Update with review feedback from srawlins

FAQ.md

@@ -207,6 +207,12 @@ Also, you can also check out the example configuration in the Mockito repository
 
 ## How do I mock a `sealed` class?
 
+`sealed` clases cannot be `extend`ed nor `implement`ed (outside of their Dart
+library) and therefore cannot be mocked.
+
+
+## How do I mock a class that requires instances of a `sealed` class?
+
 Suppose that you have code such as:
 
 ```dart
@@ -223,20 +229,21 @@ class Foo {
 }
 ```
 
-and now you want to mock `Foo`. The generated implementation for `MockFoo`
-needs to return *something* if `someMethod` is called. It can't return `null`
-since its return type is non-nullable. It can't construct a `Bar` on its own
-without understanding the semantics of `Bar`'s constructors. That is, which
-`Bar` constructor should be called and with what arguments? To avoid this,
-Mockito instead generates its own, fake implementation of `Bar` that it does
-know how to construct, something like:
+and now you want to mock `Foo`. A mock implementation of `Foo`, generated by
+`@GenerateNiceMocks([MockSpec<Foo>()])`, needs to return *something* if
+`someMethod` is called. It can't return `null` since its return type is
+non-nullable. It can't construct a `Bar` on its own without understanding the
+semantics of `Bar`'s constructors. That is, which `Bar` constructor should be
+called and with what arguments? To avoid this, Mockito instead generates its
+own, fake implementation of `Bar` that it does know how to construct, something
+`like:
 
 ```dart
 class _FakeBar extends Fake implements Bar {}
 ```
 
-And then the generated implementation of `MockFoo` can have its `someMethod`
-override return a `_FakeBar` instance.
+And then `MockFoo` can have its `someMethod` override return a `_FakeBar`
+instance.
 
 However, if `Bar` is `sealed` (or is marked with `base` or `final`), then it
 cannot be `implemented` in generated code. Therefore Mockito can't generate a

lib/src/dummies.dart

@@ -95,8 +95,9 @@ provide dummy values for some types, even if they plan to explicitly stub all
 the called methods. Call either `provideDummy` or `provideDummyBuilder` to
 provide Mockito with a dummy value.
 
-For more details, see:
-<https://github.com/dart-lang/mockito/blob/master/FAQ.md#how-do-i-mock-a-sealed-class>
+For more details, see the questions regarding `sealed` classes in the FAQ:
+
+<https://github.com/dart-lang/mockito/blob/master/FAQ.md>
 ''';
 }
 
@@ -168,8 +169,10 @@ void provideDummyBuilder<T>(DummyBuilder<T> dummyBuilder) =>
 /// Provide a dummy value for `T` to be used both while adding expectations
 /// and as a default value for unstubbed methods, if using a nice mock.
 ///
-/// For details and for example usage, see:
-/// https://github.com/dart-lang/mockito/blob/master/FAQ.md#how-do-i-mock-a-sealed-class
+/// For details and for example usage, see the questions regarding `sealed`
+/// classes in the [FAQ].
+///
+/// [FAQ]: https://github.com/dart-lang/mockito/blob/master/FAQ.md
 void provideDummy<T>(T dummy) =>
     provideDummyBuilder((parent, invocation) => dummy);