Stop using 'factory something() => null;' in most cases.

I did not change MockSdk, to avoid conflict with
https://dart-review.googlesource.com/c/sdk/+/135241

[email protected]

Bug: #40603
Change-Id: I9f0af20f5914b5ac1aefee02aa8052db269529b5
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/135532
Reviewed-by: Brian Wilkerson <[email protected]>
Commit-Queue: Konstantin Shcheglov <[email protected]>

Author: scheglov

pkg/analysis_server/test/analysis/notification_highlights2_test.dart

@@ -140,7 +140,8 @@ external main() {
   Future<void> test_BUILT_IN_factory() async {
     addTestFile('''
 class A {
-  factory A() => null;
+  A.named();
+  factory A() => A.named();
 }
 main() {
   var factory = 42;

pkg/analysis_server/test/analysis/notification_highlights_test.dart

@@ -140,7 +140,8 @@ external main() {
   Future<void> test_BUILT_IN_factory() async {
     addTestFile('''
 class A {
-  factory A() => null;
+  A.named();
+  factory A() => A();
 }
 main() {
   var factory = 42;

pkg/analysis_server/test/completion_test.dart

@@ -562,8 +562,8 @@ class FileMode {
   final int _mode;
 }
 class File {
-  factory File(String path) => null;
-  factory File.fromPath(Path path) => null;
+  File(String path);
+  File.fromPath(Path path);
 }
 f() => new Fil!1''', <String>[
       '1+File',

pkg/analysis_server/test/domain_completion_test.dart

@@ -55,7 +55,7 @@ class A {
 
   Future<void> test_ArgumentList_factory_named_param_label() async {
     addTestFile('main() { new A(^);}'
-        'class A { factory A({one, two}) => null; }');
+        'class A { factory A({one, two}) => throw 0; }');
     await getSuggestions();
     assertHasResult(CompletionSuggestionKind.NAMED_ARGUMENT, 'one: ',
         relevance: DART_RELEVANCE_NAMED_PARAMETER);

pkg/analysis_server/test/services/completion/dart/arglist_contributor_test.dart

@@ -606,7 +606,7 @@ foo({String children}) {}
   Future<void> test_ArgumentList_imported_factory_named_param() async {
     // ArgumentList  InstanceCreationExpression  ExpressionStatement
     addSource('/home/test/lib/a.dart',
-        'library libA; class A{factory A({int one}) => null;}');
+        'library libA; class A{factory A({int one}) => throw 0;}');
     addTestSource('import "a.dart"; main() { new A(^);}');
     await computeSuggestions();
     assertSuggestArgumentsAndTypes(namedArgumentsWithTypes: {'one': 'int'});

pkg/analysis_server/test/services/completion/dart/imported_reference_contributor_test.dart

@@ -2610,7 +2610,7 @@ main() {new ^ String x = "hello";}''');
 abstract class A {
   A();
   A.generative();
-  factory A.factory() => null;
+  factory A.factory() => A();
 }
 ''');
     addTestSource('''
@@ -3623,7 +3623,7 @@ class B extends A {
         var m;''');
     addTestSource('''
         part of libA;
-        class B { factory B.bar(int x) => null; }
+        class B { B.bar(int x); }
         main() {new ^}''');
 
     await computeSuggestions();

pkg/analysis_server/test/services/completion/dart/local_constructor_contributor_test.dart

@@ -2387,7 +2387,7 @@ main() {new ^ String x = "hello";}''');
 abstract class A {
   A();
   A.generative();
-  factory A.factory() => null;
+  factory A.factory() => A();
 }
 
 main() {
@@ -3285,7 +3285,7 @@ class A { }
 var m;''');
     addTestSource('''
 part of libA;
-class B { factory B.bar(int x) => null; }
+class B { B.bar(int x); }
 main() {new ^}''');
     await computeSuggestions();
 

pkg/analysis_server/test/services/completion/dart/local_library_contributor_test.dart

@@ -39,7 +39,7 @@ class LocalLibraryContributorTest extends DartCompletionContributorTest {
         var m;''');
     addTestSource('''
         part of libA;
-        class B { factory B.bar(int x) => null; }
+        class B { B.bar(int x); }
         main() {new ^}''');
     await computeSuggestions();
     expect(replacementOffset, completionOffset);
@@ -212,7 +212,7 @@ class LocalLibraryContributorTest extends DartCompletionContributorTest {
         int af() {return 0;}''');
     addTestSource('''
         part of libA;
-        class B { factory B.bar(int x) => null; }
+        class B { B.bar(int x); }
         main() {^}''');
     await computeSuggestions();
     expect(replacementOffset, completionOffset);

pkg/analysis_server/test/services/completion/dart/local_reference_contributor_test.dart

