casefile-runner helps you test CLI-style behavior using a single .case.yaml file that contains:

• CLI args
• Virtual input files
• Expected stdout and/or stderr

npm install casefile-runner

args:
  - input/a.txt
input/a.txt: |
  hello
stdout: |
  hello
stderr: |
  warning: demo stderr line

import { executeCasefileFile } from 'casefile-runner';

const result = await executeCasefileFile('example.case.yaml', async (files, args) => {
  const fileMap = new Map(files.map((item) => [item.path, item.content]));
  const content = fileMap.get(args[0] ?? '') ?? '';

  return {
    stdout: content,
    stderr: 'warning: demo stderr line\n',
    exitCode: 0
  };
});

• parseCasefile(source) parses raw YAML fixture text.
• loadCasefile(path) reads and parses a fixture file from disk.
• runCasefile(testCase, executor) runs an already-parsed case.
• executeCasefileFile(path, executor, options) reads, runs, and optionally updates expected output.

Pass updateExpected: true to rewrite stdout/stderr sections from actual output:

await executeCasefileFile(casePath, executor, { updateExpected: true });