feat: expose x-trace-id in debug logs

Author: leoncheng57

CHANGELOG.md

@@ -7,6 +7,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 ## [Unreleased]
 ### Added
 <!-- * add to here... -->
+* Include `x-trace-id` response headers in debug logs
 ### Changed
 <!-- * add to here... -->
 

src/client.ts

@@ -227,14 +227,22 @@ export class HttpClient {
     ): Promise<{ statusCode: number; content: TContent }> {
         try {
             const response = await axiosInstance.request(axiosRequestConfig);
+            if (response.headers !== undefined) {
+                logDebug('Trace details:', {
+                    xTraceId: response.headers['x-trace-id'],
+                });
+            }
 
             if (axiosRequestConfig.responseType === 'text') {
                 // Workaround for axios-bug: https://github.com/axios/axios/issues/907
                 if (typeof response.data === 'object') {
                     response.data = JSON.stringify(response.data);
                 }
             }
-            return { statusCode: response.status, content: response.data };
+            return {
+                statusCode: response.status,
+                content: response.data,
+            };
         } catch (axios_error_raw) {
             const axiosError = axios_error_raw as AxiosError;
             const message: string = axiosError.message || '';

tests/client.test.ts

@@ -0,0 +1,64 @@
+// Copyright 2025 DeepL SE (https://www.deepl.com)
+// Use of this source code is governed by an MIT
+// license that can be found in the LICENSE file.
+
+import * as deepl from 'deepl-node';
+
+import { exampleText, makeDeeplClient, makeTranslator } from './core';
+import log from 'loglevel';
+
+jest.mock('loglevel', () => ({
+    debug: jest.fn(),
+    getLogger: jest.fn().mockReturnValue({
+        setLevel: jest.fn(),
+        debug: jest.fn(),
+        info: jest.fn(),
+    }),
+}));
+
+describe('client tests', () => {
+    describe('log debug', () => {
+        beforeEach(() => {
+            jest.clearAllMocks();
+            log.getLogger('deepl').setLevel('debug');
+        });
+
+        it('with translate text', async () => {
+            const translator = makeTranslator({});
+            const result = await translator.translateText(exampleText.en, null, 'de');
+
+            expect(log.getLogger('deepl').debug).toHaveBeenCalledTimes(3);
+            expect(log.getLogger('deepl').debug).toHaveBeenNthCalledWith(
+                1,
+                expect.stringContaining('Request details:'),
+            );
+            expect(log.getLogger('deepl').debug).toHaveBeenNthCalledWith(
+                2,
+                expect.stringContaining('Trace details:, xTraceId = '),
+            );
+            expect(log.getLogger('deepl').debug).toHaveBeenNthCalledWith(
+                3,
+                expect.stringContaining('Response details:, content = '),
+            );
+        });
+
+        it('with rephrase text', async () => {
+            const deeplClient = makeDeeplClient({});
+            const result = await deeplClient.rephraseText(exampleText.de, 'de');
+
+            expect(log.getLogger('deepl').debug).toHaveBeenCalledTimes(3);
+            expect(log.getLogger('deepl').debug).toHaveBeenNthCalledWith(
+                1,
+                expect.stringContaining('Request details:'),
+            );
+            expect(log.getLogger('deepl').debug).toHaveBeenNthCalledWith(
+                2,
+                expect.stringContaining('Trace details:, xTraceId = '),
+            );
+            expect(log.getLogger('deepl').debug).toHaveBeenNthCalledWith(
+                3,
+                expect.stringContaining('Response details:, content = '),
+            );
+        });
+    });
+});