How to use the @aws-cdk/aws-codebuild.BuildSpec.fromSourceFilename function in @aws-cdk/aws-codebuild

value: props.stageName
        },
        CROSS_ACCOUNT_ID: {
          type: BuildEnvironmentVariableType.PLAINTEXT,
          value: `${config.accountIds[props.stageName]}`
        },
        MAILOSAUR_API_KEY: {
          type: BuildEnvironmentVariableType.PARAMETER_STORE,
          value: '/test/mailosaur/apiKey'
        },
        MAILOSAUR_SERVER_ID: {
          type: BuildEnvironmentVariableType.PARAMETER_STORE,
          value: '/test/mailosaur/serverId'
        }
      },
      buildSpec: BuildSpec.fromSourceFilename('e2e-tests/buildspec.yml'),
      role,
      ...rest
    })
  }
}

value: props.stageName
        },
        CROSS_ACCOUNT_ID: {
          type: BuildEnvironmentVariableType.PLAINTEXT,
          value: `${config.accountIds[props.stageName]}`
        },
        MAILOSAUR_API_KEY: {
          type: BuildEnvironmentVariableType.PARAMETER_STORE,
          value: '/test/mailosaur/apiKey'
        },
        MAILOSAUR_SERVER_ID: {
          type: BuildEnvironmentVariableType.PARAMETER_STORE,
          value: '/test/mailosaur/serverId'
        }
      },
      buildSpec: BuildSpec.fromSourceFilename(
        'integration-tests/buildspec.yml'
      ),
      role,
      ...rest
    })
  }
}