Merge pull request #164 from seek-oss/support-custom-log-levels

Add support for configuring custom log levels

.changeset/ninety-bobcats-return.md

@@ -0,0 +1,18 @@
+---
+'@seek/logger': minor
+---
+
+Add support for configuring custom log levels:
+
+```ts
+import createLogger from '@seek/logger';
+
+const logger = createLogger({
+  name: 'my-app',
+  customLevels: {
+    foo: 35,
+  },
+});
+
+logger.foo('Bar');
+```

src/index.test.ts

@@ -831,3 +831,53 @@ test('it merges serializers', async () => {
   expect(rootLog.headers).not.toHaveProperty('omit');
   expect(rootLog).not.toHaveProperty('req');
 });
+
+test('allows custom levels', async () => {
+  const stream = sink();
+  const logger = createLogger(
+    {
+      name: 'my-app',
+      customLevels: {
+        something: 35,
+      },
+    },
+    stream,
+  );
+
+  logger.something('foo');
+
+  const somethingLog: any = await once(stream, 'data');
+  expect(somethingLog.level).toBe(35);
+  expect(somethingLog.msg).toBe('foo');
+  expect(somethingLog.name).toBe('my-app');
+
+  logger.info('info');
+
+  const infoLog: any = await once(stream, 'data');
+  expect(infoLog.level).toBe(30);
+  expect(infoLog.msg).toBe('info');
+  expect(infoLog.name).toBe('my-app');
+});
+
+test('using custom levels does not leak into types or runtypes of other loggers', () => {
+  const stream = sink();
+
+  createLogger(
+    { name: 'custom-logger', customLevels: { something: 35 } },
+    stream,
+  );
+
+  const logger = createLogger({ name: 'my-app' }, stream);
+
+  expect(() => {
+    // @ts-expect-error - should not work
+    logger.something('foo');
+  }).toThrow();
+
+  logger.info('info');
+
+  const infoLog: any = stream.read();
+  expect(infoLog.level).toBe(30);
+  expect(infoLog.msg).toBe('info');
+  expect(infoLog.name).toBe('my-app');
+});

src/index.ts

@@ -12,21 +12,22 @@ export { DEFAULT_OMIT_HEADER_NAMES } from './serializers';
 
 export { pino };
 
-export type LoggerOptions = pino.LoggerOptions &
-  FormatterOptions &
-  SerializerOptions;
-export type Logger = pino.Logger;
+export type LoggerOptions<CustomLevels extends string = never> =
+  pino.LoggerOptions<CustomLevels> & FormatterOptions & SerializerOptions;
+
+export type Logger<CustomLevels extends string = never> =
+  pino.Logger<CustomLevels>;
 
 /**
  * Creates a logger that can enforce a strict logged object shape.
  * @param opts - Logger options.
  * @param destination - Destination stream. Default: `pino.destination({ sync: true })`.
  */
-export default (
-  opts: LoggerOptions = {},
+export default <CustomLevels extends string = never>(
+  opts: LoggerOptions<CustomLevels> = {},
   destination: pino.DestinationStream = createDestination({ mock: false })
     .destination,
-): Logger => {
+): Logger<CustomLevels> => {
   opts.redact = redact.addDefaultRedactPathStrings(opts.redact);
 
   const serializers = createSerializers(opts);