[package_info] Migrate to null safety (flutter#3398)

Author: bparrishMines

packages/package_info/CHANGELOG.md

@@ -1,3 +1,7 @@
+## 0.5.0-nullsafety
+
+* Migrate to null safety.
+
 ## 0.4.3+4
 
 * Ensure `IntegrationTestPlugin` is registered in `example` app, so Firebase Test Lab tests report test results correctly. [Issue](https://github.com/flutter/flutter/issues/74944).

packages/package_info/lib/package_info.dart

@@ -24,30 +24,31 @@ class PackageInfo {
   /// See [fromPlatform] for the right API to get a [PackageInfo] that's
   /// actually populated with real data.
   PackageInfo({
-    this.appName,
-    this.packageName,
-    this.version,
-    this.buildNumber,
+    required this.appName,
+    required this.packageName,
+    required this.version,
+    required this.buildNumber,
   });
 
-  static PackageInfo _fromPlatform;
+  static PackageInfo? _fromPlatform;
 
   /// Retrieves package information from the platform.
   /// The result is cached.
   static Future<PackageInfo> fromPlatform() async {
-    if (_fromPlatform != null) {
-      return _fromPlatform;
-    }
+    PackageInfo? packageInfo = _fromPlatform;
+    if (packageInfo != null) return packageInfo;
 
     final Map<String, dynamic> map =
-        await _kChannel.invokeMapMethod<String, dynamic>('getAll');
-    _fromPlatform = PackageInfo(
+        (await _kChannel.invokeMapMethod<String, dynamic>('getAll'))!;
+
+    packageInfo = PackageInfo(
       appName: map["appName"],
       packageName: map["packageName"],
       version: map["version"],
       buildNumber: map["buildNumber"],
     );
-    return _fromPlatform;
+    _fromPlatform = packageInfo;
+    return packageInfo;
   }
 
   /// The app name. `CFBundleDisplayName` on iOS, `application/label` on Android.

packages/package_info/pubspec.yaml

@@ -5,7 +5,7 @@ homepage: https://github.com/flutter/plugins/tree/master/packages/package_info
 # 0.4.y+z is compatible with 1.0.0, if you land a breaking change bump
 # the version to 2.0.0.
 # See more details: https://github.com/flutter/flutter/wiki/Package-migration-to-1.0.0
-version: 0.4.3+4
+version: 0.5.0-nullsafety
 
 flutter:
   plugin:
@@ -29,8 +29,8 @@ dev_dependencies:
     sdk: flutter
   integration_test:
     path: ../integration_test
-  pedantic: ^1.8.0
+  pedantic: ^1.10.0-nullsafety
 
 environment:
-  sdk: ">=2.1.0 <3.0.0"
+  sdk: ">=2.12.0-0 <3.0.0"
   flutter: ">=1.12.13+hotfix.5"

packages/package_info/test/package_info_test.dart

@@ -11,7 +11,7 @@ void main() {
 
   const MethodChannel channel =
       MethodChannel('plugins.flutter.io/package_info');
-  List<MethodCall> log;
+  late List<MethodCall> log;
 
   channel.setMockMethodCallHandler((MethodCall methodCall) async {
     log.add(methodCall);

script/nnbd_plugins.sh

@@ -15,6 +15,7 @@ readonly NNBD_PLUGINS_LIST=(
   "google_sign_in"
   "local_auth"
   "path_provider"
+  "package_info"
   "plugin_platform_interface"
   "share"
   "shared_preferences"