Migrate flutter_localizations to null safety. (#68645)

Migrate flutter_localizations to null safety.

dev/bots/test.dart

@@ -704,7 +704,7 @@ Future<void> _runFrameworkTests() async {
     await _runFlutterTest(path.join(flutterRoot, 'packages', 'flutter_driver'), tableData: bigqueryApi?.tabledata, tests: <String>[path.join('test', 'src', 'real_tests')]);
     await _runFlutterTest(path.join(flutterRoot, 'packages', 'integration_test'), tableData: bigqueryApi?.tabledata);
     await _runFlutterTest(path.join(flutterRoot, 'packages', 'flutter_goldens'), tableData: bigqueryApi?.tabledata);
-    await _runFlutterTest(path.join(flutterRoot, 'packages', 'flutter_localizations'), tableData: bigqueryApi?.tabledata);
+    await _runFlutterTest(path.join(flutterRoot, 'packages', 'flutter_localizations'), tableData: bigqueryApi?.tabledata, options: soundNullSafetyOptions);
     await _runFlutterTest(path.join(flutterRoot, 'packages', 'flutter_test'), tableData: bigqueryApi?.tabledata, options: soundNullSafetyOptions);
     await _runFlutterTest(path.join(flutterRoot, 'packages', 'fuchsia_remote_debug_protocol'), tableData: bigqueryApi?.tabledata);
     await _runFlutterTest(path.join(flutterRoot, 'dev', 'integration_tests', 'non_nullable'), options: mixedModeNullSafetyOptions);

dev/tools/localization/bin/gen_localizations.dart

@@ -382,15 +382,20 @@ $factoryDeclaration
 ///
 /// Used by [generateGetter] below.
 String generateType(Map<String, dynamic> attributes) {
+  bool optional = false;
+  String type = 'String';
   if (attributes != null) {
+    optional = attributes.containsKey('optional');
     switch (attributes['x-flutter-type'] as String) {
       case 'icuShortTimePattern':
-        return 'TimeOfDayFormat';
+        type = 'TimeOfDayFormat';
+        break;
       case 'scriptCategory':
-        return 'ScriptCategory';
+        type = 'ScriptCategory';
+        break;
     }
   }
-  return 'String';
+  return type + (optional ? '?' : '');
 }
 
 /// Returns the appropriate name for getters with the given attributes.

dev/tools/localization/gen_cupertino_localizations.dart

@@ -16,7 +16,6 @@ HeaderGenerator generateCupertinoHeader = (String regenerateInstructions) {
 
 import 'dart:collection';
 
-import 'package:flutter/foundation.dart';
 import 'package:flutter/cupertino.dart';
 import 'package:intl/intl.dart' as intl;
 
@@ -40,14 +39,14 @@ ConstructorGenerator generateCupertinoConstructor = (LocaleInfo locale) {
   /// For details on the meaning of the arguments, see [GlobalCupertinoLocalizations].
   const CupertinoLocalization${locale.camelCase()}({
     String localeName = '$localeName',
-    @required intl.DateFormat fullYearFormat,
-    @required intl.DateFormat dayFormat,
-    @required intl.DateFormat mediumDateFormat,
-    @required intl.DateFormat singleDigitHourFormat,
-    @required intl.DateFormat singleDigitMinuteFormat,
-    @required intl.DateFormat doubleDigitMinuteFormat,
-    @required intl.DateFormat singleDigitSecondFormat,
-    @required intl.NumberFormat decimalFormat,
+    required intl.DateFormat fullYearFormat,
+    required intl.DateFormat dayFormat,
+    required intl.DateFormat mediumDateFormat,
+    required intl.DateFormat singleDigitHourFormat,
+    required intl.DateFormat singleDigitMinuteFormat,
+    required intl.DateFormat doubleDigitMinuteFormat,
+    required intl.DateFormat singleDigitSecondFormat,
+    required intl.NumberFormat decimalFormat,
   }) : super(
     localeName: localeName,
     fullYearFormat: fullYearFormat,
@@ -64,7 +63,7 @@ ConstructorGenerator generateCupertinoConstructor = (LocaleInfo locale) {
 const String cupertinoFactoryName = 'getCupertinoTranslation';
 
 const String cupertinoFactoryDeclaration = '''
-GlobalCupertinoLocalizations getCupertinoTranslation(
+GlobalCupertinoLocalizations? getCupertinoTranslation(
   Locale locale,
   intl.DateFormat fullYearFormat,
   intl.DateFormat dayFormat,

dev/tools/localization/gen_material_localizations.dart

@@ -16,7 +16,6 @@ HeaderGenerator generateMaterialHeader = (String regenerateInstructions) {
 
 import 'dart:collection';
 
-import 'package:flutter/foundation.dart';
 import 'package:flutter/material.dart';
 import 'package:intl/intl.dart' as intl;
 
@@ -40,15 +39,15 @@ ConstructorGenerator generateMaterialConstructor = (LocaleInfo locale) {
   /// For details on the meaning of the arguments, see [GlobalMaterialLocalizations].
   const MaterialLocalization${locale.camelCase()}({
     String localeName = '$localeName',
-    @required intl.DateFormat fullYearFormat,
-    @required intl.DateFormat compactDateFormat,
-    @required intl.DateFormat shortDateFormat,
-    @required intl.DateFormat mediumDateFormat,
-    @required intl.DateFormat longDateFormat,
-    @required intl.DateFormat yearMonthFormat,
-    @required intl.DateFormat shortMonthDayFormat,
-    @required intl.NumberFormat decimalFormat,
-    @required intl.NumberFormat twoDigitZeroPaddedFormat,
+    required intl.DateFormat fullYearFormat,
+    required intl.DateFormat compactDateFormat,
+    required intl.DateFormat shortDateFormat,
+    required intl.DateFormat mediumDateFormat,
+    required intl.DateFormat longDateFormat,
+    required intl.DateFormat yearMonthFormat,
+    required intl.DateFormat shortMonthDayFormat,
+    required intl.NumberFormat decimalFormat,
+    required intl.NumberFormat twoDigitZeroPaddedFormat,
   }) : super(
     localeName: localeName,
     fullYearFormat: fullYearFormat,
@@ -66,7 +65,7 @@ ConstructorGenerator generateMaterialConstructor = (LocaleInfo locale) {
 const String materialFactoryName = 'getMaterialTranslation';
 
 const String materialFactoryDeclaration = '''
-GlobalMaterialLocalizations getMaterialTranslation(
+GlobalMaterialLocalizations? getMaterialTranslation(
   Locale locale,
   intl.DateFormat fullYearFormat,
   intl.DateFormat compactDateFormat,

dev/tools/localization/localizations_validator.dart

@@ -67,8 +67,9 @@ void validateEnglishLocalizations(File file) {
       continue;
     }
 
+    final bool optional = atResource.containsKey('optional');
     final String description = atResource['description'] as String;
-    if (description == null)
+    if (description == null && !optional)
       errorMessages.writeln('No description specified for $atResourceId');
 
     final String plural = atResource['plural'] as String;
@@ -78,7 +79,7 @@ void validateEnglishLocalizations(File file) {
       if (!bundle.containsKey(resourceIdOther))
         errorMessages.writeln('Default plural resource $resourceIdOther undefined');
     } else {
-      if (!bundle.containsKey(resourceId))
+      if (!optional && !bundle.containsKey(resourceId))
         errorMessages.writeln('No matching $resourceId defined for $atResourceId');
     }
   }

packages/flutter/lib/src/cupertino/date_picker.dart

@@ -1763,9 +1763,10 @@ class _CupertinoTimerPickerState extends State<CupertinoTimerPicker> {
         });
       },
       children: List<Widget>.generate(24, (int index) {
+        final String label = localizations.timerPickerHourLabel(index) ?? '';
         final String semanticsLabel = textDirectionFactor == 1
-            ? localizations.timerPickerHour(index) + localizations.timerPickerHourLabel(index)
-            : localizations.timerPickerHourLabel(index) + localizations.timerPickerHour(index);
+            ? localizations.timerPickerHour(index) + label
+            : label + localizations.timerPickerHour(index);
 
         return Semantics(
           label: semanticsLabel,
@@ -1793,7 +1794,7 @@ class _CupertinoTimerPickerState extends State<CupertinoTimerPicker> {
           child: _buildHourPicker(additionalPadding, selectionOverlay),
         ),
         _buildLabel(
-          localizations.timerPickerHourLabel(lastSelectedHour ?? selectedHour!),
+          localizations.timerPickerHourLabel(lastSelectedHour ?? selectedHour!) ?? '',
           additionalPadding,
         ),
       ],
@@ -1826,10 +1827,10 @@ class _CupertinoTimerPickerState extends State<CupertinoTimerPicker> {
       },
       children: List<Widget>.generate(60 ~/ widget.minuteInterval, (int index) {
         final int minute = index * widget.minuteInterval;
-
+        final String label = localizations.timerPickerMinuteLabel(minute) ?? '';
         final String semanticsLabel = textDirectionFactor == 1
-            ? localizations.timerPickerMinute(minute) + localizations.timerPickerMinuteLabel(minute)
-            : localizations.timerPickerMinuteLabel(minute) + localizations.timerPickerMinute(minute);
+            ? localizations.timerPickerMinute(minute) + label
+            : label + localizations.timerPickerMinute(minute);
 
