def METHOD_NAME(self, secret_specifier):
    c = {}
    from buildbot.config import BuilderConfig
    from buildbot.plugins import schedulers
    from buildbot.process.factory import BuildFactory
    c['schedulers'] = [
        schedulers.ForceScheduler(name="force", builderNames=["testy"])
    ]
    # note that as of August 2021, the vault docker image default to kv
    # version 2 to be enabled by default
    c['secretsProviders'] = [
        HashiCorpVaultKvSecretProvider(authenticator=VaultAuthenticatorToken('my_vaulttoken'),
                                       vault_server="http://localhost:8200",
                                       secrets_mount="secret")
    ]
    f = BuildFactory()
    f.addStep(ShellCommand(command=Interpolate(f'echo {secret_specifier} | base64')))
    c['builders'] = [
        BuilderConfig(name="testy",
                      workernames=["local1"],
                      factory=f)
    ]
    yield self.setup_master(c)