Validation of `@required` params (#26182).

pkg/analyzer/test/generated/hint_code_test.dart

 // Copyright (c) 2016, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 library analyzer.test.generated.hint_code_test;
 
 import 'package:analyzer/src/generated/engine.dart';
 import 'package:analyzer/src/generated/error.dart';
 import 'package:analyzer/src/generated/source_io.dart';
 import 'package:unittest/unittest.dart';
@@ skipping 89 matching lines @@
   void reset() {
     analysisContext2 = AnalysisContextFactory.contextWithCoreAndPackages({
       'package:meta/meta.dart': r'''
 library meta;
 
 const _Factory factory = const _Factory();
 const _Literal literal = const _Literal();
 const _MustCallSuper mustCallSuper = const _MustCallSuper();
 const _Override override = const _Override();
 const _Protected protected = const _Protected();
-const _Required required = const _Required();
+const Required required = const Required();
+class Required {
+  final String reason;
+  const Required([this.reason]);
+}
 
 class _Factory {
   const _Factory();
 }
 class _Literal {
   const _Literal();
 }
 class _MustCallSuper {
   const _MustCallSuper();
 }
@@ skipping 1395 matching lines @@
 }
 class B extends A {
   @override
   set m(int x) {}
 }''');
     computeLibrarySourceErrors(source);
     assertErrors(source, [HintCode.OVERRIDE_ON_NON_OVERRIDING_SETTER]);
     verify([source]);
   }
 
+  void test_required_constructor_param() {
+    Source source = addSource(r'''
+import 'package:meta/meta.dart';
+
+class C {
+  C({@Required('must specify an `a`') int a}) {}
+}
+
+main() {
+  new C();
+}
+''');
+    computeLibrarySourceErrors(source);
+    assertErrors(source, [HintCode.MISSING_REQUIRED_PARAM]);
+    verify([source]);
+  }
+
+  void test_required_constructor_param_no_reason() {
+    Source source = addSource(r'''
+import 'package:meta/meta.dart';
+
+class C {
+  C({@required int a}) {}
+}
+
+main() {
+  new C();
+}
+''');
+    computeLibrarySourceErrors(source);
+    assertErrors(source, [HintCode.MISSING_REQUIRED_PARAM]);
+    verify([source]);
+  }
+
+  void test_required_constructor_param_null_reason() {
+    Source source = addSource(r'''
+import 'package:meta/meta.dart';
+
+class C {
+  C({@Required(null) int a}) {}
+}
+
+main() {
+  new C();
+}
+''');
+    computeLibrarySourceErrors(source);
+    assertErrors(source, [HintCode.MISSING_REQUIRED_PARAM]);
+    verify([source]);
+  }
+
+  void test_required_constructor_param_OK() {
+    Source source = addSource(r'''
+import 'package:meta/meta.dart';
+
+class C {
+  C({@required int a}) {}
+}
+
+main() {
+  new C(a: 2);
+}
+''');
+    computeLibrarySourceErrors(source);
+    assertNoErrors(source);
+    verify([source]);
+  }
+
+  void test_required_function_param() {
+    Source source = addSource(r'''
+import 'package:meta/meta.dart';
+
+void f({@Required('must specify an `a`') int a}) {}
+
+main() {
+  f();
+}
+''');
+    computeLibrarySourceErrors(source);
+    assertErrors(source, [HintCode.MISSING_REQUIRED_PARAM]);
+    verify([source]);
+  }
+
+  void test_required_method_param() {
+    Source source = addSource(r'''
+import 'package:meta/meta.dart';
+class A {
+  void m({@Required('must specify an `a`') int a}) {}
+}
+f() {
+  new A().m();
+}
+''');
+    computeLibrarySourceErrors(source);
+    assertErrors(source, [HintCode.MISSING_REQUIRED_PARAM]);
+    verify([source]);
+  }
+
   void test_typeCheck_type_is_Null() {
     Source source = addSource(r'''
 m(i) {
   bool b = i is Null;
 }''');
     computeLibrarySourceErrors(source);
     assertErrors(source, [HintCode.TYPE_CHECK_IS_NULL]);
     verify([source]);
   }
 
@@ skipping 1461 matching lines @@
   n() {
     var a = m(), b = m();
   }
 }''');
     computeLibrarySourceErrors(source);
     assertErrors(
         source, [HintCode.USE_OF_VOID_RESULT, HintCode.USE_OF_VOID_RESULT]);
     verify([source]);
   }
 }