Fix code generation error on nested generic bounded type arguments

CHANGELOG.md

@@ -1,3 +1,7 @@
+## 5.4.3
+
+* Fixed the bug with code generation on nested generic bounded type arguments. [#658](https://github.com/dart-lang/mockito/issues/658) 
+
 ## 5.4.2
 
 * Require code_builder 4.5.0.

lib/src/builder.dart

@@ -2051,7 +2051,20 @@ class _MockClassInfo {
 
   T _withTypeParameters<T>(Iterable<TypeParameterElement> typeParameters,
       T Function(Iterable<TypeReference>, Iterable<TypeReference>) body) {
-    final typeVars = {for (final t in typeParameters) t: _newTypeVar(t)};
+    final Map<TypeParameterElement, String> typeVars = {};
+    for (final t in typeParameters) {
+      final typeVar = _newTypeVar(t);
+      typeVars[t] = typeVar;
+      final bound = t.bound;
+      if (bound != null && bound is analyzer.InterfaceType) {
+        for (final type in bound.typeArguments) {
+          final element = type.element;
+          if (element != null && element is TypeParameterElement) {
+            typeVars[element] = typeVar;
+          }
+        }
+      }
+    }
     _typeVariableScopes.add(typeVars);
     final typeRefsWithBounds = typeParameters.map(_typeParameterReference);
     final typeRefs =

pubspec.yaml

@@ -1,5 +1,5 @@
 name: mockito
-version: 5.4.2
+version: 5.4.3
 description: >-
   A mock framework inspired by Mockito with APIs for Fakes, Mocks,
   behavior verification, and stubbing.

test/builder/custom_mocks_test.dart

@@ -1843,6 +1843,32 @@ void main() {
     expect(mocksContent, contains('Iterable<X1> m1<X1>(X1 Function(X)? f)'));
     expect(mocksContent, contains('Iterable<X1?> m2<X1>(X1 Function(X)? f)'));
   });
+
+  test('We preserve nested generic bounded type arguments', () async {
+    final mocksContent = await buildWithNonNullable({
+      ...annotationsAsset,
+      'foo|lib/foo.dart': dedent(r'''
+            class Foo<T> {}
+            abstract class Bar<T> {
+              Iterable<X> m1<X extends Foo<X>>(X Function(T) f);
+            }
+            abstract class FooBar<X> extends Bar<X> {}
+        '''),
+      'foo|test/foo_test.dart': '''
+            import 'package:foo/foo.dart';
+            import 'package:mockito/annotations.dart';
+
+            @GenerateNiceMocks([
+              MockSpec<Foo>(), MockSpec<Bar>(), MockSpec<FooBar>()
+            ])
+            void main() {}
+          '''
+    });
+    expect(mocksContent, contains('class MockBar<T>'));
+    expect(mocksContent, contains('class MockFooBar<X>'));
+    expect(mocksContent,
+        contains('Iterable<X1> m1<X1 extends _i2.Foo<X1>>(X1 Function(X)? f)'));
+  });
 }
 
 TypeMatcher<List<int>> _containsAllOf(a, [b]) => decodedMatches(