Mocha test subtask resolution in Hardhat 3

[BlockChain-Man]

Version of Hardhat

3.0.17

What happened?

No contracts to compile
Running Mocha tests
An unexpected error occurred:

Error [ERR_MODULE_NOT_FOUND]: Cannot find module 'H:\Blockchain\JS\hard\nodejs' imported from H:\Blockchain\JS\hard\node_modules\mocha\lib\nodejs\esm-utils.js
at finalizeResolution (node:internal/modules/esm/resolve:274:11)
at moduleResolve (node:internal/modules/esm/resolve:864:10)
at defaultResolve (node:internal/modules/esm/resolve:990:11)
at nextResolve (node:internal/modules/esm/hooks:785:28)
at resolveBase (file:///H:/Blockchain/js/hard/node_modules/tsx/dist/esm/index.mjs?1765132150489:2:3744)
at resolveDirectory (file:///H:/Blockchain/js/hard/node_modules/tsx/dist/esm/index.mjs?1765132150489:2:4243)
at resolveTsPaths (file:///H:/Blockchain/js/hard/node_modules/tsx/dist/esm/index.mjs?1765132150489:2 at resolve (file:///H:/Blockchain/js/hard/node_modules/tsx/dist/esm/index.mjs?1765132150489:2:5361)
at nextResolve (node:internal/modules/esm/hooks:785:28)
at AsyncLoaderHooksOnLoaderHookWorker.resolve (node:internal/modules/esm/hooks:271:30) {
code: 'ERR_MODULE_NOT_FOUND',
url: 'file:///H:/Blockchain/JS/hard/nodejs'
}

Minimal reproduction steps

npx hardhat test nodejs --coverage

Proposed solution

Resolve the parameter of the test task as follows:

npx hardhat test PARAM

• Process PARAM as a file (as implemented now) in case PARAM refers to a valid file path
• Resolve PARAM as a subtask in case it is not a valid file path
  • Throw the following error in case the subtask PARAM is not valid

    Error HHE416: Unrecognized subtask "PARAM" for the task "test"

[michalbrabec]

@BlockChain-Man there might be a confusion in the command syntax between the different test runners
The syntax for Mocha is

npx hardhat test mocha --coverage

The command help outlines this when you call

npx hardhat test --help

We should improve the error message for this case to avoid confusion.