How do I fix the 'no implicit conversion of nil into String' error when creating a plan via API?

Context

You encounter errors like ‘no implicit conversion of nil into String’ or “undefined method `create_issue’ for nil” when creating a test plan and linking Jira issues via the Testomat.io Public API.

Answer

These errors are due to an invalid request structure.

Error 1: “no implicit conversion of nil into String” when creating a plan

• The request body format is invalid. Ensure the type and attributes structure matches the expected API format.
• Send a POST request to https://app.testomat.io/api/{project_id}/plans with this body:

  {
    "data": {
      "type": "plans",
      "attributes": {
        "title": "some title",
        "kind": "manual",
        "test-plan": "{\"tests\":[\"a760adbd\"]}"
      }
    }
  }

• Important: Do not include jira-issues in this request. Jira issues must be linked separately.

Error 2: “undefined method `create_issue’ for nil” when linking Jira issues

• This error usually indicates a missing or invalid parameter (plan_id, jira_id, jiraproject_id), incorrect Content-Type header, or a deleted or unrelated plan.

1. Confirm that the plan exists and belongs to the same project.
2. Use the endpoint POST https://app.testomat.io/api/{project_id}/jira/issues.
3. Send this request body:

   {
     "jira_id": "EP-2515",
     "plan_id": "71e04c51",
     "jiraproject_id": "d40a638c"
   }

4. Add the header Content-Type: application/json.
5. Verify that jira_id and jiraproject_id are valid and the plan_id is active and exists in the given project if the error persists.

Notes

• Use "type": "plans" and valid attributes when creating a plan.
• Attach Jira issues via the /jira/issues endpoint, never inside the plan-creation request.
• Always include Content-Type: application/json in the headers.
• Ensure all IDs exist and belong to the same project.