The error returned from the mock GRPC call is not interpreted as an error

[maqiuyujoyce]

Describe your question

In the mock test, the error returned from the mock GRPC call is not interpreted as an error (- was want and + was got):

        -       "error": {
        -         "code": 404,
        -         "message": "Resource 'projects/${projectId}/locations/global/entitlements/privilegedaccessmanagerentitlement-${uniqueId}' was not found",
        -         "status": "NOT_FOUND"
        -       }
        +       "code": 5,
        +       "details": [],
        +       "message": "Resource 'projects/${projectId}/locations/global/entitlements/privilegedaccessmanagerentitlement-${uniqueId}' was not found"
              }

[maqiuyujoyce]

Root cause:

The mock service handler was registered with the real ServeMux instead of the mockgcp ServeMux. Example fix can be found here.