         return Semantics(
           label: semanticsLabel,
@@ -1857,7 +1858,7 @@ class _CupertinoTimerPickerState extends State<CupertinoTimerPicker> {
           child: _buildMinutePicker(additionalPadding, selectionOverlay),
         ),
         _buildLabel(
-          localizations.timerPickerMinuteLabel(lastSelectedMinute ?? selectedMinute),
+          localizations.timerPickerMinuteLabel(lastSelectedMinute ?? selectedMinute) ?? '',
           additionalPadding,
         ),
       ],
@@ -1890,10 +1891,10 @@ class _CupertinoTimerPickerState extends State<CupertinoTimerPicker> {
       },
       children: List<Widget>.generate(60 ~/ widget.secondInterval, (int index) {
         final int second = index * widget.secondInterval;
-
+        final String label = localizations.timerPickerSecondLabel(second) ?? '';
         final String semanticsLabel = textDirectionFactor == 1
-            ? localizations.timerPickerSecond(second) + localizations.timerPickerSecondLabel(second)
-            : localizations.timerPickerSecondLabel(second) + localizations.timerPickerSecond(second);
+            ? localizations.timerPickerSecond(second) + label
+            : label + localizations.timerPickerSecond(second);
 
         return Semantics(
           label: semanticsLabel,
@@ -1921,7 +1922,7 @@ class _CupertinoTimerPickerState extends State<CupertinoTimerPicker> {
           child: _buildSecondPicker(additionalPadding, selectionOverlay),
         ),
         _buildLabel(
-          localizations.timerPickerSecondLabel(lastSelectedSecond ?? selectedSecond!),
+          localizations.timerPickerSecondLabel(lastSelectedSecond ?? selectedSecond!) ?? '',
           additionalPadding,
         ),
       ],

packages/flutter/lib/src/cupertino/localizations.dart

@@ -108,7 +108,7 @@ abstract class CupertinoLocalizations {
 
   /// Semantics label for the given hour value in [CupertinoDatePicker].
   // The global version uses the translated string from the arb file.
-  String datePickerHourSemanticsLabel(int hour);
+  String? datePickerHourSemanticsLabel(int hour);
 
   /// Minute that is shown in [CupertinoDatePicker] spinner corresponding
   /// to the given minute value.
@@ -122,7 +122,7 @@ abstract class CupertinoLocalizations {
 
   /// Semantics label for the given minute value in [CupertinoDatePicker].
   // The global version uses the translated string from the arb file.
-  String datePickerMinuteSemanticsLabel(int minute);
+  String? datePickerMinuteSemanticsLabel(int minute);
 
   /// The order of the date elements that will be shown in [CupertinoDatePicker].
   // The global version uses the translated string from the arb file.
@@ -190,7 +190,7 @@ abstract class CupertinoLocalizations {
   /// [CupertinoTimerPicker] when selected hour value is `hour`.
   /// This function will deal with pluralization based on the `hour` parameter.
   // The global version uses the translated string from the arb file.
-  String timerPickerHourLabel(int hour);
+  String? timerPickerHourLabel(int hour);
 
   /// All possible hour labels that appears next to the hour picker in
   /// [CupertinoTimerPicker]
@@ -200,7 +200,7 @@ abstract class CupertinoLocalizations {
   /// [CupertinoTimerPicker] when selected minute value is `minute`.
   /// This function will deal with pluralization based on the `minute` parameter.
   // The global version uses the translated string from the arb file.
-  String timerPickerMinuteLabel(int minute);
+  String? timerPickerMinuteLabel(int minute);
 
   /// All possible minute labels that appears next to the minute picker in
   /// [CupertinoTimerPicker]
@@ -210,7 +210,7 @@ abstract class CupertinoLocalizations {
   /// [CupertinoTimerPicker] when selected minute value is `second`.
   /// This function will deal with pluralization based on the `second` parameter.
   // The global version uses the translated string from the arb file.
-  String timerPickerSecondLabel(int second);
+  String? timerPickerSecondLabel(int second);
 
   /// All possible second labels that appears next to the second picker in
   /// [CupertinoTimerPicker]

packages/flutter_localizations/analysis_options.yaml

+# Use the parent analysis options settings and enable null-experiment.
+
+include: ../analysis_options.yaml
+
+analyzer:
+  errors:
+    always_require_non_null_named_parameters: false # not needed with nnbd
+    type_init_formals: false # https://github.com/dart-lang/linter/issues/2192
+    unrelated_type_equality_checks: false # https://github.com/dart-lang/linter/issues/2196
+    void_checks: false # https://github.com/dart-lang/linter/issues/2185
+    unnecessary_null_comparison: false # Turned off until null-safe rollout is complete.

packages/flutter_localizations/lib/src/cupertino_localizations.dart

@@ -54,15 +54,15 @@ abstract class GlobalCupertinoLocalizations implements CupertinoLocalizations {
   /// The remaining '*Format' arguments uses the intl package to provide
   /// [DateFormat] configurations for the `localeName`.
   const GlobalCupertinoLocalizations({
-    @required String localeName,
-    @required intl.DateFormat fullYearFormat,
-    @required intl.DateFormat dayFormat,
-    @required intl.DateFormat mediumDateFormat,
-    @required intl.DateFormat singleDigitHourFormat,
-    @required intl.DateFormat singleDigitMinuteFormat,
-    @required intl.DateFormat doubleDigitMinuteFormat,
-    @required intl.DateFormat singleDigitSecondFormat,
-    @required intl.NumberFormat decimalFormat,
+    required String localeName,
+    required intl.DateFormat fullYearFormat,
+    required intl.DateFormat dayFormat,
+    required intl.DateFormat mediumDateFormat,
+    required intl.DateFormat singleDigitHourFormat,
+    required intl.DateFormat singleDigitMinuteFormat,
+    required intl.DateFormat doubleDigitMinuteFormat,
+    required intl.DateFormat singleDigitSecondFormat,
+    required intl.NumberFormat decimalFormat,
   }) : assert(localeName != null),
        _localeName = localeName,
        assert(fullYearFormat != null),
@@ -127,20 +127,20 @@ abstract class GlobalCupertinoLocalizations implements CupertinoLocalizations {
   }
 
   /// Subclasses should provide the optional zero pluralization of [datePickerHourSemanticsLabel] based on the ARB file.
-  @protected String get datePickerHourSemanticsLabelZero => null;
+  @protected String? get datePickerHourSemanticsLabelZero => null;
   /// Subclasses should provide the optional one pluralization of [datePickerHourSemanticsLabel] based on the ARB file.
-  @protected String get datePickerHourSemanticsLabelOne => null;
+  @protected String? get datePickerHourSemanticsLabelOne => null;
   /// Subclasses should provide the optional two pluralization of [datePickerHourSemanticsLabel] based on the ARB file.
-  @protected String get datePickerHourSemanticsLabelTwo => null;
+  @protected String? get datePickerHourSemanticsLabelTwo => null;
   /// Subclasses should provide the optional few pluralization of [datePickerHourSemanticsLabel] based on the ARB file.
-  @protected String get datePickerHourSemanticsLabelFew => null;
+  @protected String? get datePickerHourSemanticsLabelFew => null;
   /// Subclasses should provide the optional many pluralization of [datePickerHourSemanticsLabel] based on the ARB file.
-  @protected String get datePickerHourSemanticsLabelMany => null;
+  @protected String? get datePickerHourSemanticsLabelMany => null;
   /// Subclasses should provide the required other pluralization of [datePickerHourSemanticsLabel] based on the ARB file.
-  @protected String get datePickerHourSemanticsLabelOther;
+  @protected String? get datePickerHourSemanticsLabelOther;
 
   @override
-  String datePickerHourSemanticsLabel(int hour) {
+  String? datePickerHourSemanticsLabel(int hour) {
     return intl.Intl.pluralLogic(
       hour,
       zero: datePickerHourSemanticsLabelZero,
@@ -150,24 +150,24 @@ abstract class GlobalCupertinoLocalizations implements CupertinoLocalizations {
       many: datePickerHourSemanticsLabelMany,
       other: datePickerHourSemanticsLabelOther,
       locale: _localeName,
-    ).replaceFirst(r'$hour', _decimalFormat.format(hour));
+    )?.replaceFirst(r'$hour', _decimalFormat.format(hour));
   }
 
   /// Subclasses should provide the optional zero pluralization of [datePickerMinuteSemanticsLabel] based on the ARB file.
-  @protected String get datePickerMinuteSemanticsLabelZero => null;
+  @protected String? get datePickerMinuteSemanticsLabelZero => null;
   /// Subclasses should provide the optional one pluralization of [datePickerMinuteSemanticsLabel] based on the ARB file.
-  @protected String get datePickerMinuteSemanticsLabelOne => null;
+  @protected String? get datePickerMinuteSemanticsLabelOne => null;
   /// Subclasses should provide the optional two pluralization of [datePickerMinuteSemanticsLabel] based on the ARB file.
-  @protected String get datePickerMinuteSemanticsLabelTwo => null;
+  @protected String? get datePickerMinuteSemanticsLabelTwo => null;
   /// Subclasses should provide the optional few pluralization of [datePickerMinuteSemanticsLabel] based on the ARB file.
-  @protected String get datePickerMinuteSemanticsLabelFew => null;
+  @protected String? get datePickerMinuteSemanticsLabelFew => null;
   /// Subclasses should provide the optional many pluralization of [datePickerMinuteSemanticsLabel] based on the ARB file.
-  @protected String get datePickerMinuteSemanticsLabelMany => null;
+  @protected String? get datePickerMinuteSemanticsLabelMany => null;
   /// Subclasses should provide the required other pluralization of [datePickerMinuteSemanticsLabel] based on the ARB file.
-  @protected String get datePickerMinuteSemanticsLabelOther;
+  @protected String? get datePickerMinuteSemanticsLabelOther;
 
