fix(instrumentation-pino): Propagate all args to mixin

We noticed that our user-defined `mixin` was breaking because it could
not access the third `logger` argument.

https://getpino.io/#/docs/api?id=mixin-function

Author: 72636c

packages/instrumentation-pino/src/instrumentation.ts

@@ -67,10 +67,14 @@ export class PinoInstrumentation extends InstrumentationBase<PinoInstrumentation
           if (origMixin === undefined) {
             logger[mixinSym] = otelMixin;
           } else {
-            logger[mixinSym] = (ctx: object, level: number) => {
+            logger[mixinSym] = (
+              ctx: object,
+              level: number,
+              ...rest: unknown[]
+            ) => {
               return Object.assign(
                 otelMixin(ctx, level),
-                origMixin(ctx, level)
+                origMixin(ctx, level, ...rest)
               );
             };
           }

packages/instrumentation-pino/test/pino.test.ts

@@ -371,6 +371,48 @@ describe('PinoInstrumentation', () => {
       });
     });
 
+    it('propagates parameters to user mixin', () => {
+      const logger = pino(
+        {
+          name: 'LogLog',
+          mixin: (mergeObject: object, level: number, logger: Pino.Logger) => ({
+            mixinArgs: {
+              mergeObject,
+              level,
+              logger: {
+                bindings: logger.bindings(),
+              },
+            },
+            mixinProp: 'mixinValue',
+          }),
+        },
+        process.stdout
+      );
+
+      const childLogger = logger.child({ childProp: 'childValue' });
+
+      tracer.startActiveSpan('abc', span => {
+        childLogger.info({ objProp: 'objValue' }, 'a message');
+        span.end();
+
+        const record = JSON.parse(stdoutSpy.firstCall.args[0].toString());
+        assertRecord(record, span);
+        assert.deepStrictEqual(record['mixinArgs'], {
+          mergeObject: {
+            objProp: 'objValue',
+          },
+          level: 30,
+          logger: {
+            bindings: {
+              childProp: 'childValue',
+            },
+          },
+        });
+        assert.strictEqual(record['mixinProp'], 'mixinValue');
+        assert.strictEqual(record['name'], 'LogLog');
+      });
+    });
+
     it('ensures user mixin values take precedence', () => {
       const logger = pino(
         {