Simplify configs for numeric field types

Addresses issues raised by CodeClimate in https://codeclimate.com/github/sferik/rails_admin/pull/3378 and further consolidates a shared base field config for numeric types

lib/rails_admin/config/fields/types/decimal.rb

@@ -1,17 +1,13 @@
-require 'rails_admin/config/fields/base'
+require 'rails_admin/config/fields/types/numeric'
 
 module RailsAdmin
   module Config
     module Fields
       module Types
-        class Decimal < RailsAdmin::Config::Fields::Base
+        class Decimal < RailsAdmin::Config::Fields::Types::Numeric
           # Register field type for the type loader
           RailsAdmin::Config::Fields::Types.register(self)
 
-          register_instance_option :view_helper do
-            :number_field
-          end
-
           register_instance_option :html_attributes do
             {
               required: required?,

lib/rails_admin/config/fields/types/float.rb

@@ -1,17 +1,13 @@
-require 'rails_admin/config/fields/base'
+require 'rails_admin/config/fields/types/numeric'
 
 module RailsAdmin
   module Config
     module Fields
       module Types
-        class Float < RailsAdmin::Config::Fields::Base
+        class Float < RailsAdmin::Config::Fields::Types::Numeric
           # Register field type for the type loader
           RailsAdmin::Config::Fields::Types.register(self)
 
-          register_instance_option :view_helper do
-            :number_field
-          end
-
           register_instance_option :html_attributes do
             {
               required: required?,

lib/rails_admin/config/fields/types/integer.rb

@@ -1,17 +1,13 @@
-require 'rails_admin/config/fields/base'
+require 'rails_admin/config/fields/types/numeric'
 
 module RailsAdmin
   module Config
     module Fields
       module Types
-        class Integer < RailsAdmin::Config::Fields::Base
+        class Integer < RailsAdmin::Config::Fields::Types::Numeric
           # Register field type for the type loader
           RailsAdmin::Config::Fields::Types.register(self)
 
-          register_instance_option :view_helper do
-            :number_field
-          end
-
           register_instance_option :sort_reverse? do
             serial?
           end

lib/rails_admin/config/fields/types/numeric.rb

@@ -0,0 +1,18 @@
+require 'rails_admin/config/fields/base'
+
+module RailsAdmin
+  module Config
+    module Fields
+      module Types
+        class Numeric < RailsAdmin::Config::Fields::Base
+          # Register field type for the type loader
+          RailsAdmin::Config::Fields::Types.register(self)
+
+          register_instance_option :view_helper do
+            :number_field
+          end
+        end
+      end
+    end
+  end
+end

spec/rails_admin/config/fields/types/numeric_spec.rb

@@ -0,0 +1,17 @@
+require 'spec_helper'
+
+RSpec.describe RailsAdmin::Config::Fields::Types::Numeric do
+  it_behaves_like 'a generic field type', :integer_field, :integer
+
+  subject do
+    RailsAdmin.config('FieldTest').fields.detect do |f|
+      f.name == :integer_field
+    end.with(object: FieldTest.new)
+  end
+
+  describe '#view_helper' do
+    it "uses the 'number' type input tag" do
+      expect(subject.view_helper).to eq(:number_field)
+    end
+  end
+end