public void ToPostFormString()
        {
            var foo = new Foo {
                A = 1, B = "hello"
            };

            dynamic obj = new ExpandoObject();

            obj.A = foo.A;
            obj.B = foo.B;

            var formData = IDictionaryExtension.ToPostString(obj, null);

            Assert.Equal(formData, $"A={foo.A}&B={foo.B}");
        }
        public void ToPostJsonString()
        {
            var foo = new Foo {
                A = 1, B = "hello"
            };

            dynamic obj = new ExpandoObject();

            obj.A = foo.A;
            obj.B = foo.B;

            var json = IDictionaryExtension.ToPostString(obj, "application/json");

            Assert.Equal(json, JsonConvert.SerializeObject(foo));
        }