public void LogsNullError()
        {
            Log4NetTracingInterceptor logger = new Log4NetTracingInterceptor("app.config");
            string invocationId = null;
            string expected     = string.Format("ERROR - invocationId: \r\n", invocationId, null);

            logger.TraceError(invocationId, null);
            string actual = File.ReadAllText(logFileName);

            Assert.Equal(expected, actual);
        }
        public void LogsError()
        {
            Log4NetTracingInterceptor logger = new Log4NetTracingInterceptor("app.config");
            string invocationId = "12345";
            var    exception    = new HttpOperationException <string>("I'm a cloud exception!");
            string expected     = string.Format("ERROR - invocationId: {0}\r\n{1}\r\n", invocationId, exception.ToString());

            logger.TraceError(invocationId, exception);
            string actual = File.ReadAllText(logFileName);

            Assert.Equal(expected, actual);
        }