Depending on the value you set in buildtemplate.yaml for the OW_RUNTIME_PLATFORM parameter, you will need to invoke different endpoints to execute the test.
curl -H "Host: nodejs-web-action-helloworld.default.example.com" -X POST http://localhost/ <html><body><h3>hello Joe</h3></body></html>
You have an option to initialize the runtime with the function and other configuration data if its not initialized (i.e. built using build-without-code.yaml.tmpl)
curl -H "Host: nodejs-web-action-helloworld.default.example.com" -d "@knative-data-init.json" -H "Content-Type: application/json" http://localhost/
{"OK":true}
Execute the function.
curl -H "Host: nodejs-web-action-helloworld.default.example.com" -d "@knative-data-run.json" -H "Content-Type: application/json" -X POST http://localhost/ <html><body><h3>hello Joe</h3></body></html>
Initialize the runtime with the function and other configuration data using the /init endpoint.
curl -H "Host: nodejs-web-aciton-helloworld.default.example.com" -d "@openwhisk-data-init.json" -H "Content-Type: application/json" http://localhost/init
{"OK":true}
Execute the function using the /run endpoint.
curl -H "Host: nodejs-web-action-helloworld.default.example.com" -d "@openwhisk-data-run.json" -H "Content-Type: application/json" -X POST http://localhost/run <html><body><h3>hello Joe</h3></body></html>