Moves the default level from the logger constructor to the filter getter, mitigates #38

Author: Bungeefan

lib/src/log_filter.dart

@@ -7,7 +7,12 @@ import 'logger.dart';
 /// You can implement your own `LogFilter` or use [DevelopmentFilter].
 /// Every implementation should consider [Logger.level].
 abstract class LogFilter {
-  Level? level;
+  Level? _level;
+
+  // Still nullable for backwards compatibility.
+  Level? get level => _level ?? Logger.level;
+
+  set level(Level? value) => _level = value;
 
   Future<void> init() async {}
 

lib/src/logger.dart

@@ -51,7 +51,9 @@ class Logger {
         _printer = printer ?? defaultPrinter(),
         _output = output ?? defaultOutput() {
     _filter.init();
-    _filter.level = level ?? Logger.level;
+    if (level != null) {
+      _filter.level = level;
+    }
     _printer.init();
     _output.init();
   }

test/logger_test.dart

@@ -36,6 +36,17 @@ class _CallbackPrinter extends LogPrinter {
   }
 }
 
+/// Test class for the lazy-initialization of variables.
+class LazyLogger {
+  static bool? printed;
+  static final filter = ProductionFilter();
+  static final printer = _CallbackPrinter((l, m, e, s) {
+    printed = true;
+    return [];
+  });
+  static final logger = Logger(filter: filter, printer: printer);
+}
+
 void main() {
   Level? printedLevel;
   dynamic printedMessage;
@@ -194,10 +205,33 @@ void main() {
     expect(printedMessage, 'This is');
   });
 
+  test('Setting filter Levels', () {
+    var filter = ProductionFilter();
+    expect(filter.level, Logger.level);
+
+    final initLevel = Level.warning;
+    var logger = Logger(
+      filter: filter,
+      printer: callbackPrinter,
+      level: initLevel,
+    );
+    expect(filter.level, initLevel);
+
+    filter.level = Level.fatal;
+    expect(filter.level, Level.fatal);
+  });
+
   test('Logger.close', () async {
     var logger = Logger();
     expect(logger.isClosed(), false);
     await logger.close();
     expect(logger.isClosed(), true);
   });
+
+  test('Lazy Logger Initialization', () {
+    expect(LazyLogger.printed, isNull);
+    LazyLogger.filter.level = Level.warning;
+    LazyLogger.logger.i("This is an info message and should not show");
+    expect(LazyLogger.printed, isNull);
+  });
 }