public static HttpCallAssertion WithExactBody(this HttpCallAssertion assert, string body)
 {
     return(assert.With(fc =>
     {
         fc.RequestBody.Should().Be(body);
         return true;
     }));
 }
 public static HttpCallAssertion WithJsonPropertyMatching(this HttpCallAssertion a, Func <dynamic, string> propertyPicker, string regex) =>
 a.With(r => propertyPicker.Invoke(JObject.Parse(r.RequestBody)).Matches(new Regex(regex)));
 public static HttpCallAssertion WithJsonProperty <TProperty>(this HttpCallAssertion a, Func <dynamic, TProperty> propertyPicker, TProperty expected)
     where TProperty : IEquatable <TProperty> => a.With(r => ((TProperty)propertyPicker.Invoke(JObject.Parse(r.RequestBody))).Equals(expected));