✨ Add logger config presets

src/presets.mbt

@@ -47,7 +47,10 @@ pub fn file(
   auto_flush~ : Bool = true,
   rotation~ : FileRotation? = None,
   text_formatter~ : TextFormatterConfig = default_text_formatter_config(),
-) -> LoggerConfig {
+) -> LoggerConfig raise ConfigError {
+  if path == "" {
+    raise ConfigError::InvalidConfig("File sink requires non-empty path")
+  }
   LoggerConfig::new(
     min_level=min_level,
     target=target,

src/presets_test.mbt

@@ -41,14 +41,22 @@ test "file preset uses file sink defaults" {
   inspect(config.queue is None, content="true")
 }
 
-test "file preset preserves empty path as configured" {
-  let config = file("")
-  inspect(match config.sink.kind {
-    SinkKind::File => "File"
-    _ => "other"
-  }, content="File")
-  inspect(config.sink.path, content="")
-  inspect(config.sink.rotation is None, content="true")
+test "file preset rejects empty path like parser file sink config" {
+  let preset_error = (fn() -> String raise ConfigError {
+    ignore(file(""))
+    "no error"
+  })() catch {
+    ConfigError::InvalidConfig(message) => message
+  }
+  inspect(preset_error, content="File sink requires non-empty path")
+
+  let parser_error = (fn() -> String raise ConfigError {
+    ignore(parse_logger_config_text("{\"sink\":{\"kind\":\"file\",\"path\":\"\"}}"))
+    "no error"
+  })() catch {
+    ConfigError::InvalidConfig(message) => message
+  }
+  inspect(parser_error, content="File sink requires non-empty path")
 }
 
 test "preset helpers compose queue and file rotation without losing config" {
@@ -94,6 +102,33 @@ test "preset helpers compose queue and file rotation without losing config" {
   }
 }
 
+test "queue helper preserves file rotation when applied after rotation" {
+  let config = with_queue(
+    with_file_rotation(file("service.log", append=false), 256, max_backups=2),
+    max_pending=8,
+    overflow=QueueOverflowPolicy::DropNewest,
+  )
+  inspect(config.sink.path, content="service.log")
+  inspect(config.sink.append, content="false")
+  match config.queue {
+    Some(queue) => {
+      inspect(queue.max_pending, content="8")
+      inspect(match queue.overflow {
+        QueueOverflowPolicy::DropNewest => "DropNewest"
+        QueueOverflowPolicy::DropOldest => "DropOldest"
+      }, content="DropNewest")
+    }
+    None => inspect(false, content="true")
+  }
+  match config.sink.rotation {
+    Some(rotation) => {
+      inspect(rotation.max_bytes, content="256")
+      inspect(rotation.max_backups, content="2")
+    }
+    None => inspect(false, content="true")
+  }
+}
+
 test "file rotation helper leaves non-file presets unchanged" {
   let console_config = with_file_rotation(console(target="console"), 64, max_backups=2)
   inspect(match console_config.sink.kind {
@@ -116,3 +151,29 @@ test "file rotation helper leaves non-file presets unchanged" {
   inspect(text_config.sink.text_formatter.separator, content=" :: ")
   inspect(text_config.sink.rotation is None, content="true")
 }
+
+test "file rotation helper keeps queued non-file presets unchanged" {
+  let config = with_queue(
+    json_console(min_level=Level::Error, target="json"),
+    max_pending=4,
+    overflow=QueueOverflowPolicy::DropOldest,
+  )
+  let rotated = with_file_rotation(config, 512, max_backups=5)
+  inspect(rotated.min_level.label(), content="ERROR")
+  inspect(rotated.target, content="json")
+  inspect(match rotated.sink.kind {
+    SinkKind::JsonConsole => "JsonConsole"
+    _ => "other"
+  }, content="JsonConsole")
+  inspect(rotated.sink.rotation is None, content="true")
+  match rotated.queue {
+    Some(queue) => {
+      inspect(queue.max_pending, content="4")
+      inspect(match queue.overflow {
+        QueueOverflowPolicy::DropNewest => "DropNewest"
+        QueueOverflowPolicy::DropOldest => "DropOldest"
+      }, content="DropOldest")
+    }
+    None => inspect(false, content="true")
+  }
+}