   @override
-  String datePickerMinuteSemanticsLabel(int minute) {
+  String? datePickerMinuteSemanticsLabel(int minute) {
     return intl.Intl.pluralLogic(
       minute,
       zero: datePickerMinuteSemanticsLabelZero,
@@ -177,7 +177,7 @@ abstract class GlobalCupertinoLocalizations implements CupertinoLocalizations {
       many: datePickerMinuteSemanticsLabelMany,
       other: datePickerMinuteSemanticsLabelOther,
       locale: _localeName,
-    ).replaceFirst(r'$minute', _decimalFormat.format(minute));
+    )?.replaceFirst(r'$minute', _decimalFormat.format(minute));
   }
 
   /// A string describing the [DatePickerDateOrder] enum value.
@@ -210,7 +210,7 @@ abstract class GlobalCupertinoLocalizations implements CupertinoLocalizations {
           "locale $_localeName.\nNon conforming string for $_localeName's "
           '.arb file',
         );
-        return null;
+        return DatePickerDateOrder.mdy;
     }
   }
 
@@ -244,7 +244,7 @@ abstract class GlobalCupertinoLocalizations implements CupertinoLocalizations {
           "for locale $_localeName.\nNon conforming string for $_localeName's "
           '.arb file',
         );
-        return null;
+        return DatePickerDateTimeOrder.date_time_dayPeriod;
     }
   }
 
@@ -254,7 +254,7 @@ abstract class GlobalCupertinoLocalizations implements CupertinoLocalizations {
   String get tabSemanticsLabelRaw;
 
   @override
-  String tabSemanticsLabel({ int tabIndex, int tabCount }) {
+  String tabSemanticsLabel({ required int tabIndex, required int tabCount }) {
     assert(tabIndex >= 1);
     assert(tabCount >= 1);
     final String template = tabSemanticsLabelRaw;
@@ -279,20 +279,20 @@ abstract class GlobalCupertinoLocalizations implements CupertinoLocalizations {
   }
 
   /// Subclasses should provide the optional zero pluralization of [timerPickerHourLabel] based on the ARB file.
-  @protected String get timerPickerHourLabelZero => null;
+  @protected String? get timerPickerHourLabelZero => null;
   /// Subclasses should provide the optional one pluralization of [timerPickerHourLabel] based on the ARB file.
-  @protected String get timerPickerHourLabelOne => null;
+  @protected String? get timerPickerHourLabelOne => null;
   /// Subclasses should provide the optional two pluralization of [timerPickerHourLabel] based on the ARB file.
-  @protected String get timerPickerHourLabelTwo => null;
+  @protected String? get timerPickerHourLabelTwo => null;
   /// Subclasses should provide the optional few pluralization of [timerPickerHourLabel] based on the ARB file.
-  @protected String get timerPickerHourLabelFew => null;
+  @protected String? get timerPickerHourLabelFew => null;
   /// Subclasses should provide the optional many pluralization of [timerPickerHourLabel] based on the ARB file.
-  @protected String get timerPickerHourLabelMany => null;
+  @protected String? get timerPickerHourLabelMany => null;
   /// Subclasses should provide the required other pluralization of [timerPickerHourLabel] based on the ARB file.
-  @protected String get timerPickerHourLabelOther;
+  @protected String? get timerPickerHourLabelOther;
 
   @override
-  String timerPickerHourLabel(int hour) {
+  String? timerPickerHourLabel(int hour) {
     return intl.Intl.pluralLogic(
       hour,
       zero: timerPickerHourLabelZero,
@@ -302,34 +302,34 @@ abstract class GlobalCupertinoLocalizations implements CupertinoLocalizations {
       many: timerPickerHourLabelMany,
       other: timerPickerHourLabelOther,
       locale: _localeName,
-    ).replaceFirst(r'$hour', _decimalFormat.format(hour));
+    )?.replaceFirst(r'$hour', _decimalFormat.format(hour));
   }
 
   @override
   List<String> get timerPickerHourLabels => <String>[
-    timerPickerHourLabelZero,
-    timerPickerHourLabelOne,
-    timerPickerHourLabelTwo,
-    timerPickerHourLabelFew,
-    timerPickerHourLabelMany,
-    timerPickerHourLabelOther,
+    if (timerPickerHourLabelZero != null) timerPickerHourLabelZero!,
+    if (timerPickerHourLabelOne != null) timerPickerHourLabelOne!,
+    if (timerPickerHourLabelTwo != null) timerPickerHourLabelTwo!,
+    if (timerPickerHourLabelFew != null) timerPickerHourLabelFew!,
+    if (timerPickerHourLabelMany != null) timerPickerHourLabelMany!,
+    if (timerPickerHourLabelOther != null) timerPickerHourLabelOther!,
   ];
 
   /// Subclasses should provide the optional zero pluralization of [timerPickerMinuteLabel] based on the ARB file.
-  @protected String get timerPickerMinuteLabelZero => null;
+  @protected String? get timerPickerMinuteLabelZero => null;
   /// Subclasses should provide the optional one pluralization of [timerPickerMinuteLabel] based on the ARB file.
-  @protected String get timerPickerMinuteLabelOne => null;
+  @protected String? get timerPickerMinuteLabelOne => null;
   /// Subclasses should provide the optional two pluralization of [timerPickerMinuteLabel] based on the ARB file.
-  @protected String get timerPickerMinuteLabelTwo => null;
+  @protected String? get timerPickerMinuteLabelTwo => null;
   /// Subclasses should provide the optional few pluralization of [timerPickerMinuteLabel] based on the ARB file.
-  @protected String get timerPickerMinuteLabelFew => null;
+  @protected String? get timerPickerMinuteLabelFew => null;
   /// Subclasses should provide the optional many pluralization of [timerPickerMinuteLabel] based on the ARB file.
-  @protected String get timerPickerMinuteLabelMany => null;
+  @protected String? get timerPickerMinuteLabelMany => null;
   /// Subclasses should provide the required other pluralization of [timerPickerMinuteLabel] based on the ARB file.
-  @protected String get timerPickerMinuteLabelOther;
+  @protected String? get timerPickerMinuteLabelOther;
 
   @override
-  String timerPickerMinuteLabel(int minute) {
+  String? timerPickerMinuteLabel(int minute) {
     return intl.Intl.pluralLogic(
       minute,
       zero: timerPickerMinuteLabelZero,
@@ -339,34 +339,34 @@ abstract class GlobalCupertinoLocalizations implements CupertinoLocalizations {
       many: timerPickerMinuteLabelMany,
       other: timerPickerMinuteLabelOther,
       locale: _localeName,
-    ).replaceFirst(r'$minute', _decimalFormat.format(minute));
+    )?.replaceFirst(r'$minute', _decimalFormat.format(minute));
   }
 
   @override
   List<String> get timerPickerMinuteLabels => <String>[
-    timerPickerMinuteLabelZero,
-    timerPickerMinuteLabelOne,
-    timerPickerMinuteLabelTwo,
-    timerPickerMinuteLabelFew,
-    timerPickerMinuteLabelMany,
-    timerPickerMinuteLabelOther,
+    if (timerPickerMinuteLabelZero != null) timerPickerMinuteLabelZero!,
+    if (timerPickerMinuteLabelOne != null) timerPickerMinuteLabelOne!,
+    if (timerPickerMinuteLabelTwo != null) timerPickerMinuteLabelTwo!,
+    if (timerPickerMinuteLabelFew != null) timerPickerMinuteLabelFew!,
+    if (timerPickerMinuteLabelMany != null) timerPickerMinuteLabelMany!,
+    if (timerPickerMinuteLabelOther != null) timerPickerMinuteLabelOther!,
   ];
 
   /// Subclasses should provide the optional zero pluralization of [timerPickerSecondLabel] based on the ARB file.
-  @protected String get timerPickerSecondLabelZero => null;
+  @protected String? get timerPickerSecondLabelZero => null;
   /// Subclasses should provide the optional one pluralization of [timerPickerSecondLabel] based on the ARB file.
-  @protected String get timerPickerSecondLabelOne => null;
+  @protected String? get timerPickerSecondLabelOne => null;
   /// Subclasses should provide the optional two pluralization of [timerPickerSecondLabel] based on the ARB file.
-  @protected String get timerPickerSecondLabelTwo => null;
+  @protected String? get timerPickerSecondLabelTwo => null;
   /// Subclasses should provide the optional few pluralization of [timerPickerSecondLabel] based on the ARB file.
-  @protected String get timerPickerSecondLabelFew => null;
+  @protected String? get timerPickerSecondLabelFew => null;
   /// Subclasses should provide the optional many pluralization of [timerPickerSecondLabel] based on the ARB file.
-  @protected String get timerPickerSecondLabelMany => null;
+  @protected String? get timerPickerSecondLabelMany => null;
   /// Subclasses should provide the required other pluralization of [timerPickerSecondLabel] based on the ARB file.
-  @protected String get timerPickerSecondLabelOther;
+  @protected String? get timerPickerSecondLabelOther;
 
   @override
-  String timerPickerSecondLabel(int second) {
+  String? timerPickerSecondLabel(int second) {
     return intl.Intl.pluralLogic(
       second,
       zero: timerPickerSecondLabelZero,
@@ -376,17 +376,17 @@ abstract class GlobalCupertinoLocalizations implements CupertinoLocalizations {
       many: timerPickerSecondLabelMany,
       other: timerPickerSecondLabelOther,
       locale: _localeName,
-    ).replaceFirst(r'$second', _decimalFormat.format(second));
+    )?.replaceFirst(r'$second', _decimalFormat.format(second));
   }
 
