Encoding not recognized in jest.js

Question

I have a problem testing a project using node-mysql2, react, sequelize and jest. This problem only occurs during testing.

Encoding not recognized: 'cesu8' (searched as: 'cesu8')
    at Object.getCodec (project/node_modules/mysql2/node_modules/iconv-lite/lib/index.js:106:23)
    at Object.getDecoder (project/node_modules/mysql2/node_modules/iconv-lite/lib/index.js:122:23)
    at Object.<anonymous>.exports.decode (project/node_modules/mysql2/lib/parsers/string.js:9:23)
    at Packet.Object.<anonymous>.Packet.readNullTerminatedString (project/node_modules/mysql2/lib/packets/packet.js:373:23)
    at Function.Object.<anonymous>.Handshake.fromPacket (project/node_modules/mysql2/lib/packets/handshake.js:18:31)
    at ClientHandshake.Object.<anonymous>.ClientHandshake.handshakeInit (project/node_modules/mysql2/lib/commands/client_handshake.js:98:38)
    at ClientHandshake.Object.<anonymous>.Command.execute (project/node_modules/mysql2/lib/commands/command.js:40:20)
    at Connection.Object.<anonymous>.Connection.handlePacket (project/node_modules/mysql2/lib/connection.js:515:28)
    at PacketParser.onPacket (project/node_modules/mysql2/lib/connection.js:94:16)
    at PacketParser.executeStart (project/node_modules/mysql2/lib/packet_parser.js:77:14)
    at Socket.<anonymous> (project/node_modules/mysql2/lib/connection.js:102:29)

Answer 1

This is problem caused by mysql2 doing dynamic lazy require of encodings and Jest not being able to handle this. Have a look at few workarounds users suggested here:

add this snippet to setupTestFrameworkScriptFile

require('mysql2/node_modules/iconv-lite').encodingExists('foo');

or this somewhere early to your code:

import iconv from 'iconv-lite';
import encodings from 'iconv-lite/encodings';
iconv.encodings = encodings;

Answer 2

I met a similar issue with network node module. I made a workaround by mocking the network module and not using the iconv-lite. The following is my code.

jest.mock('network', () => ({
  get_active_interface: cb => {
    cb?.(undefined, { type: 'Wired' });
  },
}));

As for this case, maybe you could try mock the module that made the call, some code like this.

jest.mock('mysql2',()=>({
    someFuncThatCallsIcoveLite:(..._)=>{} 
}))

Answer 3

Really only need to add:

require('iconv-lite').encodingExists('foo')

to the top of whatever file you're testing such as factory.test.js

Not sure why this is unfortunately, but the above is better for copy / pasting than the chosen answer.

Answer 4

require('../../node_modules/mysql2/node_modules/iconv-lite/lib').encodingExists('foo');

This worked for me on

• Node 16.17.1
• ts 4.8.4
• jest 29.2.2

Answer 5

In my case, the encoding error appeared after a ReferenceError

The cause was a test calling a method that was making an async database call via mysql2 for which I had forgotten to await.

The solution for me was to simply add await in the right place.

ReferenceError: You are trying to `import` a file after the Jest environment has been torn down. From models/alert.test.js.

      at Object.getCodec (node_modules/mysql2/node_modules/iconv-lite/lib/index.js:63:27)
      at Object.getDecoder (node_modules/mysql2/node_modules/iconv-lite/lib/index.js:125:23)
      at Object.<anonymous>.exports.decode (node_modules/mysql2/lib/parsers/string.js:10:25)
      at Packet.readNullTerminatedString (node_modules/mysql2/lib/packets/packet.js:412:25)
      at Function.fromPacket (node_modules/mysql2/lib/packets/handshake.js:62:33)                ^
...
Error: Encoding not recognized: 'cesu8' (searched as: 'cesu8')
    at Object.getCodec (/Users/.../node_modules/mysql2/node_modules/iconv-lite/lib/index.js:104:23)