fix: add missing 'index' to Gemini streaming tool calls and improve tests

jest.config.js

@@ -1,7 +1,7 @@
 export default {
   testEnvironment: 'node',
   transform: {
-    '^.+\\.js$': 'babel-jest',
+    '^.+\\.(js|mjs)$': 'babel-jest',
   },
   transformIgnorePatterns: [
     '/node_modules/(?!(uuid)/)', // uuid is an ESM module that needs to be transformed
@@ -15,8 +15,7 @@ export default {
     '^(\\.{1,2}/.*)\\.js$': '$1'
   },
   testMatch: [
-    '**/tests/api-server.test.js',
-    '**/tests/api-integration.test.js'
+    '**/tests/**/*.test.js'
   ],
   collectCoverageFrom: [
     'src/**/*.js',

src/converters/strategies/GeminiConverter.js

@@ -209,6 +209,7 @@ export class GeminiConverter extends BaseConverter {
                 }
                 if (part.functionCall) {
                     toolCalls.push({
+                        index: toolCalls.length,
                         id: part.functionCall.id || `call_${uuidv4()}`,
                         type: 'function',
                         function: {

tests/gemini-converter.test.js

@@ -0,0 +1,69 @@
+
+import GeminiConverter from '../src/converters/strategies/GeminiConverter.js';
+import { jest } from '@jest/globals';
+
+describe('GeminiConverter', () => {
+    let converter;
+
+    beforeEach(() => {
+        converter = new GeminiConverter();
+    });
+
+    test('toOpenAIStreamChunk adds index to tool_calls', () => {
+        const geminiChunk = {
+            candidates: [{
+                content: {
+                    parts: [{
+                        functionCall: {
+                            name: 'test_tool',
+                            args: { param: 'value' }
+                        }
+                    }]
+                }
+            }]
+        };
+
+        const result = converter.toOpenAIStreamChunk(geminiChunk, 'gemini-pro');
+
+        expect(result).not.toBeNull();
+        expect(result.choices[0].delta).toHaveProperty('tool_calls');
+        expect(result.choices[0].delta.tool_calls).toHaveLength(1);
+        expect(result.choices[0].delta.tool_calls[0]).toHaveProperty('index');
+        expect(result.choices[0].delta.tool_calls[0].index).toBe(0);
+        expect(result.choices[0].delta.tool_calls[0].function.name).toBe('test_tool');
+    });
+
+    test('toOpenAIStreamChunk handles multiple tool_calls with correct indices', () => {
+        const geminiChunk = {
+            candidates: [{
+                content: {
+                    parts: [
+                        {
+                            functionCall: {
+                                name: 'tool_one',
+                                args: {}
+                            }
+                        },
+                        {
+                            functionCall: {
+                                name: 'tool_two',
+                                args: {}
+                            }
+                        }
+                    ]
+                }
+            }]
+        };
+
+        const result = converter.toOpenAIStreamChunk(geminiChunk, 'gemini-pro');
+
+        expect(result).not.toBeNull();
+        expect(result.choices[0].delta.tool_calls).toHaveLength(2);
+        
+        expect(result.choices[0].delta.tool_calls[0].index).toBe(0);
+        expect(result.choices[0].delta.tool_calls[0].function.name).toBe('tool_one');
+
+        expect(result.choices[0].delta.tool_calls[1].index).toBe(1);
+        expect(result.choices[0].delta.tool_calls[1].function.name).toBe('tool_two');
+    });
+});