   @override
   List<String> get timerPickerSecondLabels => <String>[
-    timerPickerSecondLabelZero,
-    timerPickerSecondLabelOne,
-    timerPickerSecondLabelTwo,
-    timerPickerSecondLabelFew,
-    timerPickerSecondLabelMany,
-    timerPickerSecondLabelOther,
+    if (timerPickerSecondLabelZero != null) timerPickerSecondLabelZero!,
+    if (timerPickerSecondLabelOne != null) timerPickerSecondLabelOne!,
+    if (timerPickerSecondLabelTwo != null) timerPickerSecondLabelTwo!,
+    if (timerPickerSecondLabelFew != null) timerPickerSecondLabelFew!,
+    if (timerPickerSecondLabelMany != null) timerPickerSecondLabelMany!,
+    if (timerPickerSecondLabelOther != null) timerPickerSecondLabelOther!,
   ];
 
   /// A [LocalizationsDelegate] for [CupertinoLocalizations].
@@ -444,18 +444,18 @@ class _GlobalCupertinoLocalizationsDelegate extends LocalizationsDelegate<Cupert
         'might be $localeName',
       );
 
-      intl.DateFormat fullYearFormat;
-      intl.DateFormat dayFormat;
-      intl.DateFormat mediumDateFormat;
+      late intl.DateFormat fullYearFormat;
+      late intl.DateFormat dayFormat;
+      late intl.DateFormat mediumDateFormat;
       // We don't want any additional decoration here. The am/pm is handled in
       // the date picker. We just want an hour number localized.
-      intl.DateFormat singleDigitHourFormat;
-      intl.DateFormat singleDigitMinuteFormat;
-      intl.DateFormat doubleDigitMinuteFormat;
-      intl.DateFormat singleDigitSecondFormat;
-      intl.NumberFormat decimalFormat;
+      late intl.DateFormat singleDigitHourFormat;
+      late intl.DateFormat singleDigitMinuteFormat;
+      late intl.DateFormat doubleDigitMinuteFormat;
+      late intl.DateFormat singleDigitSecondFormat;
+      late intl.NumberFormat decimalFormat;
 
-      void loadFormats(String locale) {
+      void loadFormats(String? locale) {
         fullYearFormat = intl.DateFormat.y(locale);
         dayFormat = intl.DateFormat.d(locale);
         mediumDateFormat = intl.DateFormat.MMMEd(locale);
@@ -485,7 +485,7 @@ class _GlobalCupertinoLocalizationsDelegate extends LocalizationsDelegate<Cupert
         doubleDigitMinuteFormat,
         singleDigitSecondFormat,
         decimalFormat,
-      ));
+      )!);
     });
   }
 

packages/flutter_localizations/lib/src/l10n/cupertino_en.arb

 {
+  "@datePickerHourSemanticsLabelZero": {
+    "optional": true
+  },
   "datePickerHourSemanticsLabelOne": "$hour o'clock",
+  "@datePickerHourSemanticsLabelOne": {
+    "optional": true
+  },
+  "@datePickerHourSemanticsLabelTwo": {
+    "optional": true
+  },
+  "@datePickerHourSemanticsLabelFew": {
+    "optional": true
+  },
+  "@datePickerHourSemanticsLabelMany": {
+    "optional": true
+  },
   "datePickerHourSemanticsLabelOther": "$hour o'clock",
   "@datePickerHourSemanticsLabel": {
     "description": "Accessibility announcement for the selected hour on a time picker such as '5 o'clock' or '5点'",
     "plural": "hour"
   },
 
+  "@datePickerMinuteSemanticsLabelZero": {
+    "optional": true
+  },
   "datePickerMinuteSemanticsLabelOne": "1 minute",
+  "@datePickerMinuteSemanticsLabelOne": {
+    "optional": true
+  },
+  "@datePickerMinuteSemanticsLabelTwo": {
+    "optional": true
+  },
+  "@datePickerMinuteSemanticsLabelFew": {
+    "optional": true
+  },
+  "@datePickerMinuteSemanticsLabelMany": {
+    "optional": true
+  },
   "datePickerMinuteSemanticsLabelOther": "$minute minutes",
   "@datePickerMinuteSemanticsLabel": {
     "description": "Accessibility announcement for the selected minute on a time picker such as '15 minutes' or '15分'",
@@ -49,21 +79,66 @@
     "parameters": "tabIndex, tabCount"
   },
 
+  "@timerPickerHourLabelZero": {
+    "optional": true
+  },
   "timerPickerHourLabelOne": "hour",
+  "@timerPickerHourLabelOne": {
+    "optional": true
+  },
+  "@timerPickerHourLabelTwo": {
+    "optional": true
+  },
+  "@timerPickerHourLabelFew": {
+    "optional": true
+  },
+  "@timerPickerHourLabelMany": {
+    "optional": true
+  },
   "timerPickerHourLabelOther": "hours",
   "@timerPickerHourLabel": {
     "description": "The label adjacent to an hour integer number in a countdown timer. The reference abbreviation is what iOS does in the stock clock app's countdown timer.",
     "plural": "hour"
   },
 
+  "@timerPickerMinuteLabelZero": {
+    "optional": true
+  },
   "timerPickerMinuteLabelOne": "min.",
+  "@timerPickerMinuteLabelOne": {
+    "optional": true
+  },
+  "@timerPickerMinuteLabelTwo": {
+    "optional": true
+  },
+  "@timerPickerMinuteLabelFew": {
+    "optional": true
+  },
+  "@timerPickerMinuteLabelMany": {
+    "optional": true
+  },
   "timerPickerMinuteLabelOther": "min.",
   "@timerPickerMinuteLabel": {
     "description": "The label adjacent to a minute integer number in a countdown timer. The reference abbreviation is what iOS does in the stock clock app's countdown timer.",
     "plural": "minute"
   },
 
+  "@timerPickerSecondLabelZero": {
+    "optional": true
+  },
   "timerPickerSecondLabelOne": "sec.",
+  "@timerPickerSecondLabelOne": {
+    "optional": true
+  },
+  "@timerPickerSecondLabelTwo": {
+    "optional": true
+  },
+  "@timerPickerSecondLabelFew": {
+    "optional": true
+  },
+  "@timerPickerSecondLabelMany": {
+    "optional": true
+  },
   "timerPickerSecondLabelOther": "sec.",
   "@timerPickerSecondLabel": {
     "description": "The label adjacent to a second integer number in a countdown timer. The reference abbreviation is what iOS does in the stock clock app's countdown timer.",

packages/flutter_localizations/lib/src/l10n/material_en.arb

@@ -73,7 +73,22 @@
   },
 
   "licensesPackageDetailTextZero": "No licenses",
+  "@licensesPackageDetailTextZero": {
+    "optional": true
+  },
   "licensesPackageDetailTextOne": "1 license",
+  "@licensesPackageDetailTextOne": {
+    "optional": true
+  },
+  "@licensesPackageDetailTextTwo": {
+    "optional": true
+  },
+  "@licensesPackageDetailTextFew": {
+    "optional": true
+  },
+  "@licensesPackageDetailTextMany": {
+    "optional": true
+  },
   "licensesPackageDetailTextOther": "$licenseCount licenses",
   "@licensesPackageDetailText": {
     "description": "The subtitle and detail text for a package displayed on the Flutter licenses page. The value of $licenseCount is an integer which indicates the number of licenses the package has.",
@@ -104,7 +119,22 @@
   },
 
   "selectedRowCountTitleZero": "No items selected",
+  "@selectedRowCountTitleZero": {
+    "optional": true
+  },
   "selectedRowCountTitleOne": "1 item selected",
+  "@selectedRowCountTitleOne": {
+    "optional": true
+  },
+  "@selectedRowCountTitleTwo": {
+    "optional": true
+  },
+  "@selectedRowCountTitleFew": {
+    "optional": true
+  },
+  "@selectedRowCountTitleMany": {
+    "optional": true
+  },
   "selectedRowCountTitleOther": "$selectedRowCount items selected",
   "@selectedRowCountTitle": {
     "description": "The title for the header of a paginated data table when the user is selecting rows. The value of $selectedRowCount is an integer which indicates the number of data table row elements that have been selected.",
@@ -389,7 +419,22 @@
   },
 