@@ -4121,7 +4121,7 @@ class A { }
 var m;''');
     addTestSource('''
 part of libA;
-class B { factory B.bar(int x) => null; }
+class B { B.bar(int x); }
 main() {new ^}''');
     await computeSuggestions();
 

pkg/analysis_server/test/services/completion/dart/type_member_contributor_test.dart

@@ -3238,7 +3238,7 @@ void main() {C.^ print("something");}''');
         var m;''');
     addTestSource('''
         part of libA;
-        class B { factory B.bar(int x) => null; }
+        class B { B.bar(int x); }
         main() {new ^}''');
     await computeSuggestions();
     expect(replacementOffset, completionOffset);

pkg/analysis_server/test/services/correction/sort_members_test.dart

@@ -248,15 +248,15 @@ class A {
   /// constructor generative unnamed
   A();
   /// constructor factory unnamed
-  factory A() => null;
+  factory A() => A();
   /// constructor generative public
   A.nnn();
   /// constructor factory public
-  factory A.ooo() => null;
+  factory A.ooo() => A();
   /// constructor generative private
   A._nnn();
   /// constructor factory private
-  factory A._ooo() => null;
+  factory A._ooo() => A();
 }
 ''');
     // validate change
@@ -281,15 +281,15 @@ class A {
   /// constructor generative unnamed
   A();
   /// constructor factory unnamed
-  factory A() => null;
+  factory A() => A();
   /// constructor generative public
   A.nnn();
   /// constructor factory public
-  factory A.ooo() => null;
+  factory A.ooo() => A();
   /// constructor generative private
   A._nnn();
   /// constructor factory private
-  factory A._ooo() => null;
+  factory A._ooo() => A();
   /// instance getter public
   int get nnn => null;
   /// instance setter public

pkg/analysis_server/test/src/services/correction/assist/convert_into_block_body_test.dart

@@ -73,13 +73,17 @@ main() {
   Future<void> test_constructor() async {
     await resolveTestUnit('''
 class A {
-  factory A() => null;
+  A.named();
+
+  factory A() => A.named();
 }
 ''');
     await assertHasAssistAt('A()', '''
 class A {
+  A.named();
+
   factory A() {
-    return null;
+    return A.named();
   }
 }
 ''');

pkg/analysis_server/test/src/services/correction/assist/convert_into_expression_body_test.dart

@@ -93,14 +93,18 @@ main() {
   Future<void> test_constructor() async {
     await resolveTestUnit('''
 class A {
+  A.named();
+
   factory A() {
-    return null;
+    return A.named();
   }
 }
 ''');
     await assertHasAssistAt('A()', '''
 class A {
-  factory A() => null;
+  A.named();
+
+  factory A() => A.named();
 }
 ''');
   }

pkg/analyzer/test/generated/compile_time_error_code.dart

@@ -921,7 +921,7 @@ class B extends A {
     await assertErrorsInCode(r'''
 class A {
   int x;
-  factory A(this.x) => null;
+  factory A(this.x) => throw 0;
 }
 ''', [
       error(CompileTimeErrorCode.FIELD_INITIALIZER_FACTORY_CONSTRUCTOR, 31, 6),

pkg/analyzer/test/generated/non_error_resolver_test.dart

@@ -2417,7 +2417,7 @@ class B extends Object with A {}
   test_mixinDeclaresConstructor_factory() async {
     await assertNoErrorsInCode(r'''
 class A {
-  factory A() => null;
+  factory A() => throw 0;
 }
 class B extends Object with A {}
 ''');

pkg/analyzer/test/generated/parser_test.dart

@@ -1418,7 +1418,7 @@ void Function<A>(core.List<core.int> x) m() => null;
   }
 
   void test_parseClassMember_redirectingFactory_expressionBody() {
-    createParser('factory C() => null;');
+    createParser('factory C() => throw 0;');
     var constructor = parser.parseClassMember('C') as ConstructorDeclaration;
     assertNoErrors();
     expect(constructor, isNotNull);
@@ -1494,7 +1494,7 @@ void Function<A>(core.List<core.int> x) m() => null;
   }
 
   void test_parseConstructor_factory_named() {
-    createParser('factory C.foo() => null;');
+    createParser('factory C.foo() => throw 0;');
     var constructor = parser.parseClassMember('C') as ConstructorDeclaration;
     assertNoErrors();
     expect(constructor, isNotNull);

pkg/analyzer/test/generated/simple_resolver_test.dart

@@ -853,7 +853,7 @@ class C = Object with A;''', [
   test_isValidMixin_factoryConstructor() async {
     await assertNoErrorsInCode(r'''
 class A {
-  factory A() => null;
+  factory A() => throw 0;
 }
 class C = Object with A;''');
     verifyTestResolved();

