improve: tests

tests/ffmpeg.test.ts

@@ -1,5 +1,6 @@
 import { jest, describe, beforeEach, afterEach, it, expect } from '@jest/globals';
 import { spawn } from 'node:child_process';
+import type { ChildProcess } from 'node:child_process';
 
 import { FfmpegProcessError } from '../src';
 import { resolveFfmpegExecutable, startFfmpeg } from '../src/ffmpeg';
@@ -52,6 +53,26 @@ function createMockChildProcess(): MockChildProcess {
     };
 }
 
+function mockSpawnReturn(childProcess: MockChildProcess): void {
+    mockSpawn.mockReturnValue(childProcess as unknown as ChildProcess);
+}
+
+function getProcessHandler(childProcess: MockChildProcess, eventName: string): (...args: unknown[]) => void {
+    return childProcess.once.mock.calls.find(([event]) => event === eventName)?.[1] as (...args: unknown[]) => void;
+}
+
+function getStdoutHandler(childProcess: MockChildProcess, eventName: string): (...args: unknown[]) => void {
+    return childProcess.stdout.once.mock.calls.find(([event]) => event === eventName)?.[1] as (
+        ...args: unknown[]
+    ) => void;
+}
+
+function getStderrHandler(childProcess: MockChildProcess, eventName: string): (...args: unknown[]) => void {
+    return childProcess.stderr.on.mock.calls.find(([event]) => event === eventName)?.[1] as (
+        ...args: unknown[]
+    ) => void;
+}
+
 describe('ffmpeg helpers', () => {
     beforeEach(() => {
         jest.clearAllMocks();
@@ -72,7 +93,7 @@ describe('ffmpeg helpers', () => {
 
     it('spawns ffmpeg with the default argument set', () => {
         const childProcess = createMockChildProcess();
-        mockSpawn.mockReturnValue(childProcess);
+        mockSpawnReturn(childProcess);
 
         startFfmpeg('https://synradiode.stream.laut.fm/synradiode');
 
@@ -105,10 +126,10 @@ describe('ffmpeg helpers', () => {
 
     it('rejects readiness when ffmpeg startup emits an error', async () => {
         const childProcess = createMockChildProcess();
-        mockSpawn.mockReturnValue(childProcess);
+        mockSpawnReturn(childProcess);
 
         const handle = startFfmpeg('tests/audio.mp3');
-        const errorHandler = childProcess.once.mock.calls.find(([event]) => event === 'error')?.[1];
+        const errorHandler = getProcessHandler(childProcess, 'error');
 
         errorHandler(new Error('spawn ENOENT'));
 
@@ -118,11 +139,11 @@ describe('ffmpeg helpers', () => {
 
     it('includes stderr when ffmpeg exits before producing audio', async () => {
         const childProcess = createMockChildProcess();
-        mockSpawn.mockReturnValue(childProcess);
+        mockSpawnReturn(childProcess);
 
         const handle = startFfmpeg('tests/audio.mp3');
-        const stderrHandler = childProcess.stderr.on.mock.calls.find(([event]) => event === 'data')?.[1];
-        const exitHandler = childProcess.once.mock.calls.find(([event]) => event === 'exit')?.[1];
+        const stderrHandler = getStderrHandler(childProcess, 'data');
+        const exitHandler = getProcessHandler(childProcess, 'exit');
 
         stderrHandler('invalid input');
         exitHandler(1, null);
@@ -130,9 +151,37 @@ describe('ffmpeg helpers', () => {
         await expect(handle.ready).rejects.toThrow('invalid input');
     });
 
+    it('keeps the useful tail of long ffmpeg stderr output', async () => {
+        const childProcess = createMockChildProcess();
+        mockSpawnReturn(childProcess);
+
+        const handle = startFfmpeg('tests/audio.mp3');
+        const stderrHandler = getStderrHandler(childProcess, 'data');
+        const exitHandler = getProcessHandler(childProcess, 'exit');
+
+        stderrHandler(`${'x'.repeat(5_000)}final diagnostic`);
+        exitHandler(1, null);
+
+        await expect(handle.ready).rejects.toThrow('final diagnostic');
+    });
+
+    it('keeps readiness resolved when ffmpeg exits after producing audio', async () => {
+        const childProcess = createMockChildProcess();
+        mockSpawnReturn(childProcess);
+
+        const handle = startFfmpeg('tests/audio.mp3');
+        const readableHandler = getStdoutHandler(childProcess, 'readable');
+        const exitHandler = getProcessHandler(childProcess, 'exit');
+
+        readableHandler();
+        exitHandler(1, null);
+
+        await expect(handle.ready).resolves.toBeUndefined();
+    });
+
     it('uses custom executable and argument overrides when provided', () => {
         const childProcess = createMockChildProcess();
-        mockSpawn.mockReturnValue(childProcess);
+        mockSpawnReturn(childProcess);
 
         startFfmpeg('tests/audio.mp3', {
             executablePath: '/custom/ffmpeg',
@@ -150,7 +199,7 @@ describe('ffmpeg helpers', () => {
     it('stops a running child process and schedules a force kill fallback', () => {
         jest.useFakeTimers();
         const childProcess = createMockChildProcess();
-        mockSpawn.mockReturnValue(childProcess);
+        mockSpawnReturn(childProcess);
 
         const handle = startFfmpeg('tests/audio.mp3');
         handle.stop();
@@ -168,7 +217,7 @@ describe('ffmpeg helpers', () => {
     it('does not signal a process that already exited', () => {
         const childProcess = createMockChildProcess();
         childProcess.exitCode = 0;
-        mockSpawn.mockReturnValue(childProcess);
+        mockSpawnReturn(childProcess);
 
         const handle = startFfmpeg('tests/audio.mp3');
         handle.stop();