public void AddCustomField() { var tId = Guid.NewGuid().ToString(); var ctx = new CorrelationContext(tId); Assert.Throws <ArgumentException>(() => ctx.Add("correlationId", "id")); Assert.Throws <ArgumentException>(() => ctx.Add("requestId", "id")); ctx.Add("custom", 123); Assert.Equal(123, ctx["custom"]); Assert.Equal(3, ctx.Count); }