I'm having a different problem. Typescript does have NodeGit.Cred.sshKeyMemoryNew for me but no NodeGit.Credential. Trying to use NodeGit.Cred.sshKeyMemoryNew doesn't work in Node 14 or 16 when using "nodegit": "^0.28.0-alpha.21" and "@types/nodegit": "^0.28.2". If I change to sshKeyNew I get the same deprecation warning, but it works. I've been trying different builds of nodegit 0.28.0 alphas for a while and have yet to find one that works on sskKeyMemoryNew. The same code does work in "nodegit": "^0.27.0"

Trying to use NodeGit.Cred.sshKeyMemoryNew simply throws the error Method clone has thrown an error. with no additional info (or fetch or other calls). Trying to call it directly looks like it's been removed.

import { Cred } from "nodegit";

const credentials = await Cred.sshKeyMemoryNew("git", deployKeyPublic, deployKeyPrivate, "");

throws:
TypeError: nodegit_1.Cred.sshKeyMemoryNew is not a function

So it looks like sshKeyMemoryNew has been removed from the new version but is still in the typings and docs. Looking at https://github.com/nodegit/nodegit/blob/master/lib/credential.js seems to concur.

Edit: More digging, it looks like the deprecated Cred doesn't have sshKeyMemoryNew but Credential does.

{
    "typeof NodeGit.Cred": "object",
    "typeof NodeGit.Credential": "function",
    "Object.keys(NodeGit.Cred)": [
      "defaultNew",
      "sshKeyFromAgent",
      "sshKeyNew",
      "usernameNew",
      "userpassPlaintextNew",
      "TYPE"
    ],
    "Object.keys(NodeGit.Credential)": [
      "defaultNew",
      "sshKeyFromAgent",
      "sshKeyMemoryNew",
      "sshKeyNew",
      "usernameNew",
      "userpassPlaintextNew",
      "getSelfFreeingInstanceCount",
      "getNonSelfFreeingConstructedCount",
      "TYPE"
    ]
  }

So there's two bugs. One is here in nodegit that sshKeyMemoryNew is missing from credential.js. The second is in DefinitelyTyped that it's missing NodeGit.Credential.

@nakky Upgrade @types/nodegit to ^0.28.3 to fix Typescript using NodeGit.Credential.sshKeyMemoryNew(). #1973 will fix NodeGit.Cred.sshKeyMemoryNew().

@tkmcmaster I agree with you. When I was looking inside, it seemed that the namespace of the js library had been changed, but Typescript did not support it. (I used "@types/nodegit": "^0.28.2")
Thanks for the update!! After updating to ^0.28.3 and rewriting to Credential, it worked! !