Override empty stack traces for traced events (dart-archive/logging#158)

We already default to the current stack trace of the logging caller when
there is no stack trace available so the author has some signal for
where to look in the code.

Also default for non-null but empty stack traces. This is more useful
where an empty trace was passed through some signature to satisfy
nullability requirements and forwarded to the log.

Author: natebosch

pkgs/logging/CHANGELOG.md

@@ -1,5 +1,6 @@
-## 1.2.1-wip
+## 1.3.0-wip
 
+* Override empty stack traces for trace level events.
 * Require Dart 3.2
 
 ## 1.2.0

pkgs/logging/lib/src/logger.dart

@@ -202,6 +202,10 @@ class Logger {
   /// was made. This can be advantageous if a log listener wants to handler
   /// records of different zones differently (e.g. group log records by HTTP
   /// request if each HTTP request handler runs in it's own zone).
+  ///
+  /// If this record is logged at a level equal to or higher than
+  /// [recordStackTraceAtLevel] and [stackTrace] is `null` or [StackTrace.empty]
+  /// it will be defaulted to the current stack trace for this call.
   void log(Level logLevel, Object? message,
       [Object? error, StackTrace? stackTrace, Zone? zone]) {
     Object? object;
@@ -218,7 +222,8 @@ class Logger {
         object = message;
       }
 
-      if (stackTrace == null && logLevel >= recordStackTraceAtLevel) {
+      if ((stackTrace == null || stackTrace == StackTrace.empty) &&
+          logLevel >= recordStackTraceAtLevel) {
         stackTrace = StackTrace.current;
         error ??= 'autogenerated stack trace for $logLevel $msg';
       }

pkgs/logging/pubspec.yaml

@@ -1,5 +1,5 @@
 name: logging
-version: 1.2.1-wip
+version: 1.3.0-wip
 description: >-
   Provides APIs for debugging and error logging, similar to loggers in other
   languages, such as the Closure JS Logger and java.util.logging.Logger.

pkgs/logging/test/logging_test.dart

@@ -690,6 +690,22 @@ void main() {
       expect(records[2].stackTrace, isNull);
     });
 
+    test('defaults a missing trace', () {
+      final records = <LogRecord>[];
+      recordStackTraceAtLevel = Level.SEVERE;
+      root.onRecord.listen(records.add);
+      root.severe('hello');
+      expect(records.single.stackTrace, isNotNull);
+    });
+
+    test('defaults an empty trace', () {
+      final records = <LogRecord>[];
+      recordStackTraceAtLevel = Level.SEVERE;
+      root.onRecord.listen(records.add);
+      root.severe('hello', 'error', StackTrace.empty);
+      expect(records.single.stackTrace, isNot(StackTrace.empty));
+    });
+
     test('provided trace is used if given', () {
       final trace = StackTrace.current;
       final records = <LogRecord>[];