   "remainingTextFieldCharacterCountZero": "No characters remaining",
+  "@remainingTextFieldCharacterCountZero": {
+    "optional": true
+  },
   "remainingTextFieldCharacterCountOne": "1 character remaining",
+  "@remainingTextFieldCharacterCountOne": {
+    "optional": true
+  },
+  "@remainingTextFieldCharacterCountTwo": {
+    "optional": true
+  },
+  "@remainingTextFieldCharacterCountFew": {
+    "optional": true
+  },
+  "@remainingTextFieldCharacterCountMany": {
+    "optional": true
+  },
   "remainingTextFieldCharacterCountOther": "$remainingCount characters remaining",
   "@remainingTextFieldCharacterCount": {
     "description": "The label for the TextField's character counter. remainingCharacters is a integer representing how many more characters the user can type into the text field before using up a given budget. All values are greater than or equal to zero.",

packages/flutter_localizations/lib/src/l10n/material_ps.arb

 {
   "scriptCategory": "tall",
   "timeOfDayFormat": "HH:mm",
+  "anteMeridiemAbbreviation": "AM",
   "@anteMeridiemAbbreviation": {"notUsed":"Pashto time format does not use a.m. indicator"},
+  "postMeridiemAbbreviation": "PM",
   "@postMeridiemAbbreviation": {"notUsed":"Pashto time format does not use p.m. indicator"},
   "openAppDrawerTooltip": "د پرانیستی نیینګ مینو",
   "backButtonTooltip": "شاته",

packages/flutter_localizations/lib/src/material_localizations.dart

@@ -87,16 +87,16 @@ abstract class GlobalMaterialLocalizations implements MaterialLocalizations {
   /// The [narrowWeekdays] and [firstDayOfWeekIndex] properties use the values
   /// from the [intl.DateFormat] used by [formatFullDate].
   const GlobalMaterialLocalizations({
-    @required String localeName,
-    @required intl.DateFormat fullYearFormat,
-    @required intl.DateFormat compactDateFormat,
-    @required intl.DateFormat shortDateFormat,
-    @required intl.DateFormat mediumDateFormat,
-    @required intl.DateFormat longDateFormat,
-    @required intl.DateFormat yearMonthFormat,
-    @required intl.DateFormat shortMonthDayFormat,
-    @required intl.NumberFormat decimalFormat,
-    @required intl.NumberFormat twoDigitZeroPaddedFormat,
+    required String localeName,
+    required intl.DateFormat fullYearFormat,
+    required intl.DateFormat compactDateFormat,
+    required intl.DateFormat shortDateFormat,
+    required intl.DateFormat mediumDateFormat,
+    required intl.DateFormat longDateFormat,
+    required intl.DateFormat yearMonthFormat,
+    required intl.DateFormat shortMonthDayFormat,
+    required intl.NumberFormat decimalFormat,
+    required intl.NumberFormat twoDigitZeroPaddedFormat,
   }) : assert(localeName != null),
        _localeName = localeName,
        assert(fullYearFormat != null),
@@ -140,7 +140,6 @@ abstract class GlobalMaterialLocalizations implements MaterialLocalizations {
         final int hour = timeOfDay.hourOfPeriod;
         return formatDecimal(hour == 0 ? 12 : hour);
     }
-    return null;
   }
 
   @override
@@ -184,9 +183,9 @@ abstract class GlobalMaterialLocalizations implements MaterialLocalizations {
   }
 
   @override
-  DateTime parseCompactDate(String inputString) {
+  DateTime? parseCompactDate(String? inputString) {
     try {
-      return _compactDateFormat.parseStrict(inputString);
+      return inputString != null ? _compactDateFormat.parseStrict(inputString) : null;
     } on FormatException {
       return null;
     }
@@ -219,28 +218,26 @@ abstract class GlobalMaterialLocalizations implements MaterialLocalizations {
     final String minute = formatMinute(timeOfDay);
     switch (timeOfDayFormat(alwaysUse24HourFormat: alwaysUse24HourFormat)) {
       case TimeOfDayFormat.h_colon_mm_space_a:
-        return '$hour:$minute ${_formatDayPeriod(timeOfDay)}';
+        return '$hour:$minute ${_formatDayPeriod(timeOfDay)!}';
       case TimeOfDayFormat.H_colon_mm:
       case TimeOfDayFormat.HH_colon_mm:
         return '$hour:$minute';
       case TimeOfDayFormat.HH_dot_mm:
         return '$hour.$minute';
       case TimeOfDayFormat.a_space_h_colon_mm:
-        return '${_formatDayPeriod(timeOfDay)} $hour:$minute';
+        return '${_formatDayPeriod(timeOfDay)!} $hour:$minute';
       case TimeOfDayFormat.frenchCanadian:
         return '$hour h $minute';
     }
-    return null;
   }
 
-  String _formatDayPeriod(TimeOfDay timeOfDay) {
+  String? _formatDayPeriod(TimeOfDay timeOfDay) {
     switch (timeOfDay.period) {
       case DayPeriod.am:
         return anteMeridiemAbbreviation;
       case DayPeriod.pm:
         return postMeridiemAbbreviation;
     }
-    return null;
   }
 
   /// The raw version of [dateRangeStartDateSemanticLabel], with `$formattedDate` verbatim
@@ -288,7 +285,7 @@ abstract class GlobalMaterialLocalizations implements MaterialLocalizations {
 
   @override
   String pageRowsInfoTitle(int firstRow, int lastRow, int rowCount, bool rowCountIsApproximate) {
-    String text = rowCountIsApproximate ? pageRowsInfoTitleApproximateRaw : null;
+    String? text = rowCountIsApproximate ? pageRowsInfoTitleApproximateRaw : null;
     text ??= pageRowsInfoTitleRaw;
     assert(text != null, 'A $_localeName localization was not found for pageRowsInfoTitle or pageRowsInfoTitleApproximate');
     return text
@@ -303,7 +300,7 @@ abstract class GlobalMaterialLocalizations implements MaterialLocalizations {
   String get tabLabelRaw;
 
   @override
-  String tabLabel({ int tabIndex, int tabCount }) {
+  String tabLabel({ required int tabIndex, required int tabCount }) {
     assert(tabIndex >= 1);
     assert(tabCount >= 1);
     final String template = tabLabelRaw;
@@ -325,7 +322,7 @@ abstract class GlobalMaterialLocalizations implements MaterialLocalizations {
   ///  * [selectedRowCountTitleMany], the "many" form
   ///  * [selectedRowCountTitleOther], the "other" form
   @protected
-  String get selectedRowCountTitleZero => null;
+  String? get selectedRowCountTitleZero => null;
 
   /// The "one" form of [selectedRowCountTitle].
   ///
@@ -340,7 +337,7 @@ abstract class GlobalMaterialLocalizations implements MaterialLocalizations {
   ///  * [selectedRowCountTitleMany], the "many" form
   ///  * [selectedRowCountTitleOther], the "other" form
   @protected
-  String get selectedRowCountTitleOne => null;
+  String? get selectedRowCountTitleOne => null;
 
   /// The "two" form of [selectedRowCountTitle].
   ///
@@ -355,7 +352,7 @@ abstract class GlobalMaterialLocalizations implements MaterialLocalizations {
   ///  * [selectedRowCountTitleMany], the "many" form
   ///  * [selectedRowCountTitleOther], the "other" form
   @protected
-  String get selectedRowCountTitleTwo => null;
+  String? get selectedRowCountTitleTwo => null;
 
   /// The "few" form of [selectedRowCountTitle].
   ///
@@ -370,7 +367,7 @@ abstract class GlobalMaterialLocalizations implements MaterialLocalizations {
   ///  * [selectedRowCountTitleMany], the "many" form
   ///  * [selectedRowCountTitleOther], the "other" form
   @protected
-  String get selectedRowCountTitleFew => null;
+  String? get selectedRowCountTitleFew => null;
 
   /// The "many" form of [selectedRowCountTitle].
   ///
@@ -385,7 +382,7 @@ abstract class GlobalMaterialLocalizations implements MaterialLocalizations {
   ///  * [selectedRowCountTitleFew], the "few" form
   ///  * [selectedRowCountTitleOther], the "other" form
   @protected
-  String get selectedRowCountTitleMany => null;
+  String? get selectedRowCountTitleMany => null;
 
   /// The "other" form of [selectedRowCountTitle].
   ///
@@ -458,7 +455,7 @@ abstract class GlobalMaterialLocalizations implements MaterialLocalizations {
   ///  * [licensesPackageDetailTextMany], the "many" form
   ///  * [licensesPackageDetailTextOther], the "other" form
   @protected
-  String get licensesPackageDetailTextZero => null;
+  String? get licensesPackageDetailTextZero => null;
 
   /// The "one" form of [licensesPackageDetailText].
   ///
@@ -473,7 +470,7 @@ abstract class GlobalMaterialLocalizations implements MaterialLocalizations {
   ///  * [licensesPackageDetailTextMany], the "many" form
   ///  * [licensesPackageDetailTextOther], the "other" form
   @protected
-  String get licensesPackageDetailTextOne => null;
+  String? get licensesPackageDetailTextOne => null;
 
   /// The "two" form of [licensesPackageDetailText].
   ///
@@ -489,7 +486,7 @@ abstract class GlobalMaterialLocalizations implements MaterialLocalizations {
   ///  * [licensesPackageDetailTextMany], the "many" form
   ///  * [licensesPackageDetailTextOther], the "other" form
   @protected
-  String get licensesPackageDetailTextTwo => null;
+  String? get licensesPackageDetailTextTwo => null;
 
   /// The "many" form of [licensesPackageDetailText].
   ///
@@ -505,7 +502,7 @@ abstract class GlobalMaterialLocalizations implements MaterialLocalizations {
   ///  * [licensesPackageDetailTextMany], the "many" form
   ///  * [licensesPackageDetailTextOther], the "other" form
   @protected
-  String get licensesPackageDetailTextMany => null;
+  String? get licensesPackageDetailTextMany => null;
 
   /// The "few" form of [licensesPackageDetailText].
   ///
@@ -521,7 +518,7 @@ abstract class GlobalMaterialLocalizations implements MaterialLocalizations {
   ///  * [licensesPackageDetailTextMany], the "many" form
   ///  * [licensesPackageDetailTextOther], the "other" form
   @protected
-  String get licensesPackageDetailTextFew => null;
+  String? get licensesPackageDetailTextFew => null;
 
   /// The "other" form of [licensesPackageDetailText].
   ///
@@ -555,7 +552,7 @@ abstract class GlobalMaterialLocalizations implements MaterialLocalizations {
 
   /// The "zero" form of [remainingTextFieldCharacterCount].
   ///
-  /// This form is required.
+  /// This form is optional.
   ///
   /// See also:
   ///
@@ -567,7 +564,7 @@ abstract class GlobalMaterialLocalizations implements MaterialLocalizations {
   ///  * [remainingTextFieldCharacterCountMany], the "many" form
   ///  * [remainingTextFieldCharacterCountOther], the "other" form
   @protected
-  String get remainingTextFieldCharacterCountZero;
+  String? get remainingTextFieldCharacterCountZero => null;
 
