Allow to use Proc for generation of state

lib/omniauth/strategies/oauth2.rb

@@ -24,7 +24,7 @@ def self.inherited(subclass)
       option :client_secret, nil
       option :client_options, {}
       option :authorize_params, {}
-      option :authorize_options, [:scope]
+      option :authorize_options, [:scope, :state]
       option :token_params, {}
       option :token_options, []
       option :auth_token_params, {}
@@ -100,7 +100,11 @@ def deep_symbolize(options)
       def options_for(option)
         hash = {}
         options.send(:"#{option}_options").select { |key| options[key] }.each do |key|
-          hash[key.to_sym] = options[key]
+          hash[key.to_sym] = if options[key].respond_to?(:call)
+            options[key].call(env)
+          else
+            options[key]
+          end
         end
         hash
       end

spec/omniauth/strategies/oauth2_spec.rb

@@ -52,13 +52,20 @@ def app
       instance = subject.new("abc", "def", :authorize_options => [:scope, :foo, :state], :scope => "bar", :foo => "baz")
       expect(instance.authorize_params["scope"]).to eq("bar")
       expect(instance.authorize_params["foo"]).to eq("baz")
+      expect(instance.authorize_params["state"]).not_to be_empty
     end
 
     it "includes random state in the authorize params" do
       instance = subject.new("abc", "def")
       expect(instance.authorize_params.keys).to eq(["state"])
       expect(instance.session["omniauth.state"]).not_to be_empty
     end
+
+    it "includes custom state in the authorize params" do
+      instance = subject.new("abc", "def", state: Proc.new { "qux" } )
+      expect(instance.authorize_params.keys).to eq(["state"])
+      expect(instance.session["omniauth.state"]).to eq("qux")
+    end
   end
 
   describe "#token_params" do