{"id":15370,"library":"redis-memory-server","title":"Redis Memory Server","description":"redis-memory-server is a utility that programmatically starts a real Redis server instance from Node.js, primarily designed for testing and development mocking. As of version 0.16.0, it provides an isolated, in-memory Redis environment for integration tests, allowing multiple instances to run concurrently on different ports. The package automatically handles downloading and compiling the `redis-server` binary, caching it for subsequent runs to improve performance. It is inspired by `mongodb-memory-server` and differentiates itself by providing a genuine Redis instance rather than a mock, ensuring high fidelity for integration testing. It supports Node.js environments version 18 and above, ships with TypeScript types, and abstracts away the complexities of managing Redis processes for testing workflows. Its release cadence appears active, with consistent updates for features and bug fixes.","status":"active","version":"0.16.0","language":"javascript","source_language":"en","source_url":"https://github.com/mhassan1/redis-memory-server","tags":["javascript","redis","mock","stub","redis-prebuilt","typescript"],"install":[{"cmd":"npm install redis-memory-server","lang":"bash","label":"npm"},{"cmd":"yarn add redis-memory-server","lang":"bash","label":"yarn"},{"cmd":"pnpm add redis-memory-server","lang":"bash","label":"pnpm"}],"dependencies":[],"imports":[{"note":"The package is primarily ESM-first for Node.js environments (>=18). While CommonJS `require` can be used, it might behave unexpectedly or require specific module configurations depending on your project setup. The class is a named export.","wrong":"const RedisMemoryServer = require('redis-memory-server')","symbol":"RedisMemoryServer","correct":"import { RedisMemoryServer } from 'redis-memory-server'"},{"note":"The main `RedisMemoryServer` class is a named export, not a default export. Attempting to import it as a default will result in an undefined value.","wrong":"import RedisMemoryServer from 'redis-memory-server'","symbol":"RedisMemoryServer","correct":"import { RedisMemoryServer } from 'redis-memory-server'"},{"note":"For type-only imports in TypeScript, use `import type` to ensure they are stripped during compilation and do not introduce runtime dependencies or accidental bundling of non-type code.","wrong":"import { RedisMemoryServerOpts } from 'redis-memory-server'","symbol":"RedisMemoryServerOpts","correct":"import type { RedisMemoryServerOpts } from 'redis-memory-server'"}],"quickstart":{"code":"import { RedisMemoryServer } from 'redis-memory-server';\nimport { Redis } from 'ioredis'; // ioredis is a common client, install it separately\n\nlet redisServer: RedisMemoryServer | undefined;\nlet redisClient: Redis | undefined;\n\nasync function runRedisTest() {\n  redisServer = new RedisMemoryServer({\n    binary: {\n      version: '6.2.6', // Specify a fixed version for deterministic builds\n    },\n  });\n\n  try {\n    const host = await redisServer.getHost();\n    const port = await redisServer.getPort();\n\n    console.log(`Redis server started on ${host}:${port}`);\n\n    redisClient = new Redis({\n      host,\n      port,\n    });\n\n    await redisClient.set('mykey', 'myvalue');\n    const value = await redisClient.get('mykey');\n    console.log(`Retrieved value: ${value}`); // Expected: 'myvalue'\n\n    await redisClient.del('mykey');\n    const deleted = await redisClient.get('mykey');\n    console.log(`Value after deletion: ${deleted}`); // Expected: null\n\n  } catch (error) {\n    console.error('An error occurred during the test:', error);\n  } finally {\n    if (redisClient) {\n      await redisClient.quit();\n      console.log('Redis client disconnected.');\n    }\n    if (redisServer) {\n      await redisServer.stop();\n      console.log('Redis memory server stopped.');\n    }\n  }\n}\n\nrunRedisTest();","lang":"typescript","description":"This quickstart demonstrates how to start a RedisMemoryServer instance, connect to it using ioredis, perform basic set/get operations, and ensure proper cleanup."},"warnings":[{"fix":"Ensure `make` is installed in your development and CI/CD environments. For faster CI, consider caching `node_modules/.cache/redis-binaries`.","message":"The initial installation or first run of `redis-memory-server` can be significantly slower than subsequent runs because it automatically downloads and compiles the `redis-server` binary. This process requires `make` to be available on your system.","severity":"gotcha","affected_versions":">=0.1.0"},{"fix":"Explicitly specify a fixed `version` in the `RedisMemoryServer` options (e.g., `{ binary: { version: '6.2.6' } }`) or use `REDISMS_IGNORE_DOWNLOAD_CACHE=true npm rebuild redis-memory-server` to force an update.","message":"By default, `redis-memory-server` downloads the 'stable' version of the Redis binary. After the first download, this binary is cached and will not be automatically updated, leading to less deterministic environments and potentially outdated or vulnerable Redis versions across different machines or builds.","severity":"gotcha","affected_versions":">=0.1.0"},{"fix":"Be aware of potential behavioral differences between Memurai and standard Redis. Plan for testing on Linux/macOS if specific Redis version behavior is critical.","message":"On Windows, this library uses Memurai instead of Redis. It is currently not possible to specify a particular version of Memurai or Redis when running on Windows.","severity":"gotcha","affected_versions":">=0.1.0"},{"fix":"Monitor memory usage in your test environment. Ensure `redisServer.stop()` is always called to release resources. Consider limiting parallel test runners in environments with constrained memory.","message":"Each `RedisMemoryServer` instance starts a full Redis server process, consuming approximately 4MB of memory. While suitable for isolated tests, running a very large number of parallel instances (e.g., hundreds) without careful resource management can lead to high memory consumption.","severity":"gotcha","affected_versions":">=0.1.0"}],"env_vars":null,"last_verified":"2026-04-21T00:00:00.000Z","next_check":"2026-07-20T00:00:00.000Z","problems":[{"fix":"Install `make` on your operating system. For Debian/Ubuntu: `sudo apt-get install build-essential`. For macOS: `xcode-select --install`.","cause":"The `make` utility is required for compiling the Redis binary but is missing from the system's PATH.","error":"Command failed with exit code 2: make"},{"fix":"Run `REDISMS_IGNORE_DOWNLOAD_CACHE=true npm rebuild redis-memory-server` to force a re-download and compilation. Ensure stable internet access and sufficient disk space.","cause":"The Redis binary could not be found or successfully downloaded/compiled, or the cache was invalidated without a rebuild.","error":"Error: Redis binary not found"},{"fix":"Always `await redisServer.getHost()` and `await redisServer.getPort()` to ensure the server is ready and you have the correct connection details. Ensure `redisServer.stop()` is called in a `finally` block or test teardown.","cause":"Your Redis client tried to connect to the RedisMemoryServer before it was fully started or after it was stopped, or with incorrect host/port details.","error":"connect ECONNREFUSED"}],"ecosystem":"npm"}