Cannot find module 'fs-extra' when testing with Truffle

Question

I am reading the tutorial on Ethereum Pet Shop -- Your First DApp, everything seems ok until I test with truffle test with below error:

Error: Cannot find module 'fs-extra'
at Function.Module._resolveFilename (internal/modules/cjs/loader.js:636:15)
at Function.Module._load (internal/modules/cjs/loader.js:562:25)
at Module.require (internal/modules/cjs/loader.js:690:17)
at require (internal/modules/cjs/helpers.js:25:18)
at Object.call (/Users/.npm-global/lib/node_modules/truffle/node_modules/@truffle/debugger/dist/external "fs-extra":1:18)
at r (/Users/.npm-global/lib/node_modules/truffle/node_modules/@truffle/debugger/dist/webpack/bootstrap:19:22)
[...]
Truffle v5.2.4 (core: 5.2.4)
Node v10.16.0

I have tried some suggestions as in Module is extraneous npm, but the Error: Cannot find module 'fs-extra' insists.

Answer 1

You need to add it to your package.json and install the package.

1. Either run

   npm install --save fs-extra
   

   The --save option will add it to the package.json for you.

2. Or add it manually to the package.json section dependencies

   "dependencies": {
       "fs-extra": "^9.1.0"
   }
   

   and then install it

   npm install
   

   Version 9.1.0 is the current version according to npmjs