Skip test file unless explicitly targeted. This allows an "unfriendly" test file to live along other test files and not interfere "run all tests".

isThisTestFileRunExplicitly.js

/**
  * This test file should only be run explicitly. When that's the case, the command should look something like:
  *   npm run test ./some/test/folder/test-something.js
  * which means the process arguments should be something like:
  *   [ "some/path/node", "some/path/mocha", "./some/test/folder/test-something.js" ]
  * but we can not assume the third argument would always be a file path.
  * So to evaluate this flag, the function should:
  * 1. Check if argv[2] is likely a file path pointing at this file.
  * 2. resolve argv[2] and compare with this file's absolute path.
  */
const isThisTestFileRunExplicitly = (() => {
     const possibleFilePath = process.argv[2];
     // Should at least have 3 arguments.
     if (!possibleFilePath) {
         return false;
     }
     // Possible file path should end with this file name.
     if (!(
         // The test target may not have an extension.
         possibleFilePath.endsWith(path.extname(__filename))
             // Compare with extension.
             ? possibleFilePath.endsWith(`/${path.basename(__filename)}`)
             // Compare without extension.
             : possibleFilePath.endsWith(`/${path.basename(__filename, path.extname(__filename))}`)
     )) {
         return false;
     }

     const normalizedFilePathWithExtname = path.normalize(
         possibleFilePath.endsWith(path.extname(__filename))
             ? possibleFilePath
             // : possibleFilePath, // Replace the line below with this line to test this flag by setting it to false when an extension is not specified.
             : `${possibleFilePath}${path.extname(__filename)}`,
     );
     const absoluteFilePath = path.isAbsolute(normalizedFilePathWithExtname)
         ? normalizedFilePathWithExtname
         : path.resolve(process.cwd(), normalizedFilePathWithExtname);

     return absoluteFilePath === __filename;
 })();

(isThisTestFileRunExplicitly ? describe : describe.skip)("module being tested", function() {
    // ...
});