+    assert_equal "read_prefs", token["scope"]
+    test_token(token["access_token"], user, client)
+  end
+
+  def test_openid_connect
+    user = create(:user)
+    client = create(:oauth_application, :redirect_uri => "https://some.web.app.example.org/callback", :scopes => "openid read_prefs")
+    state = SecureRandom.urlsafe_base64(16)
+    verifier = SecureRandom.urlsafe_base64(48)
+    challenge = Base64.urlsafe_encode64(Digest::SHA256.digest(verifier), :padding => false)
+
+    authorize_client(user, client, :state => state, :code_challenge => challenge, :code_challenge_method => "S256", :scope => "openid read_prefs")
+    assert_response :redirect
+    code = validate_redirect(client, state)
+
+    token = request_token(client, code, verifier)
+
+    assert_equal "openid read_prefs", token["scope"]
+
+    access_token = token["access_token"]
+    assert_not_nil access_token
+
+    id_token = token["id_token"]
+    assert_not_nil id_token
+
+    data, _headers = JWT.decode id_token, nil, true, {
+      :algorithm => [Doorkeeper::OpenidConnect.signing_algorithm.to_s],
+      :verify_iss => true,
+      :iss => "#{Settings.server_protocol}://#{Settings.server_url}",
+      :verify_sub => true,
+      :sub => user.id,
+      :verify_aud => true,
+      :aud => client.uid
+    } do |headers, _payload|
+      kid = headers["kid"]
+      get oauth_discovery_keys_path
+      keys = response.parsed_body["keys"]
+      jwk = keys&.detect { |e| e["kid"] == kid }
+      jwk && JWT::JWK::RSA.import(jwk).public_key
+    end
+
+    assert_equal user.id.to_s, data["sub"]
+    assert_not data.key?("preferred_username")
+
+    get oauth_userinfo_path
+    assert_response :unauthorized
+
+    auth_header = bearer_authorization_header(access_token)
+    get oauth_userinfo_path, :headers => auth_header
+    assert_response :success
+
+    userinfo = response.parsed_body
+
+    assert_not_nil userinfo
+    assert_equal user.id.to_s, userinfo["sub"]
+    assert_equal user.display_name, userinfo["preferred_username"]
+  end
+
+  def test_openid_discovery
+    get oauth_discovery_provider_path
+    assert_response :success
+    openid_config = response.parsed_body
+
+    assert_equal "#{Settings.server_protocol}://#{Settings.server_url}", openid_config["issuer"]
+
+    assert_equal oauth_authorization_path, URI(openid_config["authorization_endpoint"]).path
+    assert_equal oauth_token_path, URI(openid_config["token_endpoint"]).path
+    assert_equal oauth_userinfo_path, URI(openid_config["userinfo_endpoint"]).path
+    assert_equal oauth_discovery_keys_path, URI(openid_config["jwks_uri"]).path
+  end
+
+  def test_openid_key
+    get oauth_discovery_keys_path
+    assert_response :success
+    key_info = response.parsed_body
+    assert key_info.key?("keys")
+    assert_equal 1, key_info["keys"].size
+    assert_equal Doorkeeper::OpenidConnect.signing_key.kid, key_info["keys"][0]["kid"]