Release v51 breaks mdapi deployment

Summary

In release v51, force:mdapi:deploy now uses the REST API by default, which is failing with a JSON parser error. See below for error stack.

Steps To Reproduce:

1. Run the mdapi deployment without the --soapdeploy parameter

$ sfdx force:mdapi:deploy -u <env> -d <dir> --json -l RunSpecifiedTests -r skip

Expected result

Deployment is queued

Actual result

{
  "status": 1,
  "name": "Error",
  "message": "JSON_PARSER_ERROR: Can not deserialize: unexpected array at [line:1, column:73]",
  "exitCode": 1,
  "commandName": "MdapiDeployCommand",
  "stack": "Error: JSON_PARSER_ERROR: Can not deserialize: unexpected array at [line:1, column:73]\n    at Request._callback (/Users/alan.ly/.local/share/sfdx/client/7.88.4-3b2e55c3f1/node_modules/salesforce-alm/dist/lib/core/force.js:590:29)\n    at Request.self.callback (/Users/alan.ly/.local/share/sfdx/client/7.88.4-3b2e55c3f1/node_modules/request/request.js:185:22)\n    at Request.emit (events.js:315:20)\n    at Request.EventEmitter.emit (domain.js:467:12)\n    at Request.<anonymous> (/Users/alan.ly/.local/share/sfdx/client/7.88.4-3b2e55c3f1/node_modules/request/request.js:1154:10)\n    at Request.emit (events.js:315:20)\n    at Request.EventEmitter.emit (domain.js:467:12)\n    at IncomingMessage.<anonymous> (/Users/alan.ly/.local/share/sfdx/client/7.88.4-3b2e55c3f1/node_modules/request/request.js:1076:12)\n    at Object.onceWrapper (events.js:421:28)\n    at IncomingMessage.emit (events.js:327:22)\n    at IncomingMessage.EventEmitter.emit (domain.js:467:12)\n    at endReadableNT (internal/streams/readable.js:1327:12)\n    at processTicksAndRejections (internal/process/task_queues.js:80:21)\nOuter stack:\n    at Function.wrap (/Users/alan.ly/.local/share/sfdx/client/7.88.4-3b2e55c3f1/node_modules/@salesforce/core/lib/sfdxError.js:171:27)\n    at MdapiDeployCommand.catch (/Users/alan.ly/.local/share/sfdx/client/7.88.4-3b2e55c3f1/node_modules/salesforce-alm/dist/ToolbeltCommand.js:248:46)\n    at MdapiDeployCommand._run (/Users/alan.ly/.local/share/sfdx/client/7.88.4-3b2e55c3f1/node_modules/@salesforce/command/lib/sfdxCommand.js:85:13)\n    at Config.runCommand (/Users/alan.ly/.local/share/sfdx/client/7.88.4-3b2e55c3f1/node_modules/@oclif/config/lib/config.js:173:24)\n    at Main.run (/Users/alan.ly/.local/share/sfdx/client/7.88.4-3b2e55c3f1/node_modules/@oclif/command/lib/main.js:27:9)\n    at Main._run (/Users/alan.ly/.local/share/sfdx/client/7.88.4-3b2e55c3f1/node_modules/@oclif/command/lib/command.js:43:20)\n    at Object.run (/Users/alan.ly/.local/share/sfdx/client/7.88.4-3b2e55c3f1/dist/cli.js:121:21)",
  "warnings": []
}

Additional information

Feel free to attach a screenshot.

SFDX CLI Version(to find the version of the CLI engine run sfdx --version): Version 7.88.4 SFDX plugin Version(to find the version of the CLI plugin run sfdx plugins --core) Version 51.0.4 OS and version: macOS Catalina Version 10.15.7

[shetzel]

@aly76 - This specific error is due to the CLI sending the runTests property as a string but the REST API expects an array. That is an easy fix and we’ll let you know when it’s in latest-rc.

[azlam-abdulsalam]

The current workaround is to use --soapdeploy and everything works as expected