Enforce use_key_in_widget_constructors and file_names lints (#913)

* Start enforcing use_key_in_widget_constructors and file_names lints

* dart format

* analysis fixes

* analysis fixes, pt2

* analysis fixes, part 3

* Revert platform_design (test failure)

* More reverts

* Notate why we aren't enforcing a lint

provider_shopper/analysis_options.yaml

@@ -17,4 +17,3 @@ linter:
     test_types_in_equals: true
     throw_in_finally: true
     unnecessary_statements: true
-    use_key_in_widget_constructors: false

provider_shopper/lib/main.dart

@@ -12,10 +12,12 @@ import 'package:provider_shopper/screens/catalog.dart';
 import 'package:provider_shopper/screens/login.dart';
 
 void main() {
-  runApp(MyApp());
+  runApp(const MyApp());
 }
 
 class MyApp extends StatelessWidget {
+  const MyApp({Key? key}) : super(key: key);
+
   @override
   Widget build(BuildContext context) {
     // Using MultiProvider is convenient when providing multiple objects.
@@ -41,9 +43,9 @@ class MyApp extends StatelessWidget {
         theme: appTheme,
         initialRoute: '/',
         routes: {
-          '/': (context) => MyLogin(),
-          '/catalog': (context) => MyCatalog(),
-          '/cart': (context) => MyCart(),
+          '/': (context) => const MyLogin(),
+          '/catalog': (context) => const MyCatalog(),
+          '/cart': (context) => const MyCart(),
         },
       ),
     );

provider_shopper/lib/screens/cart.dart

@@ -7,6 +7,8 @@ import 'package:provider/provider.dart';
 import 'package:provider_shopper/models/cart.dart';
 
 class MyCart extends StatelessWidget {
+  const MyCart({Key? key}) : super(key: key);
+
   @override
   Widget build(BuildContext context) {
     return Scaffold(

provider_shopper/lib/screens/catalog.dart

@@ -8,6 +8,8 @@ import 'package:provider_shopper/models/cart.dart';
 import 'package:provider_shopper/models/catalog.dart';
 
 class MyCatalog extends StatelessWidget {
+  const MyCatalog({Key? key}) : super(key: key);
+
   @override
   Widget build(BuildContext context) {
     return Scaffold(

provider_shopper/lib/screens/login.dart

@@ -5,6 +5,8 @@
 import 'package:flutter/material.dart';
 
 class MyLogin extends StatelessWidget {
+  const MyLogin({Key? key}) : super(key: key);
+
   @override
   Widget build(BuildContext context) {
     return Scaffold(

provider_shopper/test/cart_widget_test.dart

@@ -24,7 +24,7 @@ Widget createCartScreen() => MultiProvider(
           },
         ),
       ],
-      child: MaterialApp(
+      child: const MaterialApp(
         home: MyCart(),
       ),
     );

provider_shopper/test/catalog_widget_test.dart

@@ -21,7 +21,7 @@ Widget createCatalogScreen() => MultiProvider(
           },
         ),
       ],
-      child: MaterialApp(
+      child: const MaterialApp(
         home: MyCatalog(),
       ),
     );

provider_shopper/test/login_widget_test.dart

@@ -26,8 +26,8 @@ void main() {
       child: MaterialApp(
         initialRoute: '/',
         routes: {
-          '/': (context) => MyLogin(),
-          '/catalog': (context) => MyCatalog(),
+          '/': (context) => const MyLogin(),
+          '/catalog': (context) => const MyCatalog(),
         },
       ),
     ));

provider_shopper/test/widget_test.dart

@@ -9,7 +9,7 @@ import 'package:provider_shopper/main.dart';
 void main() {
   testWidgets('smoke test', (tester) async {
     // Build our app and trigger a frame.
-    await tester.pumpWidget(MyApp());
+    await tester.pumpWidget(const MyApp());
 
     // Navigating through login page.
     await tester.tap(find.text('ENTER'));