Document breaking changes coming in 11.0

This issue tracks breaking changes coming in 11.0 that will need to be documented:

Supported platform changes

• Removal of netcore2.1 (MS official support ends 21 August 2021)

cascade mode changes

• #1822

Public API

• Asynchronous validators will now throw an exception when invoked synchronously, rather than silently running synchronously.
• OnFailure/OnAnyFailure removed
• Remove backwards compatibility property validator layer

Test Helper

• Remove deprecated test helper methods

Internal API

• IValidationRule<T,TProperty>.CurrentValidator has been removed (use the Current property instead)
• IValidationRule<T,TProperty>.Current now returns an IRuleComponent<T,TProperty> interface instead of RuleComponent<T,TProperty> (necessary to support variance)
• IValidationRule<T,TProperty>.MessageBuilder’s argument is now an IMessageBuilderContext<T,TProperty> interface instead of MessageBuilderContext<T,TProperty> class (necessary to support variance)
• IValidationRule<T,TProperty>.MessageBuilder is now set-only, and has no getter exposed (needed to support variance), meaning you can only have one message builder per rule chain.
• IRuleComponent<T,TProperty>.CustomStateProvider is now set-only to support variance
• IRuleComponent<T,TProperty>.SeverityProvider is now set-only to support variance
• GetErrorMessage is no longer exposed on IRuleComponent<T,TProperty>
• Remove deprecated Options property from RuleComponent
• MemberAccessor removed

Aspnet integration

• Remove deprecated RunDefaultMvcValidationAfterFluentValidationExecutes

[JeremySkinner]

I think you’ll also need to bring across the MemberAccessor class (or at least, the parts of it that dynamically build property setters)

[ronaldkroon]

Hi, Why are you deprecating this way of writing validation? This

  validator.ShouldNotHaveValidationErrorFor(x => x.Forename, "test");

looks so much better than

  var person = new Person {Forename = "test"};
  validator.TestValidate(person).ShouldNotHaveValidationErrorFor(x => x.Forename);

Plus it allowed us to write extensions methods to test multiple values at once like e.g.:

  public static void ShouldAllowAZ09ValuesOnly<TMessage>(this IValidator<TMessage> validator, 
    Expression<Func<TMessage, string>> expression)
    where TMessage : class, new()
  {
    foreach (var value in new[] { "A", "ABC", "A0", "0", "123" })
    {
      validator.ShouldNotHaveValidationErrorFor(expression, value);
    }
    foreach (var value in new[] { "a", "A B", "A-B" })
    {
      validator.ShouldHaveValidationErrorFor(expression, value);
    }
  }