Fix transform with default value (#93)

Fixes #92

---------

Co-authored-by: LiuChun <liuchun@gfttek.com>

Author: 1075461847

lib/rails_param/param_evaluator.rb

@@ -36,7 +36,7 @@ def param!(name, type, options = {}, &block)
       recurse_on_parameter(parameter, &block) if block_given?
 
       # apply transformation
-      parameter.transform if params.include?(name) && options[:transform]
+      parameter.transform if options[:transform]
 
       # validate
       validate!(parameter)

spec/rails_param/param_spec.rb

@@ -32,6 +32,12 @@ def params;
           controller.param! :word, String, transform: :upcase
           expect(controller.params["word"]).to eql("FOO")
         end
+
+        it "transforms default value" do
+          allow(controller).to receive(:params).and_return({})
+          controller.param! :word, String, default: "foo", transform: :upcase
+          expect(controller.params["word"]).to eql("FOO")
+        end
       end
 
       context "with a block" do
@@ -41,6 +47,12 @@ def params;
           expect(controller.params["word"]).to eql("foo")
         end
 
+        it "transforms default value" do
+          allow(controller).to receive(:params).and_return({})
+          controller.param! :word, String, default: "foo", transform: lambda { |n| n.upcase }
+          expect(controller.params["word"]).to eql("FOO")
+        end
+
         it "transforms falsey value" do
           allow(controller).to receive(:params).and_return({ "foo" => "0" })
           controller.param! :foo, :boolean, transform: lambda { |n| n ? "bar" : "no bar" }
@@ -54,6 +66,13 @@ def params;
           expect { controller.param! :foo, String, required: true, transform: :upcase }.to raise_error(RailsParam::InvalidParameterError, "Parameter foo is required")
         end
       end
+
+      context "when param is optional & not present" do
+        it "doesn't transform the value" do
+          allow(controller).to receive(:params).and_return({ })
+          expect { controller.param! :foo, String, transform: :upcase }.not_to raise_error
+        end
+      end
     end
 
     describe "default" do