@dhensby Could you review this PR? 🙈

It appears that msnodesqlv8 does not support AD access tokens (TimelordUK/node-sqlserver-v8#83)

I note that this doesn't seem to be possible to pass in via a connection string (https://docs.microsoft.com/en-us/sql/connect/jdbc/connecting-using-azure-active-directory-authentication?view=sql-server-ver15). Is that your understanding too?

Exactly. Connection String does not contains any info about the access token. It's because should be generated dynamically, before the connection init, and passed as a separate parameter.

Here is a link to the interface of tedious connection config:
https://github.com/tediousjs/tedious/blob/master/src/connection.ts#L237

Please can we add tests for this, one to make sure the config is correctly constructed when passing a config object? It looks like we don't actually test this anywhere at the moment, which is a bit worrying...

I'll try to implement some unit tests for passing configurations.

@dhensby I cannot create unit tests for that. cfg constant is defined in _poolCreate scope, and there is no public access to that. I'm worried that only kind of integration tests could help, and there is no configuration for AD.

      const cfg = {
        server: this.config.server,
        options: Object.assign({
          encrypt: typeof this.config.encrypt === 'boolean' ? this.config.encrypt : true,
          trustServerCertificate: typeof this.config.trustServerCertificate === 'boolean' ? this.config.trustServerCertificate : false
        }, this.config.options),
        authentication: Object.assign({
          type: (
            (this.config.token !== undefined && 'azure-active-directory-access-token') ||
            (this.config.domain !== undefined && 'ntlm') ||
            'default'
          ),
          options: {
            userName: this.config.user,
            password: this.config.password,
            domain: this.config.domain,
            token: this.config.token
          }
        }, this.config.authentication)
      }

Anyway, I can see that the library accepts authentication parameter in the config model, so I guess that this PR isn't necessary to implement different authentication types for tedious. As I understood it correctly, it would be fine to pass something like this as the connection options:

const connectionPool = new ConnectionPoool({
  // ... other settings
  authentication: {
    type: 'azure-active-directory-access-token',
    options: {
      token: 'automatically-generated-token'
    }
  }
})

@funkydev - that's right, you can pass your own authentication object; so maybe we don't need this? But perhaps an update to the docs as an example of adding "custom auth" would be good?

@dhensby So I'm closing current PR, and creating new one: #1209 for documentation update.