Rewrite the last_ping key again (#255)

* Rewrite the `last_ping` key again

* Apply test fix from #247

* Use timestamp instead of null

* Format fix

* Update version

* Code review comments

* Lingering comment

pkgs/unified_analytics/CHANGELOG.md

@@ -1,3 +1,7 @@
+## 5.8.7
+
+- [Bug fix](https://github.com/dart-lang/tools/issues/252) to rewrite the `last_ping` key into the session json file
+
 ## 5.8.6
 
 - Refactored session handler class to use the last modified timestamp as the last ping value

pkgs/unified_analytics/lib/src/constants.dart

@@ -82,7 +82,7 @@ const int kLogFileLength = 2500;
 const String kLogFileName = 'dart-flutter-telemetry.log';
 
 /// The current version of the package, should be in line with pubspec version.
-const String kPackageVersion = '5.8.6';
+const String kPackageVersion = '5.8.7';
 
 /// The minimum length for a session.
 const int kSessionDurationMinutes = 30;

pkgs/unified_analytics/lib/src/initializer.dart

@@ -84,8 +84,12 @@ class Initializer {
   }) {
     final now = sessionIdOverride ?? clock.now();
     sessionFile.createSync(recursive: true);
+
+    // `last_ping` has been deprecated, remains included for backward
+    // compatibility
     sessionFile
-        .writeAsStringSync('{"session_id": ${now.millisecondsSinceEpoch}}');
+        .writeAsStringSync('{"session_id": ${now.millisecondsSinceEpoch}, '
+            '"last_ping": ${now.millisecondsSinceEpoch}}');
   }
 
   /// This will check that there is a client ID populated in

pkgs/unified_analytics/pubspec.yaml

@@ -4,7 +4,7 @@ description: >-
   to Google Analytics.
 # When updating this, keep the version consistent with the changelog and the
 # value in lib/src/constants.dart.
-version: 5.8.6
+version: 5.8.7
 repository: https://github.com/dart-lang/tools/tree/main/pkgs/unified_analytics
 
 environment:

pkgs/unified_analytics/test/unified_analytics_test.dart

@@ -143,7 +143,8 @@ void main() {
       final timestamp = clock.now().millisecondsSinceEpoch.toString();
       expect(sessionFile.readAsStringSync(), 'contents');
       analytics.userProperty.preparePayload();
-      expect(sessionFile.readAsStringSync(), '{"session_id": $timestamp}');
+      expect(sessionFile.readAsStringSync(),
+          '{"session_id": $timestamp, "last_ping": $timestamp}');
 
       // Attempting to fetch the session id when malformed should also
       // send an error event while parsing
@@ -199,7 +200,8 @@ void main() {
       final timestamp = clock.now().millisecondsSinceEpoch.toString();
       expect(sessionFile.existsSync(), false);
       analytics.userProperty.preparePayload();
-      expect(sessionFile.readAsStringSync(), '{"session_id": $timestamp}');
+      expect(sessionFile.readAsStringSync(),
+          '{"session_id": $timestamp, "last_ping": $timestamp}');
 
       // Attempting to fetch the session id when malformed should also
       // send an error event while parsing
@@ -1031,6 +1033,14 @@ ${initialTool.label}=$dateStamp,$toolsMessageVersion
 
   test('Null values for flutter parameters is reflected properly in log file',
       () {
+    // Because we are using the `MemoryFileSystem.test` constructor,
+    // we don't have a real clock in the filesystem, and because we
+    // are checking the last modified timestamp for the session file
+    // to determine if we need to update the session id, manually setting
+    // that timestamp will ensure we are not updating session id when it
+    // first gets created
+    sessionFile.setLastModifiedSync(DateTime.now());
+
     // Use a for loop two initialize the second analytics instance
     // twice to account for no events being sent on the first instance
     // run for a given tool