tests/migration/openai-stream.test.js

import test from 'node:test';
import assert from 'node:assert/strict';

import {
    convertAnthropicEventToOpenAIChunks,
    createOpenAIStreamState
} from '../../src/format/openai-stream.js';

test('Anthropic events become OpenAI chunks and a final usage chunk', () => {
    const state = createOpenAIStreamState('gemini-3.5-flash-low', true);
    const events = [
        {
            type: 'message_start',
            message: { id: 'msg_abc', usage: { input_tokens: 4 } }
        },
        {
            type: 'content_block_delta',
            index: 0,
            delta: { type: 'text_delta', text: 'Hi' }
        },
        {
            type: 'message_delta',
            delta: { stop_reason: 'end_turn' },
            usage: { output_tokens: 1 }
        },
        { type: 'message_stop' }
    ];

    const chunks = events.flatMap(event => convertAnthropicEventToOpenAIChunks(event, state));
    assert.equal(chunks[0].choices[0].delta.role, 'assistant');
    assert.equal(chunks[1].choices[0].delta.content, 'Hi');
    assert.equal(chunks[2].choices[0].finish_reason, 'stop');
    assert.equal(chunks[3].usage.total_tokens, 5);
});

test('tool deltas keep a stable OpenAI tool call index', () => {
    const state = createOpenAIStreamState('gemini-3.5-flash-low', false);
    convertAnthropicEventToOpenAIChunks({
        type: 'message_start',
        message: { id: 'msg_tool', usage: { input_tokens: 2 } }
    }, state);

    const start = convertAnthropicEventToOpenAIChunks({
        type: 'content_block_start',
        index: 3,
        content_block: { type: 'tool_use', id: 'call_1', name: 'lookup' }
    }, state);
    const delta = convertAnthropicEventToOpenAIChunks({
        type: 'content_block_delta',
        index: 3,
        delta: { type: 'input_json_delta', partial_json: '{"id":"1"}' }
    }, state);

    assert.equal(start[0].choices[0].delta.tool_calls[0].index, 0);
    assert.equal(delta[0].choices[0].delta.tool_calls[0].index, 0);
});