Add tests for callback

tests/outputs/callback.spec.ts

@@ -0,0 +1,56 @@
+import { expect, test } from "@playwright/test";
+import { Logger } from "../../src/Logger";
+import Callback from "../../src/outputs/Callback";
+import { LogContext, LogLevel, LogMeta } from "../../src/types/logger";
+
+test("Constructor", () => {
+  const _callbackOutput = new Callback({
+    enabled: true,
+    callback(_message, _meta, _context) {
+      return;
+    },
+  });
+});
+
+test("Log Messages", () => {
+  let logMessages: string[] = [];
+  let logMetas: LogMeta[] = [];
+  let logContexts: LogContext[] = [];
+
+  const callbackOutput = new Callback({
+    enabled: true,
+    callback(message, meta, context) {
+      logMessages.push(message);
+      logMetas.push(meta);
+      logContexts.push(context);
+    },
+  });
+
+  const logger = new Logger().addOutput(callbackOutput);
+
+  logger.log("logging a", 10, {});
+
+  logger.trace("logging b");
+  logger.debug("logging c");
+  logger.info("logging d");
+  logger.warn("logging e");
+  logger.fatal("logging f");
+
+  expect(logMetas[0].level).toBe(LogLevel.TRACE);
+  expect(logMessages[0]).toBe("logging a");
+
+  expect(logMetas[1].level).toBe(LogLevel.TRACE);
+  expect(logMessages[1]).toBe("logging b");
+
+  expect(logMetas[2].level).toBe(LogLevel.DEBUG);
+  expect(logMessages[2]).toBe("logging c");
+
+  expect(logMetas[3].level).toBe(LogLevel.INFO);
+  expect(logMessages[3]).toBe("logging d");
+
+  expect(logMetas[4].level).toBe(LogLevel.WARN);
+  expect(logMessages[4]).toBe("logging e");
+
+  expect(logMetas[5].level).toBe(LogLevel.FATAL);
+  expect(logMessages[5]).toBe("logging f");
+});