   /// The "one" form of [remainingTextFieldCharacterCount].
   ///
@@ -582,7 +579,7 @@ abstract class GlobalMaterialLocalizations implements MaterialLocalizations {
   ///  * [remainingTextFieldCharacterCountMany], the "many" form
   ///  * [remainingTextFieldCharacterCountOther], the "other" form
   @protected
-  String get remainingTextFieldCharacterCountOne => null;
+  String? get remainingTextFieldCharacterCountOne => null;
 
   /// The "two" form of [remainingTextFieldCharacterCount].
   ///
@@ -598,7 +595,7 @@ abstract class GlobalMaterialLocalizations implements MaterialLocalizations {
   ///  * [remainingTextFieldCharacterCountMany], the "many" form
   ///  * [remainingTextFieldCharacterCountOther], the "other" form
   @protected
-  String get remainingTextFieldCharacterCountTwo => null;
+  String? get remainingTextFieldCharacterCountTwo => null;
 
   /// The "many" form of [remainingTextFieldCharacterCount].
   ///
@@ -614,7 +611,7 @@ abstract class GlobalMaterialLocalizations implements MaterialLocalizations {
   ///  * [remainingTextFieldCharacterCountMany], the "many" form
   ///  * [remainingTextFieldCharacterCountOther], the "other" form
   @protected
-  String get remainingTextFieldCharacterCountMany => null;
+  String? get remainingTextFieldCharacterCountMany => null;
 
   /// The "few" form of [remainingTextFieldCharacterCount].
   ///
@@ -630,7 +627,7 @@ abstract class GlobalMaterialLocalizations implements MaterialLocalizations {
   ///  * [remainingTextFieldCharacterCountMany], the "many" form
   ///  * [remainingTextFieldCharacterCountOther], the "other" form
   @protected
-  String get remainingTextFieldCharacterCountFew => null;
+  String? get remainingTextFieldCharacterCountFew => null;
 
   /// The "other" form of [remainingTextFieldCharacterCount].
   ///
@@ -714,7 +711,6 @@ TimeOfDayFormat _get24HourVersionOf(TimeOfDayFormat original) {
     case TimeOfDayFormat.a_space_h_colon_mm:
       return TimeOfDayFormat.HH_colon_mm;
   }
-  return TimeOfDayFormat.HH_colon_mm;
 }
 
 class _MaterialLocalizationsDelegate extends LocalizationsDelegate<MaterialLocalizations> {
@@ -795,7 +791,7 @@ class _MaterialLocalizationsDelegate extends LocalizationsDelegate<MaterialLocal
         shortMonthDayFormat,
         decimalFormat,
         twoDigitZeroPaddedFormat,
-      ));
+      )!);
     });
   }
 

packages/flutter_localizations/lib/src/utils/date_localizations.dart

@@ -28,7 +28,7 @@ void loadDateIntlDataIfNotLoaded() {
         // Strip scriptCode from the locale, as we do not distinguish between scripts
         // for dates.
         final List<String> codes = locale.split('_');
-        String countryCode;
+        String? countryCode;
         if (codes.length == 2) {
           countryCode = codes[1].length < 4 ? codes[1] : null;
         } else if (codes.length == 3) {

packages/flutter_localizations/lib/src/widgets_localizations.dart

@@ -43,7 +43,7 @@ class GlobalWidgetsLocalizations implements WidgetsLocalizations {
 
   @override
   TextDirection get textDirection => _textDirection;
-  TextDirection _textDirection;
+  late TextDirection _textDirection;
 
   /// Creates an object that provides localized resource values for the
   /// lowest levels of the Flutter framework.

packages/flutter_localizations/pubspec.yaml

@@ -2,7 +2,7 @@ name: flutter_localizations
 
 environment:
   # The pub client defaults to an <2.0.0 sdk constraint which we need to explicitly overwrite.
-  sdk: ">=2.2.0 <3.0.0"
+  sdk: ">=2.12.0-0 <3.0.0"
 
 dependencies:
   # To update these, use "flutter update-packages --force-upgrade".

packages/flutter_localizations/test/basics_test.dart

@@ -63,7 +63,7 @@ void main() {
       )
     );
 
-    await tester.binding.setLocale('zh', null);
+    await tester.binding.setLocale('zh', '');
     await tester.pump();
     await tester.binding.setLocale('es', 'US');
     await tester.pump();
@@ -87,18 +87,18 @@ class _DummyLocalizationsDelegate extends LocalizationsDelegate<DummyLocalizatio
 class DummyLocalizations {}
 
 class LocalizationTracker extends StatefulWidget {
-  const LocalizationTracker({Key key}) : super(key: key);
+  const LocalizationTracker({Key? key}) : super(key: key);
 
   @override
   State<StatefulWidget> createState() => LocalizationTrackerState();
 }
 
 class LocalizationTrackerState extends State<LocalizationTracker> {
-  double captionFontSize;
+  late double captionFontSize;
 
   @override
   Widget build(BuildContext context) {
-    captionFontSize = Theme.of(context).textTheme.caption.fontSize;
+    captionFontSize = Theme.of(context).textTheme.caption!.fontSize!;
     return Container();
   }
 }

packages/flutter_localizations/test/material/date_picker_test.dart

@@ -9,9 +9,9 @@ import 'package:flutter_localizations/flutter_localizations.dart';
 import 'package:flutter_test/flutter_test.dart';
 
 void main() {
-  DateTime firstDate;
-  DateTime lastDate;
-  DateTime initialDate;
+  late DateTime firstDate;
+  late DateTime lastDate;
+  late DateTime initialDate;
 
   setUp(() {
     firstDate = DateTime(2001, DateTime.january, 1);
@@ -53,10 +53,10 @@ void main() {
 
     for (final Locale locale in testLocales.keys) {
       testWidgets('shows dates for $locale', (WidgetTester tester) async {
-        final List<String> expectedDaysOfWeek = testLocales[locale]['expectedDaysOfWeek'] as List<String>;
-        final List<String> expectedDaysOfMonth = testLocales[locale]['expectedDaysOfMonth'] as List<String>;
-        final String expectedMonthYearHeader = testLocales[locale]['expectedMonthYearHeader'] as String;
-        final TextDirection textDirection = testLocales[locale]['textDirection'] as TextDirection;
+        final List<String> expectedDaysOfWeek = testLocales[locale]!['expectedDaysOfWeek'] as List<String>;
+        final List<String> expectedDaysOfMonth = testLocales[locale]!['expectedDaysOfMonth'] as List<String>;
+        final String expectedMonthYearHeader = testLocales[locale]!['expectedMonthYearHeader'] as String;
+        final TextDirection textDirection = testLocales[locale]!['textDirection'] as TextDirection;
         final DateTime baseDate = DateTime(2017, 9, 27);
 
         await _pumpBoilerplate(tester, CalendarDatePicker(
@@ -72,7 +72,7 @@ void main() {
           expect(find.text(dayOfWeek), findsWidgets);
         }
 
-        Offset previousCellOffset;
+        Offset? previousCellOffset;
         for (final String dayOfMonth in expectedDaysOfMonth) {
           final Finder dayCell = find.descendant(of: find.byType(GridView), matching: find.text(dayOfMonth));
           expect(dayCell, findsOneWidget);

packages/flutter_localizations/test/material/date_time_test.dart

@@ -163,7 +163,7 @@ void main() {
 
   // Regression test for https://github.com/flutter/flutter/issues/67644.
   testWidgets('en_US is initialized correctly by Flutter when DateFormat is used', (WidgetTester tester) async {
-    DateFormat dateFormat;
+    late DateFormat dateFormat;
 
     await tester.pumpWidget(MaterialApp(
       supportedLocales: const <Locale>[
@@ -180,7 +180,7 @@ void main() {
       }),
     ));
 
-    expect(dateFormat?.locale, 'en_US');
+    expect(dateFormat.locale, 'en_US');
   });
 }
 

packages/flutter_localizations/test/material/time_picker_test.dart

@@ -9,13 +9,13 @@ import 'package:flutter_test/flutter_test.dart';
 
 class _TimePickerLauncher extends StatelessWidget {
   const _TimePickerLauncher({
-    Key key,
+    Key? key,
     this.onChanged,
-    this.locale,
+    required this.locale,
     this.entryMode = TimePickerEntryMode.dial,
   }) : super(key: key);
 
-  final ValueChanged<TimeOfDay> onChanged;
+  final ValueChanged<TimeOfDay?>? onChanged;
   final Locale locale;
   final TimePickerEntryMode entryMode;
 
@@ -32,7 +32,7 @@ class _TimePickerLauncher extends StatelessWidget {
               return ElevatedButton(
                 child: const Text('X'),
                 onPressed: () async {
-                  onChanged(await showTimePicker(
+                  onChanged?.call(await showTimePicker(
                     context: context,
                     initialEntryMode: entryMode,
                     initialTime: const TimeOfDay(hour: 7, minute: 0),
@@ -49,7 +49,7 @@ class _TimePickerLauncher extends StatelessWidget {
 
