Header: http.Header{
					"Authorization": []string{"invalid-token"},
				},
			},
			expectedErr: errAuthentication,
		},
	}

	for i, testCase := range testCases {
		_, _, _, gotErr := metricsRequestAuthenticate(testCase.req)
		if testCase.expectedErr != gotErr {
			t.Errorf("Test %d, expected err %s, got %s", i+1, testCase.expectedErr, gotErr)
		}
	}
}

func BenchmarkParseJWTStandardClaims(b *testing.B) {

}

// Check if the request is authenticated.
// Returns nil if the request is authenticated. errNoAuthToken if token missing.
// Returns errAuthentication for all other errors.
func metricsRequestAuthenticate(req *http.Request) (*xjwt.MapClaims, []string, bool, error) {
	token, err := jwtreq.AuthorizationHeaderExtractor.ExtractToken(req)
	if err != nil {
		if err == jwtreq.ErrNoTokenInRequest {

	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		tc, ok := r.Context().Value(mcontext.ContextTraceKey).(*mcontext.TraceCtxt)

		claims, groups, owner, authErr := metricsRequestAuthenticate(r)
		if authErr != nil || (claims != nil && !claims.VerifyIssuer("prometheus", true)) {
			if ok {
				tc.FuncName = "handler.MetricsAuth"
				tc.ResponseRecorder.LogErrBody = true
			}