HELM 3: Helm test is not working? Getting "TEST SUITE: None"

Preview: We started working on helm 3 to deploy our applications on k8s and we have come to good stage with deploying the charts successfully. However we are very new to implement tests under helm charts. For example I am deploying pdfreactor official image and i can check the web application version details either by using browser "https://ift.tt/2Y22UJl" or by "curl http://172.27.1.119:31423/service/". Now I want to write a helm test to check the same. The below is pdfreactor-test.yaml (reference link: https://helm.sh/docs/topics/chart_tests/)

apiVersion: v1
kind: Pod
metadata:
  name: "-credentials-test"
  annotations:
    "helm.sh/hook": test
spec:
  containers:
    - name: -credentials-test
      image: 
      imagePullPolicy: 
      command:
        - /bin/bash
        - curl http://172.27.1.119:31423/service/

When i ran

 helm install pdfreactor <chart name> 
 helm test pdfreactor 

I got below response

NAME: pdfreactor
LAST DEPLOYED: Thu Aug 13 09:02:55 2020
NAMESPACE: default
STATUS: deployed
REVISION: 1
TEST SUITE: None
NOTES:
Thank you for installing pdfreactor.

Below are my challenges.

1. Need to understand what am i doing wrong?
2. How exactly the helm test will work? Does it create a new pod and test, or does it test on existing pod?
3. What is the purpose of giving image details in test.yaml?

Note: I have even used the default template generated with helm create.