 Future<Offset> startPicker(
   WidgetTester tester,
-  ValueChanged<TimeOfDay> onChanged, {
+  ValueChanged<TimeOfDay?> onChanged, {
     Locale locale = const Locale('en', 'US'),
 }) async {
   await tester.pumpWidget(_TimePickerLauncher(onChanged: onChanged, locale: locale,));
@@ -89,7 +89,7 @@ void main() {
     ];
 
     for (final Locale locale in locales) {
-      final Offset center = await startPicker(tester, (TimeOfDay time) { }, locale: locale);
+      final Offset center = await startPicker(tester, (TimeOfDay? time) { }, locale: locale);
       final Text stringFragmentText = tester.widget(stringFragmentTextFinder);
       final double hourLeftOffset = tester.getTopLeft(hourControlFinder).dx;
       final double minuteLeftOffset = tester.getTopLeft(minuteControlFinder).dx;
@@ -133,8 +133,8 @@ void main() {
       await finishPicker(tester);
     }
 
-    tester.binding.window.physicalSizeTestValue = null;
-    tester.binding.window.devicePixelRatioTestValue = null;
+    tester.binding.window.clearPhysicalSizeTestValue();
+    tester.binding.window.clearDevicePixelRatioTestValue();
   });
 
   testWidgets('can localize the header in all known formats - landscape', (WidgetTester tester) async {
@@ -161,7 +161,7 @@ void main() {
     ];
 
     for (final Locale locale in locales) {
-      final Offset center = await startPicker(tester, (TimeOfDay time) { }, locale: locale);
+      final Offset center = await startPicker(tester, (TimeOfDay? time) { }, locale: locale);
       final Text stringFragmentText = tester.widget(stringFragmentTextFinder);
       final double hourLeftOffset = tester.getTopLeft(hourControlFinder).dx;
       final double hourTopOffset = tester.getTopLeft(hourControlFinder).dy;
@@ -210,8 +210,8 @@ void main() {
       await finishPicker(tester);
     }
 
-    tester.binding.window.physicalSizeTestValue = null;
-    tester.binding.window.devicePixelRatioTestValue = null;
+    tester.binding.window.clearPhysicalSizeTestValue();
+    tester.binding.window.clearDevicePixelRatioTestValue();
   });
 
   testWidgets('can localize input mode in all known formats', (WidgetTester tester) async {
@@ -234,7 +234,7 @@ void main() {
     ];
 
     for (final Locale locale in locales) {
-      await tester.pumpWidget(_TimePickerLauncher(onChanged: (TimeOfDay time) { }, locale: locale, entryMode: TimePickerEntryMode.input));
+      await tester.pumpWidget(_TimePickerLauncher(onChanged: (TimeOfDay? time) { }, locale: locale, entryMode: TimePickerEntryMode.input));
       await tester.tap(find.text('X'));
       await tester.pumpAndSettle(const Duration(seconds: 1));
 
@@ -292,8 +292,8 @@ void main() {
       // 12:00 AM position. Because there's only one ring, no matter where you
       // tap the time will be the same.
       for (int i = 1; i < 10; i++) {
-        TimeOfDay result;
-        final Offset center = await startPicker(tester, (TimeOfDay time) { result = time; }, locale: locale);
+        TimeOfDay? result;
+        final Offset center = await startPicker(tester, (TimeOfDay? time) { result = time; }, locale: locale);
         final Size size = tester.getSize(find.byKey(const Key('time-picker-dial')));
         final double dy = (size.height / 2.0 / 10) * i;
         await tester.tapAt(Offset(center.dx, center.dy - dy));
@@ -348,13 +348,13 @@ void main() {
     final dynamic dialPainter = dialPaint.painter;
     final List<dynamic> primaryLabels = dialPainter.primaryLabels as List<dynamic>;
     expect(
-      primaryLabels.map<String>((dynamic tp) => ((tp.painter as TextPainter).text as TextSpan).text),
+      primaryLabels.map<String>((dynamic tp) => ((tp.painter as TextPainter).text! as TextSpan).text!),
       labels12To11,
     );
 
     final List<dynamic> secondaryLabels = dialPainter.secondaryLabels as List<dynamic>;
     expect(
-      secondaryLabels.map<String>((dynamic tp) => ((tp.painter as TextPainter).text as TextSpan).text),
+      secondaryLabels.map<String>((dynamic tp) => ((tp.painter as TextPainter).text! as TextSpan).text!),
       labels12To11,
     );
   });
@@ -366,13 +366,13 @@ void main() {
     final dynamic dialPainter = dialPaint.painter;
     final List<dynamic> primaryLabels = dialPainter.primaryLabels as List<dynamic>;
     expect(
-      primaryLabels.map<String>((dynamic tp) => ((tp.painter as TextPainter).text as TextSpan).text),
+      primaryLabels.map<String>((dynamic tp) => ((tp.painter as TextPainter).text! as TextSpan).text!),
       labels00To22TwoDigit,
     );
 
     final List<dynamic> secondaryLabels = dialPainter.secondaryLabels as List<dynamic>;
     expect(
-      secondaryLabels.map<String>((dynamic tp) => ((tp.painter as TextPainter).text as TextSpan).text),
+      secondaryLabels.map<String>((dynamic tp) => ((tp.painter as TextPainter).text! as TextSpan).text!),
       labels00To22TwoDigit,
     );
   });

packages/flutter_localizations/test/override_test.dart

@@ -53,10 +53,10 @@ class FooMaterialLocalizationsDelegate extends LocalizationsDelegate<MaterialLoc
 }
 
 Widget buildFrame({
-  Locale locale,
+  Locale? locale,
   Iterable<LocalizationsDelegate<dynamic>> delegates = GlobalMaterialLocalizations.delegates,
-  WidgetBuilder buildContent,
-  LocaleResolutionCallback localeResolutionCallback,
+  required WidgetBuilder buildContent,
+  LocaleResolutionCallback? localeResolutionCallback,
   Iterable<Locale> supportedLocales = const <Locale>[
     Locale('en', 'US'),
     Locale('es', 'ES'),
@@ -210,7 +210,7 @@ void main() {
     await tester.pumpWidget(
       buildFrame(
         // Accept whatever locale we're given
-        localeResolutionCallback: (Locale locale, Iterable<Locale> supportedLocales) => locale,
+        localeResolutionCallback: (Locale? locale, Iterable<Locale> supportedLocales) => locale,
         delegates: <FooMaterialLocalizationsDelegate>[
           const FooMaterialLocalizationsDelegate(supportedLanguage: 'allLanguages'),
         ],

packages/flutter_localizations/test/text_test.dart

@@ -92,7 +92,7 @@ void main() {
     expect(topRight, const Offset(477.0, 347.5));
     expect(bottomLeft, const Offset(392.0, 364.5));
     expect(bottomRight, const Offset(477.0, 364.5));
-  }, skip: !isLinux);
+  });
 
   testWidgets('Text baseline with EN locale', (WidgetTester tester) async {
     // This test in combination with 'Text baseline with CJK locale' verify the baselines
@@ -164,7 +164,6 @@ void main() {
     Offset bottomLeft = tester.getBottomLeft(find.text('hello, world'));
     Offset bottomRight = tester.getBottomRight(find.text('hello, world'));
 
-
     expect(topLeft, const Offset(392.0, 300.0));
     expect(topRight, const Offset(584.0, 300.0));
     expect(bottomLeft, const Offset(392.0, 316));
@@ -179,5 +178,5 @@ void main() {
     expect(topRight, const Offset(472.0, 348.0));
     expect(bottomLeft, const Offset(392.0, 364.0));
     expect(bottomRight, const Offset(472.0, 364.0));
-  }, skip: !isLinux);
+  });
 }

packages/flutter_localizations/test/widgets_test.dart

@@ -13,19 +13,21 @@ class TestLocalizations {
   TestLocalizations(this.locale, this.prefix);
 
   final Locale locale;
-  final String prefix;
+  final String? prefix;
 
-  static Future<TestLocalizations> loadSync(Locale locale, String prefix) {
+  static Future<TestLocalizations> loadSync(Locale locale, String? prefix) {
     return SynchronousFuture<TestLocalizations>(TestLocalizations(locale, prefix));
   }
 
-  static Future<TestLocalizations> loadAsync(Locale locale, String prefix) {
-    return Future<TestLocalizations>.delayed(const Duration(milliseconds: 100))
-      .then((_) => TestLocalizations(locale, prefix));
+  static Future<TestLocalizations> loadAsync(Locale locale, String? prefix) {
+    return Future<TestLocalizations>.delayed(
+      const Duration(milliseconds: 100),
+      () => TestLocalizations(locale, prefix)
+    );
   }
 
   static TestLocalizations of(BuildContext context) {
-    return Localizations.of<TestLocalizations>(context, TestLocalizations);
+    return Localizations.of<TestLocalizations>(context, TestLocalizations)!;
   }
 
   String get message => '${prefix ?? ""}$locale';
@@ -34,7 +36,7 @@ class TestLocalizations {
 class SyncTestLocalizationsDelegate extends LocalizationsDelegate<TestLocalizations> {
   SyncTestLocalizationsDelegate([this.prefix]);
 
-  final String prefix; // Changing this value triggers a rebuild
+  final String? prefix; // Changing this value triggers a rebuild
   final List<bool> shouldReloadValues = <bool>[];
 
   @override
@@ -56,7 +58,7 @@ class SyncTestLocalizationsDelegate extends LocalizationsDelegate<TestLocalizati
 class AsyncTestLocalizationsDelegate extends LocalizationsDelegate<TestLocalizations> {
   AsyncTestLocalizationsDelegate([this.prefix]);
 
-  final String prefix; // Changing this value triggers a rebuild
+  final String? prefix; // Changing this value triggers a rebuild
   final List<bool> shouldReloadValues = <bool>[];
 