pkg/analyzer/test/src/dart/analysis/driver_resolution_test.dart

@@ -2018,8 +2018,8 @@ main() {
   test_instanceCreation_factory() async {
     String content = r'''
 class C {
-  factory C() => null;
-  factory C.named() => null;
+  factory C() => throw 0;
+  factory C.named() => throw 0;
 }
 var a = new C();
 var b = new C.named();
@@ -3153,7 +3153,7 @@ main() {
   test_invalid_instanceCreation_constOfNotConst_factory() async {
     addTestFile(r'''
 class C {
-  factory C(x) => null;
+  factory C(x) => throw 0;
 }
 
 var a = 0;

pkg/analyzer/test/src/diagnostics/invalid_factory_name_not_a_class_test.dart

@@ -19,7 +19,7 @@ class InvalidFactoryNameNotAClassTest extends DriverResolutionTest {
     await assertErrorsInCode(r'''
 int B;
 class A {
-  factory B() => null;
+  factory B() => throw 0;
 }
 ''', [
       error(CompileTimeErrorCode.INVALID_FACTORY_NAME_NOT_A_CLASS, 27, 1),
@@ -29,7 +29,7 @@ class A {
   test_notEnclosingClassName() async {
     await assertErrorsInCode(r'''
 class A {
-  factory B() => null;
+  factory B() => throw 0;
 }
 ''', [
       error(CompileTimeErrorCode.INVALID_FACTORY_NAME_NOT_A_CLASS, 20, 1),
@@ -39,7 +39,7 @@ class A {
   test_valid() async {
     await assertNoErrorsInCode(r'''
 class A {
-  factory A() => null;
+  factory A() => throw 0;
 }
 ''');
   }

pkg/analyzer/test/src/diagnostics/non_generative_constructor_test.dart

@@ -18,21 +18,21 @@ class NonGenerativeConstructorTest extends DriverResolutionTest {
   test_explicit() async {
     await assertErrorsInCode(r'''
 class A {
-  factory A.named() => null;
+  factory A.named() => throw 0;
 }
 class B extends A {
   B() : super.named();
 }
 ''', [
-      error(CompileTimeErrorCode.NON_GENERATIVE_CONSTRUCTOR, 69, 13),
+      error(CompileTimeErrorCode.NON_GENERATIVE_CONSTRUCTOR, 72, 13),
     ]);
   }
 
   test_generative() async {
     await assertNoErrorsInCode(r'''
 class A {
   A.named() {}
-  factory A() => null;
+  factory A() => throw 0;
 }
 class B extends A {
   B() : super.named();
@@ -43,25 +43,25 @@ class B extends A {
   test_implicit() async {
     await assertErrorsInCode(r'''
 class A {
-  factory A() => null;
+  factory A() => throw 0;
 }
 class B extends A {
   B();
 }
 ''', [
-      error(CompileTimeErrorCode.NON_GENERATIVE_CONSTRUCTOR, 57, 1),
+      error(CompileTimeErrorCode.NON_GENERATIVE_CONSTRUCTOR, 60, 1),
     ]);
   }
 
   test_implicit2() async {
     await assertErrorsInCode(r'''
 class A {
-  factory A() => null;
+  factory A() => throw 0;
 }
 class B extends A {
 }
 ''', [
-      error(CompileTimeErrorCode.NON_GENERATIVE_CONSTRUCTOR, 41, 1),
+      error(CompileTimeErrorCode.NON_GENERATIVE_CONSTRUCTOR, 44, 1),
     ]);
   }
 }

pkg/analyzer/test/src/diagnostics/recursive_factory_redirect_test.dart

@@ -134,7 +134,7 @@ class B implements A {
   factory B() = C;
 }
 class C implements B {
-  factory C() => null;
+  factory C() => throw 0;
 }
 ''');
   }

pkg/analyzer/test/src/diagnostics/redirect_generative_to_non_generative_constructor_test.dart

@@ -20,7 +20,7 @@ class RedirectGenerativeToNonGenerativeConstructorTest
     await assertErrorsInCode(r'''
 class A {
   A() : this.x();
-  factory A.x() => null;
+  factory A.x() => throw 0;
 }
 ''', [
       error(

pkg/analyzer/test/src/diagnostics/unused_element_test.dart

@@ -228,7 +228,7 @@ void f(d) {
   test_factoryConstructor_notUsed_multiple() async {
     await assertErrorsInCode(r'''
 class A {
-  factory A._factory() => null;
+  factory A._factory() => A();
   A();
 }
 ''', [
@@ -239,7 +239,7 @@ class A {
   test_factoryConstructor_notUsed_single() async {
     await assertNoErrorsInCode(r'''
 class A {
-  factory A._factory() => null;
+  factory A._factory() => throw 0;
 }
 ''');
   }

pkg/analyzer/test/src/fasta/ast_builder_test.dart

@@ -19,7 +19,7 @@ class AstBuilderTest extends FastaParserTestCase {
   void test_constructor_factory_misnamed() {
     CompilationUnit unit = parseCompilationUnit('''
 class A {
-  factory B() => null;
+  factory B() => throw 0;
 }
 ''');
     expect(unit, isNotNull);