  { run: mustCall(function(msg) {
      const { server } = setup(
        this,
        { username: USER,
          privateKey: CLIENT_KEY_RSA_RAW
        },
        { hostKeys: [HOST_KEY_RSA] }
      );

      server.on('connection', mustCall((conn) => {
        let authAttempt = 0;
        conn.on('authentication', mustCall((ctx) => {
          switch (++authAttempt) {
            case 1:
              assert(ctx.method === 'none'),
                     msg(`Wrong auth method: ${ctx.method}`);
              return ctx.reject();
            case 3:
              assert(ctx.signature, msg('Missing publickey signature'));
            // FALLTHROUGH
            case 2:
              assert(ctx.method === 'publickey',
                     msg(`Wrong auth method: ${ctx.method}`));
              assert(ctx.username === USER,
                     msg(`Unexpected username: ${ctx.username}`));
              assert(ctx.key.algo === 'ssh-rsa',
                     msg(`Unexpected key algo: ${ctx.key.algo}`));
              assert.deepEqual(CLIENT_KEY_RSA.getPublicSSH(),
                               ctx.key.data,
                               msg('Public key mismatch'));
              break;
          }
          if (ctx.signature) {
            assert(CLIENT_KEY_RSA.verify(ctx.blob, ctx.signature) === true,
                   msg('Could not verify PK signature'));
          }
          ctx.accept();
        }, 3)).on('ready', mustCall(() => {
          conn.end();
        }));
      }));
    }),
The software constructs all or part of an OS command using externally-influenced input from an upstream component, but it does not neutralize or incorrectly neutralizes special elements that could modify the intended OS command when it is sent to a downstream component.