feat: update fetch configuration logic

src/client.js

@@ -1,25 +1,11 @@
-let isNode = false;
-
 const VERSION = '0.0.3';
 const RETRY_STATUS_CODES = [429, 500, 502, 503, 504];
 const ENDPOINT = 'https://api.mistral.ai';
 
-/**
- * Initialize fetch
- * @return {Promise<void>}
- */
-async function initializeFetch() {
-  if (typeof window === 'undefined' ||
-    typeof globalThis.fetch === 'undefined') {
-    const nodeFetch = await import('node-fetch');
-    fetch = nodeFetch.default;
-    isNode = true;
-  } else {
-    fetch = globalThis.fetch;
-  }
-}
-
-initializeFetch();
+// We can't use a top level await if eventually this is to be converted
+// to typescript and compiled to commonjs, or similarly using babel.
+const configuredFetch = Promise.resolve(
+  globalThis.fetch ?? import('node-fetch').then((m) => m.default));
 
 /**
  * MistralAPIError
@@ -67,6 +53,17 @@ class MistralClient {
     }
   }
 
+  /**
+   * @return {Promise}
+   * @private
+   * @param {...*} args - fetch args
+   * hook point for non-global fetch override
+   */
+  async _fetch(...args) {
+    const fetchFunc = await configuredFetch;
+    return fetchFunc(...args);
+  }
+
   /**
    *
    * @param {*} method
@@ -90,11 +87,12 @@ class MistralClient {
 
     for (let attempts = 0; attempts < this.maxRetries; attempts++) {
       try {
-        const response = await fetch(url, options);
+        const response = await this._fetch(url, options);
 
         if (response.ok) {
           if (request?.stream) {
-            if (isNode) {
+            // When using node-fetch or test mocks, getReader is not defined
+            if (typeof response.body.getReader === 'undefined') {
               return response.body;
             } else {
               const reader = response.body.getReader();

tests/client.test.js

@@ -20,7 +20,7 @@ describe('Mistral Client', () => {
     it('should return a chat response object', async() => {
       // Mock the fetch function
       const mockResponse = mockChatResponsePayload();
-      globalThis.fetch = mockFetch(200, mockResponse);
+      client._fetch = mockFetch(200, mockResponse);
 
       const response = await client.chat({
         model: 'mistral-small',
@@ -37,7 +37,7 @@ describe('Mistral Client', () => {
     it('should return a chat response object if safeMode is set', async() => {
       // Mock the fetch function
       const mockResponse = mockChatResponsePayload();
-      globalThis.fetch = mockFetch(200, mockResponse);
+      client._fetch = mockFetch(200, mockResponse);
 
       const response = await client.chat({
         model: 'mistral-small',
@@ -55,7 +55,7 @@ describe('Mistral Client', () => {
     it('should return a chat response object if safePrompt is set', async() => {
       // Mock the fetch function
       const mockResponse = mockChatResponsePayload();
-      globalThis.fetch = mockFetch(200, mockResponse);
+      client._fetch = mockFetch(200, mockResponse);
 
       const response = await client.chat({
         model: 'mistral-small',
@@ -75,7 +75,7 @@ describe('Mistral Client', () => {
     it('should return parsed, streamed response', async() => {
       // Mock the fetch function
       const mockResponse = mockChatResponseStreamingPayload();
-      globalThis.fetch = mockFetchStream(200, mockResponse);
+      client._fetch = mockFetchStream(200, mockResponse);
 
       const response = await client.chatStream({
         model: 'mistral-small',
@@ -98,7 +98,7 @@ describe('Mistral Client', () => {
     it('should return parsed, streamed response with safeMode', async() => {
       // Mock the fetch function
       const mockResponse = mockChatResponseStreamingPayload();
-      globalThis.fetch = mockFetchStream(200, mockResponse);
+      client._fetch = mockFetchStream(200, mockResponse);
 
       const response = await client.chatStream({
         model: 'mistral-small',
@@ -122,7 +122,7 @@ describe('Mistral Client', () => {
     it('should return parsed, streamed response with safePrompt', async() => {
       // Mock the fetch function
       const mockResponse = mockChatResponseStreamingPayload();
-      globalThis.fetch = mockFetchStream(200, mockResponse);
+      client._fetch = mockFetchStream(200, mockResponse);
 
       const response = await client.chatStream({
         model: 'mistral-small',
@@ -148,7 +148,7 @@ describe('Mistral Client', () => {
     it('should return embeddings', async() => {
       // Mock the fetch function
       const mockResponse = mockEmbeddingResponsePayload();
-      globalThis.fetch = mockFetch(200, mockResponse);
+      client._fetch = mockFetch(200, mockResponse);
 
       const response = await client.embeddings(mockEmbeddingRequest);
       expect(response).toEqual(mockResponse);
@@ -159,7 +159,7 @@ describe('Mistral Client', () => {
     it('should return batched embeddings', async() => {
       // Mock the fetch function
       const mockResponse = mockEmbeddingResponsePayload(10);
-      globalThis.fetch = mockFetch(200, mockResponse);
+      client._fetch = mockFetch(200, mockResponse);
 
       const response = await client.embeddings(mockEmbeddingRequest);
       expect(response).toEqual(mockResponse);
@@ -170,7 +170,7 @@ describe('Mistral Client', () => {
     it('should return a list of models', async() => {
       // Mock the fetch function
       const mockResponse = mockListModels();
-      globalThis.fetch = mockFetch(200, mockResponse);
+      client._fetch = mockFetch(200, mockResponse);
 
       const response = await client.listModels();
       expect(response).toEqual(mockResponse);