feat: Pass additional parameters to auhtorization url (#447)

lib/googleauth/user_authorizer.rb

@@ -80,14 +80,17 @@ def initialize client_id, scope, token_store, callback_uri = nil
       # @param [String, Array<String>] scope
       #  Authorization scope to request. Overrides the instance scopes if not
       #  nil.
+      # @param [Hash] additional_parameters
+      #  Additional query parameters to be added to the authorization URL.
       # @return [String]
       #  Authorization url
       def get_authorization_url options = {}
         scope = options[:scope] || @scope
         credentials = UserRefreshCredentials.new(
           client_id:     @client_id.id,
           client_secret: @client_id.secret,
-          scope:         scope
+          scope:         scope,
+          additional_parameters: options[:additional_parameters]
         )
         redirect_uri = redirect_uri_for options[:base_url]
         url = credentials.authorization_uri(access_type:            "offline",
@@ -144,6 +147,9 @@ def get_credentials user_id, scope = nil
       #  Absolute URL to resolve the configured callback uri against.
       #  Required if the configured
       #  callback uri is a relative.
+      # @param [Hash] additional_parameters
+      #  Additional parameters to be added to the post body of token
+      #  endpoint request.
       # @return [Google::Auth::UserRefreshCredentials]
       #  Credentials if exchange is successful
       def get_credentials_from_code options = {}
@@ -152,10 +158,11 @@ def get_credentials_from_code options = {}
         scope = options[:scope] || @scope
         base_url = options[:base_url]
         credentials = UserRefreshCredentials.new(
-          client_id:     @client_id.id,
-          client_secret: @client_id.secret,
-          redirect_uri:  redirect_uri_for(base_url),
-          scope:         scope
+          client_id:             @client_id.id,
+          client_secret:         @client_id.secret,
+          redirect_uri:          redirect_uri_for(base_url),
+          scope:                 scope,
+          additional_parameters: options[:additional_parameters]
         )
         credentials.code = code
         credentials.fetch_access_token!({})

spec/googleauth/user_authorizer_spec.rb

@@ -29,6 +29,9 @@
   let(:scope) { %w[email profile] }
   let(:token_store) { DummyTokenStore.new }
   let(:callback_uri) { "https://www.example.com/oauth/callback" }
+  let(:additional_parameters) do
+    { "param1": "value1", "param2": "value2" }
+  end
   let :authorizer do
     Google::Auth::UserAuthorizer.new(client_id,
                                      scope,
@@ -139,6 +142,19 @@
     end
   end
 
+  context "when generating authorization URLs with additional parameters" do
+    let(:uri) { authorizer.get_authorization_url additional_parameters: additional_parameters }
+
+    it_behaves_like "valid authorization url"
+
+    it "includes the additional parameters" do
+      expect(URI(uri).query).to match(/param1/)
+      expect(URI(uri).query).to match(/value1/)
+      expect(URI(uri).query).to match(/param2/)
+      expect(URI(uri).query).to match(/value2/)
+    end
+  end
+
   context "when retrieving tokens" do
     let :token_json do
       MultiJson.dump(