect(instance_with_validations(on: :customizable)).
+        not_to matcher
+    end
+  end
+
   describe '#comparison_description' do
     [{ operator: :>, value: 0, expectation: 'greater than 0' },
      { operator: :>=, value: -1.0, expectation: 'greater than or equal to -1.0' },

spec/unit/shoulda/matchers/active_model/numericality_matchers/even_number_matcher_spec.rb

@@ -64,6 +64,26 @@ describe Shoulda::Matchers::ActiveModel::NumericalityMatchers::EvenNumberMatcher
     end
   end
 
+  context 'qualified with on and validating with on' do
+    it 'accepts' do
+      expect(validating_even_number(on: :customizable)).
+        to subject.on(:customizable)
+    end
+  end
+
+  context 'qualified with on but not validating with on' do
+    it 'accepts since the validation never considers a context' do
+      expect(validating_even_number).to subject.on(:customizable)
+    end
+  end
+
+  context 'not qualified with on but validating with on' do
+    it 'rejects since the validation never runs' do
+      expect(validating_even_number(on: :customizable)).
+        not_to subject
+    end
+  end
+
   def validating_even_number(options = {})
     define_model :example, attr: :string do
       validates_numericality_of :attr, { even: true }.merge(options)

spec/unit/shoulda/matchers/active_model/numericality_matchers/odd_number_matcher_spec.rb

@@ -64,6 +64,26 @@ describe Shoulda::Matchers::ActiveModel::NumericalityMatchers::OddNumberMatcher
     end
   end
 
+  context 'qualified with on and validating with on' do
+    it 'accepts' do
+      expect(validating_odd_number(on: :customizable)).
+        to subject.on(:customizable)
+    end
+  end
+
+  context 'qualified with on but not validating with on' do
+    it 'accepts since the validation never considers a context' do
+      expect(validating_odd_number).to subject.on(:customizable)
+    end
+  end
+
+  context 'not qualified with on but validating with on' do
+    it 'rejects since the validation never runs' do
+      expect(validating_odd_number(on: :customizable)).
+        not_to subject
+    end
+  end
+
   def validating_odd_number(options = {})
     define_model :example, attr: :string do
       validates_numericality_of :attr, { odd: true }.merge(options)

spec/unit/shoulda/matchers/active_model/numericality_matchers/only_integer_matcher_spec.rb

@@ -64,6 +64,26 @@ describe Shoulda::Matchers::ActiveModel::NumericalityMatchers::OnlyIntegerMatche
     end
   end
 
+  context 'qualified with on and validating with on' do
+    it 'accepts' do
+      expect(validating_only_integer(on: :customizable)).
+        to subject.on(:customizable)
+    end
+  end
+
+  context 'qualified with on but not validating with on' do
+    it 'accepts since the validation never considers a context' do
+      expect(validating_only_integer).to subject.on(:customizable)
+    end
+  end
+
+  context 'not qualified with on but validating with on' do
+    it 'rejects since the validation never runs' do
+      expect(validating_only_integer(on: :customizable)).
+        not_to subject
+    end
+  end
+
   def validating_only_integer(options = {})
     define_model :example, attr: :string do
       validates_numericality_of :attr, { only_integer: true }.merge(options)

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

@@ -55,6 +55,12 @@ describe Shoulda::Matchers::ActiveModel::ValidateNumericalityOfMatcher, type: :m
           name: :only_integer,
           validation_name: :only_integer,
           validation_value: true,
+        },
+        {
+          name: :on,
+          argument: :customizable,
+          validation_name: :on,
+          validation_value: :customizable
         }
       ]
     end
@@ -454,6 +460,32 @@ describe Shoulda::Matchers::ActiveModel::ValidateNumericalityOfMatcher, type: :m
     end
   end
 
+  context 'qualified with on and validating with on' do
+    it 'accepts' do
+      record = build_record_validating_numericality(on: :customizable)
+      expect(record).to validate_numericality.on(:customizable)
+    end
+  end
+
+  context 'qualified with on but not validating with on' do
+    it 'accepts since the validation never considers a context' do
+      record = build_record_validating_numericality
+      expect(record).to validate_numericality.on(:customizable)
+    end
+  end
+
+  context 'not qualified with on but validating with on' do
+    it 'rejects since the validation never runs' do
+      record = build_record_validating_numericality(on: :customizable)
+      assertion = lambda do
+        expect(record).to validate_numericality
+      end
+      expect(&assertion).to fail_with_message_including(
+        'Expected errors to include "is not a number"'
+      )
+    end
+  end
+
   context 'with combinations of qualifiers together' do
     all_qualifier_combinations.each do |combination|
       if combination.size > 1
@@ -778,7 +810,8 @@ describe Shoulda::Matchers::ActiveModel::ValidateNumericalityOfMatcher, type: :m
   end
 
   def define_model_validating_numericality(options = {})
-    attribute_name = options.fetch(:attribute_name) { self.attribute_name }
+    attribute_name = options.delete(:attribute_name) { self.attribute_name }
+
     define_model 'Example', attribute_name => :string do |model|
       model.validates_numericality_of(attribute_name, options)
     end