Jest custom transformer - can its performance be improved?

Question

I am testing the performance of a custom transformer using Jest. Currently, the transformer does nothing but return the code it receives from Jest. The transformer has implemented a function getCacheKey.

Here is the whole code for the transformer:

function process(src, path, config, transformOptions) {
  return src;
}
exports.process = process;

function getCacheKey(fileData, filePath, configStr, options) {
  return crypto.createHash('md5')
    .update(fileData + filePath + configStr, 'utf8')
    .digest('hex');
}
exports.getCacheKey = getCacheKey;

Transformer Link

Jest's configuration is package.jsonas follows:

"jest": {
  "transform": {
    "^.+\\.tsx?$": "<rootDir>/ts-transformer.js"
  },
  "testMatch": [
    "<rootDir>/test-jest/**/*.ts"
  ],
  "moduleFileExtensions": [
    "ts",
    "tsx",
    "js",
    "json"
  ]
}

Link to package.json

When testing this setup with Jest, it takes the same amount of time with and without --no-cache(about 9 seconds)

When testing this setup with Mocha, the first run takes about 7 seconds, and subsequent runs about 4 seconds.

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Answer 1

, (fileData, filePath, configStr) , .

function getCacheKey(fileData, filePath, configStr, options) {
    const hash = crypto.createHash('md5');
    hash.update(fileData);
    hash.update(filePath);
    hash.update(configStr);
    return hash.digest('hex');
}

. , , "utf8".