Migrate error_handling_io to null safety (#78932)

packages/flutter_tools/lib/src/base/config.dart

@@ -2,8 +2,6 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-// @dart = 2.8
-
 import 'package:file/memory.dart';
 import 'package:meta/meta.dart';
 
@@ -27,9 +25,9 @@ class Config {
   /// home directory.
   factory Config(
     String name, {
-    @required FileSystem fileSystem,
-    @required Logger logger,
-    @required Platform platform,
+    required FileSystem fileSystem,
+    required Logger logger,
+    required Platform platform,
   }) {
     final String filePath = _configPath(platform, fileSystem, name);
     final File file = fileSystem.file(filePath);
@@ -43,8 +41,8 @@ class Config {
   /// Defaults to [BufferLogger], [MemoryFileSystem], and [name]=test.
   factory Config.test({
     String name = 'test',
-    Directory directory,
-    Logger logger,
+    Directory? directory,
+    Logger? logger,
   }) {
     directory ??= MemoryFileSystem.test().directory('/');
     return Config.createForTesting(directory.childFile('.${kConfigDir}_$name'), logger ?? BufferLogger.test());
@@ -58,7 +56,7 @@ class Config {
     }
     try {
       ErrorHandlingFileSystem.noExitOnFailure(() {
-        _values = castStringKeyedMap(json.decode(_file.readAsStringSync()));
+        _values = castStringKeyedMap(json.decode(_file.readAsStringSync())) ?? <String, dynamic>{};
       });
     } on FormatException {
       _logger

packages/flutter_tools/lib/src/build_system/depfile.dart

@@ -2,10 +2,6 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-// @dart = 2.8
-
-import 'package:meta/meta.dart';
-
 import '../base/error_handling_io.dart';
 import '../base/file_system.dart';
 import '../base/logger.dart';
@@ -13,8 +9,8 @@ import '../base/logger.dart';
 /// A service for creating and parsing [Depfile]s.
 class DepfileService {
   DepfileService({
-    @required Logger logger,
-    @required FileSystem fileSystem,
+    required Logger logger,
+    required FileSystem fileSystem,
   }) : _logger = logger,
        _fileSystem = fileSystem;
 
@@ -67,7 +63,7 @@ class DepfileService {
       if (rawUri.trim().isEmpty) {
         continue;
       }
-      final Uri fileUri = Uri.tryParse(rawUri);
+      final Uri? fileUri = Uri.tryParse(rawUri);
       if (fileUri == null) {
         continue;
       }
@@ -102,7 +98,7 @@ class DepfileService {
         .replaceAllMapped(_separatorExpr, (Match match) => '${match.group(1)}\n')
         .split('\n')
     // Expand escape sequences, so that '\ ', for example,ß becomes ' '
-        .map<String>((String path) => path.replaceAllMapped(_escapeExpr, (Match match) => match.group(1)).trim())
+        .map<String>((String path) => path.replaceAllMapped(_escapeExpr, (Match match) => match.group(1)!).trim())
         .where((String path) => path.isNotEmpty)
     // The tool doesn't write duplicates to these lists. This call is an attempt to
     // be resilient to the outputs of other tools which write or user edits to depfiles.

packages/flutter_tools/test/general.shard/base/error_handling_io_test.dart

@@ -14,8 +14,6 @@ import 'package:flutter_tools/src/base/error_handling_io.dart';
 import 'package:flutter_tools/src/base/file_system.dart';
 import 'package:flutter_tools/src/base/io.dart';
 import 'package:flutter_tools/src/base/platform.dart';
-import 'package:flutter_tools/src/globals.dart' as globals show flutterUsage;
-import 'package:flutter_tools/src/reporting/reporting.dart';
 import 'package:mockito/mockito.dart';
 import 'package:path/path.dart' as path; // flutter_ignore: package_path_import
 import 'package:process/process.dart';
@@ -955,8 +953,7 @@ void main() {
       verify(source.copySync('dest')).called(1);
     });
 
-    // Uses context for analytics.
-    testUsingContext('copySync can directly copy bytes if both files can be opened but copySync fails', () {
+    testWithoutContext('copySync can directly copy bytes if both files can be opened but copySync fails', () {
       final MemoryFileSystem memoryFileSystem = MemoryFileSystem.test();
       final MockFile source = MockFile();
       final MockFile dest = MockFile();
@@ -978,15 +975,9 @@ void main() {
       fileSystem.file('source').copySync('dest');
 
       expect(memoryDest.readAsBytesSync(), expectedBytes);
-      expect((globals.flutterUsage as TestUsage).events, contains(
-        const TestUsageEvent('error-handling', 'copy-fallback'),
-      ));
-    }, overrides: <Type, Generator>{
-      Usage: () => TestUsage(),
     });
 
-    // Uses context for analytics.
-    testUsingContext('copySync deletes the result file if the fallback fails', () {
+    testWithoutContext('copySync deletes the result file if the fallback fails', () {
       final MemoryFileSystem memoryFileSystem = MemoryFileSystem.test();
       final MockFile source = MockFile();
       final MockFile dest = MockFile();
@@ -1015,8 +1006,6 @@ void main() {
       expect(() => fileSystem.file('source').copySync('dest'), throwsToolExit());
 
       verify(dest.deleteSync(recursive: true)).called(1);
-    }, overrides: <Type, Generator>{
-      Usage: () => TestUsage(),
     });
   });
 }