   @override
@@ -85,12 +87,14 @@ class MoreLocalizations {
   }
 
   static Future<MoreLocalizations> loadAsync(Locale locale) {
-    return Future<MoreLocalizations>.delayed(const Duration(milliseconds: 100))
-      .then((_) => MoreLocalizations(locale));
+    return Future<MoreLocalizations>.delayed(
+      const Duration(milliseconds: 100),
+      () => MoreLocalizations(locale)
+    );
   }
 
   static MoreLocalizations of(BuildContext context) {
-    return Localizations.of<MoreLocalizations>(context, MoreLocalizations);
+    return Localizations.of<MoreLocalizations>(context, MoreLocalizations)!;
   }
 
   String get message => '$locale';
@@ -139,10 +143,10 @@ class OnlyRTLDefaultWidgetsLocalizationsDelegate extends LocalizationsDelegate<W
 }
 
 Widget buildFrame({
-  Locale locale,
-  Iterable<LocalizationsDelegate<dynamic>> delegates,
-  WidgetBuilder buildContent,
-  LocaleResolutionCallback localeResolutionCallback,
+  Locale? locale,
+  Iterable<LocalizationsDelegate<dynamic>>? delegates,
+  required WidgetBuilder buildContent,
+  LocaleResolutionCallback? localeResolutionCallback,
   List<Locale> supportedLocales = const <Locale>[
     Locale('en', 'US'),
     Locale('en', 'GB'),
@@ -183,7 +187,7 @@ class SyncLoadTestState extends State<SyncLoadTest> {
 
 void main() {
   testWidgets('Localizations.localeFor in a WidgetsApp with system locale', (WidgetTester tester) async {
-    BuildContext pageContext;
+    late BuildContext pageContext;
 
     await tester.pumpWidget(
       buildFrame(
@@ -205,7 +209,7 @@ void main() {
 
   testWidgets('Localizations.localeFor in a WidgetsApp with an explicit locale', (WidgetTester tester) async {
     const Locale locale = Locale('en', 'US');
-    BuildContext pageContext;
+    late BuildContext pageContext;
 
     await tester.pumpWidget(
       buildFrame(
@@ -477,7 +481,7 @@ void main() {
   });
 
   testWidgets('Directionality tracks system locale', (WidgetTester tester) async {
-    BuildContext pageContext;
+    late BuildContext pageContext;
 
     await tester.pumpWidget(
       buildFrame(
@@ -507,7 +511,7 @@ void main() {
   testWidgets('localeResolutionCallback override', (WidgetTester tester) async {
     await tester.pumpWidget(
       buildFrame(
-        localeResolutionCallback: (Locale newLocale, Iterable<Locale> supportedLocales) {
+        localeResolutionCallback: (Locale? newLocale, Iterable<Locale> supportedLocales) {
           return const Locale('foo', 'BAR');
         },
         buildContent: (BuildContext context) {
@@ -562,7 +566,7 @@ void main() {
     await tester.pumpWidget(
       buildFrame(
         // Accept whatever locale we're given
-        localeResolutionCallback: (Locale locale, Iterable<Locale> supportedLocales) => locale,
+        localeResolutionCallback: (Locale? locale, Iterable<Locale> supportedLocales) => locale,
         delegates: const <LocalizationsDelegate<dynamic>>[
           GlobalWidgetsLocalizations.delegate,
         ],
@@ -571,7 +575,7 @@ void main() {
             context: context,
             child: Builder(
               builder: (BuildContext context) {
-                final Locale locale = Localizations.localeOf(context);
+                final Locale locale = Localizations.localeOf(context)!;
                 final TextDirection direction = WidgetsLocalizations.of(context).textDirection;
                 return Text('$locale $direction');
               },
@@ -602,7 +606,7 @@ void main() {
     await tester.pumpWidget(
       buildFrame(
         // Accept whatever locale we're given
-        localeResolutionCallback: (Locale locale, Iterable<Locale> supportedLocales) => locale,
+        localeResolutionCallback: (Locale? locale, Iterable<Locale> supportedLocales) => locale,
         buildContent: (BuildContext context) {
           return Localizations.override(
             context: context,
@@ -612,7 +616,7 @@ void main() {
             ],
             child: Builder(
               builder: (BuildContext context) {
-                final Locale locale = Localizations.localeOf(context);
+                final Locale locale = Localizations.localeOf(context)!;
                 final TextDirection direction = WidgetsLocalizations.of(context).textDirection;
                 return Text('$locale $direction');
               },
@@ -643,12 +647,12 @@ void main() {
     await tester.pumpWidget(
       buildFrame(
         // Accept whatever locale we're given
-        localeResolutionCallback: (Locale locale, Iterable<Locale> supportedLocales) => locale,
+        localeResolutionCallback: (Locale? locale, Iterable<Locale> supportedLocales) => locale,
         delegates: <OnlyRTLDefaultWidgetsLocalizationsDelegate>[
           const OnlyRTLDefaultWidgetsLocalizationsDelegate(),
         ],
         buildContent: (BuildContext context) {
-          final Locale locale = Localizations.localeOf(context);
+          final Locale locale = Localizations.localeOf(context)!;
           final TextDirection direction = WidgetsLocalizations.of(context).textDirection;
           return Text('$locale $direction');
         },
@@ -680,13 +684,13 @@ void main() {
     await tester.pumpWidget(
       buildFrame(
         // Accept whatever locale we're given
-        localeResolutionCallback: (Locale locale, Iterable<Locale> supportedLocales) => locale,
+        localeResolutionCallback: (Locale? locale, Iterable<Locale> supportedLocales) => locale,
         delegates: <OnlyRTLDefaultWidgetsLocalizationsDelegate>[
           const OnlyRTLDefaultWidgetsLocalizationsDelegate(),
         ],
         buildContent: (BuildContext context) {
-          final Locale locale1 = ui.window.locales.first;
-          final Locale locale2 = ui.window.locales[1];
+          final Locale locale1 = ui.window.locales!.first;
+          final Locale locale2 = ui.window.locales![1];
           return Text('$locale1 $locale2');
         },
       )
@@ -756,7 +760,7 @@ void main() {
           Locale('ja'),
         ],
         buildContent: (BuildContext context) {
-          final Locale locale = Localizations.localeOf(context);
+          final Locale locale = Localizations.localeOf(context)!;
           return Text('$locale');
         },
       )
@@ -779,7 +783,7 @@ void main() {
           Locale('zh', 'TW'),
         ],
         buildContent: (BuildContext context) {
-          final Locale locale = Localizations.localeOf(context);
+          final Locale locale = Localizations.localeOf(context)!;
           return Text('$locale');
         },
       )
@@ -811,7 +815,7 @@ void main() {
           Locale.fromSubtags(languageCode: 'zh', scriptCode: 'Hant', countryCode: 'HK'),
         ],
         buildContent: (BuildContext context) {
-          final Locale locale = Localizations.localeOf(context);
+          final Locale locale = Localizations.localeOf(context)!;
           return Text('$locale');
         },
       )
@@ -952,7 +956,7 @@ void main() {
           Locale.fromSubtags(languageCode: 'zh'),
         ],
         buildContent: (BuildContext context) {
-          final Locale locale = Localizations.localeOf(context);
+          final Locale locale = Localizations.localeOf(context)!;
           return Text('$locale');
         },
       )
@@ -1092,7 +1096,7 @@ void main() {
           Locale('it', 'IT'),
         ],
         buildContent: (BuildContext context) {
-          final Locale locale = Localizations.localeOf(context);
+          final Locale locale = Localizations.localeOf(context)!;
           return Text('$locale');
         },
       )
@@ -1115,7 +1119,7 @@ void main() {
           Locale('it', 'IT'),
         ],
         buildContent: (BuildContext context) {
-          final Locale locale = Localizations.localeOf(context);
+          final Locale locale = Localizations.localeOf(context)!;
           return Text('$locale');
         },
       )
@@ -1148,7 +1152,7 @@ void main() {
           Locale('pt', 'PT'),
         ],
         buildContent: (BuildContext context) {
-          final Locale locale = Localizations.localeOf(context);
+          final Locale locale = Localizations.localeOf(context)!;
           return Text('$locale');
         },
       )
@@ -1215,7 +1219,7 @@ void main() {
           Locale('de', 'DE'),
         ],
         buildContent: (BuildContext context) {
-          final Locale locale = Localizations.localeOf(context);
+          final Locale locale = Localizations.localeOf(context)!;
           return Text('$locale');
         },
       )
@@ -1279,7 +1283,7 @@ void main() {
           Locale('vi'),
         ],
         buildContent: (BuildContext context) {
-          final Locale locale = Localizations.localeOf(context);
+          final Locale locale = Localizations.localeOf(context)!;
           return Text('$locale');
         },
       )
@@ -1425,13 +1429,13 @@ void main() {
           Locale('en', 'AU'),
           Locale('de', 'DE'),
         ],
-        localeResolutionCallback: (Locale locale, Iterable<Locale> supportedLocales) {
+        localeResolutionCallback: (Locale? locale, Iterable<Locale> supportedLocales) {
           if (locale == null)
             return const Locale('und', 'US');
           return const Locale('en', 'US');
         },
         buildContent: (BuildContext context) {
-          final Locale locale = Localizations.localeOf(context);
+          final Locale locale = Localizations.localeOf(context)!;
           return Text('$locale');
         },
       )
@@ -1443,10 +1447,6 @@ void main() {
     await tester.pumpAndSettle();
     expect(find.text('en_US'), findsOneWidget);
 
-    await tester.binding.setLocales(null);
-    await tester.pumpAndSettle();
-    expect(find.text('und_US'), findsOneWidget);
-
     await tester.binding.setLocales(const <Locale>[]);
     await tester.pumpAndSettle();
     expect(find.text('und_US'), findsOneWidget);