Remove customised error message

We're now handling these values on the frontend, so can keep this simple.

fixes up:
 Add numericality validation for *
 Add translation for Active Record error message

app/models/calculator/flat_percent_item_total.rb

@@ -5,7 +5,7 @@ module Calculator
     preference :flat_percent, :decimal, default: 0
 
     validates :preferred_flat_percent,
-              numericality: { message: :calculator_preferred_value_error }
+              numericality: true
 
     def self.description
       Spree.t(:flat_percent)

app/models/calculator/flat_percent_per_item.rb

@@ -9,7 +9,7 @@ class Calculator::FlatPercentPerItem < Spree::Calculator
   preference :flat_percent, :decimal, default: 0
 
   validates :preferred_flat_percent,
-            numericality: { message: :calculator_preferred_value_error }
+            numericality: true
 
   def self.description
     I18n.t(:flat_percent_per_item)

app/models/calculator/flat_rate.rb

@@ -5,7 +5,7 @@ module Calculator
     preference :amount, :decimal, default: 0
 
     validates :preferred_amount,
-              numericality: { message: :calculator_preferred_value_error }
+              numericality: true
 
     def self.description
       I18n.t(:flat_rate_per_order)

app/models/calculator/flexi_rate.rb

@@ -8,7 +8,7 @@ module Calculator
 
     validates :preferred_first_item,
               :preferred_additional_item,
-              numericality: { message: :calculator_preferred_value_error }
+              numericality: true
 
     def self.description
       I18n.t(:flexible_rate)

app/models/calculator/per_item.rb

@@ -5,7 +5,7 @@ module Calculator
     preference :amount, :decimal, default: 0
 
     validates :preferred_amount,
-              numericality: { message: :calculator_preferred_value_error }
+              numericality: true
 
     def self.description
       I18n.t(:flat_rate_per_item)

app/models/calculator/price_sack.rb

@@ -9,7 +9,7 @@ module Calculator
     validates :preferred_minimal_amount,
               :preferred_normal_amount,
               :preferred_discount_amount,
-              numericality: { message: :calculator_preferred_value_error }
+              numericality: true
 
     def self.description
       I18n.t(:price_sack)

config/locales/en.yml

@@ -91,8 +91,6 @@ en:
         preferred_unit_from_list: "Calculator Unit From List:"
         preferred_per_unit: "Calculator Per Unit:"
     errors:
-      messages:
-        calculator_preferred_value_error: "Invalid input. Please use only numbers. For example: 10, 5.5, -20"
       models:
         spree/user:
           attributes:

spec/models/calculator/flat_percent_item_total_spec.rb

@@ -8,10 +8,7 @@ describe Calculator::FlatPercentItemTotal do
 
   before { allow(calculator).to receive_messages preferred_flat_percent: 10 }
 
-  it do
-    should validate_numericality_of(:preferred_flat_percent).
-      with_message("Invalid input. Please use only numbers. For example: 10, 5.5, -20")
-  end
+  it { is_expected.to validate_numericality_of(:preferred_flat_percent) }
 
   it "computes amount correctly for a single line item" do
     expect(calculator.compute(line_item)).to eq(1.0)

spec/models/calculator/flat_percent_per_item_spec.rb

@@ -5,10 +5,7 @@ require 'spec_helper'
 describe Calculator::FlatPercentPerItem do
   let(:calculator) { Calculator::FlatPercentPerItem.new preferred_flat_percent: 20 }
 
-  it do
-    should validate_numericality_of(:preferred_flat_percent).
-      with_message("Invalid input. Please use only numbers. For example: 10, 5.5, -20")
-  end
+  it { is_expected.to validate_numericality_of(:preferred_flat_percent) }
 
   it "calculates for a simple line item" do
     line_item = Spree::LineItem.new price: 50, quantity: 2

spec/models/calculator/flat_rate_spec.rb

@@ -7,8 +7,5 @@ describe Calculator::FlatRate do
 
   before { allow(calculator).to receive_messages preferred_amount: 10 }
 
-  it do
-    should validate_numericality_of(:preferred_amount).
-      with_message("Invalid input. Please use only numbers. For example: 10, 5.5, -20")
-  end
+  it { is_expected.to validate_numericality_of(:preferred_amount) }
 end

spec/models/calculator/flexi_rate_spec.rb

@@ -12,15 +12,8 @@ describe Calculator::FlexiRate do
     )
   end
 
-  it do
-    should validate_numericality_of(:preferred_first_item).
-      with_message("Invalid input. Please use only numbers. For example: 10, 5.5, -20")
-  end
-
-  it do
-    should validate_numericality_of(:preferred_additional_item).
-      with_message("Invalid input. Please use only numbers. For example: 10, 5.5, -20")
-  end
+  it { is_expected.to validate_numericality_of(:preferred_first_item) }
+  it { is_expected.to validate_numericality_of(:preferred_additional_item) }
 
   context 'when nb of items ordered is above preferred max' do
     let(:quantity) { 4.0 }

spec/models/calculator/per_item_spec.rb

@@ -7,10 +7,7 @@ describe Calculator::PerItem do
   let(:shipping_calculable) { double(:calculable) }
   let(:line_item) { build_stubbed(:line_item, quantity: 5) }
 
-  it do
-    should validate_numericality_of(:preferred_amount).
-      with_message("Invalid input. Please use only numbers. For example: 10, 5.5, -20")
-  end
+  it { is_expected.to validate_numericality_of(:preferred_amount) }
 
   it "correctly calculates on a single line item object" do
     allow(calculator).to receive_messages(calculable: shipping_calculable)

spec/models/calculator/price_sack_spec.rb

@@ -12,20 +12,9 @@ describe Calculator::PriceSack do
   end
   let(:line_item) { build_stubbed(:line_item, price: price, quantity: 2) }
 
-  it do
-    should validate_numericality_of(:preferred_minimal_amount).
-      with_message("Invalid input. Please use only numbers. For example: 10, 5.5, -20")
-  end
-
-  it do
-    should validate_numericality_of(:preferred_normal_amount).
-      with_message("Invalid input. Please use only numbers. For example: 10, 5.5, -20")
-  end
-
-  it do
-    should validate_numericality_of(:preferred_discount_amount).
-      with_message("Invalid input. Please use only numbers. For example: 10, 5.5, -20")
-  end
+  it { is_expected.to validate_numericality_of(:preferred_minimal_amount) }
+  it { is_expected.to validate_numericality_of(:preferred_normal_amount) }
+  it { is_expected.to validate_numericality_of(:preferred_discount_amount) }
 
   context 'when the order amount is below preferred minimal' do
     let(:price) { 2 }