feat: added strong integer (#157)

* feat: Added strong integer type

* change test

* Update README.md

---------

Co-authored-by: Vladimir Dementyev <dementiev.vm@gmail.com>

README.md

@@ -714,7 +714,7 @@ CoolConfig.new.port == "443" #=> true
 
 **IMPORTANT**: Values provided explicitly (via attribute writers) are not coerced. Coercion is only happening during the load phase.
 
-The following types are supported out-of-the-box: `:string`, `:integer`, `:float`, `:date`, `:datetime`, `:uri`, `:boolean`.
+The following types are supported out-of-the-box: `:string`, `:integer`, `:integer!` (strict integer), `:float`, `:date`, `:datetime`, `:uri`, `:boolean`.
 
 You can use custom deserializers by passing a callable object instead of a type name:
 

lib/anyway/type_casting.rb

@@ -88,6 +88,10 @@ def dup
     obj.accept(:boolean) do
       _1.to_s.match?(/\A(true|t|yes|y|1)\z/i)
     end
+
+    obj.accept(:integer!) do
+      Integer(_1)
+    end
   end
 
   unless "".respond_to?(:safe_constantize)

spec/type_casting_spec.rb

@@ -8,6 +8,8 @@
   specify "default types" do
     expect(casting.deserialize("12", :string)).to eq("12")
     expect(casting.deserialize("12.3", :integer)).to eq(12)
+    expect(casting.deserialize("12", :integer!)).to eq(12)
+    expect { casting.deserialize("f", :integer!) }.to raise_error(ArgumentError, /invalid value for Integer()/)
     expect(casting.deserialize("12.3", :float)).to eq(12.3)
     expect(casting.deserialize("2020-08-30 17:01:03", :date)).to eq(Date.parse("2020-08-30"))
     expect(casting.deserialize(Time.local(2020, 8, 30, 11, 44, 22), :date)).to eq(Date.parse("2020-08-30"))