Karate global function is undefined exception

Unable to call appendGlobalHeaders from scenario, getting org.graalvm.polyglot.PolyglotException: ReferenceError: "appendGlobalHeaders" is not defined

In karate-config.js:

karate.configure('headers', {
  'Content-Type': 'application/json',
  'Authorization': 'Bearer <your-token>'
});

function appendGlobalHeaders(headers) {
  var globalHeaders = karate.get('headers');
  return karate.append(headers, globalHeaders);
}

In Karate test file:

Feature: Append Global Headers to Request Headers

  Scenario: Make an API request with appended headers
    Given url 'https://api.example.com/users'
    * def requestHeaders = appendGlobalHeaders({ 'X-Custom-Header': 'Custom-Value' })
    When method GET
    Then status 200

You have not implemented karate-config.js correctly or understood Karate variables. I also think you should try a different approach.

Why don't you try this in karate-config.js (this is the complete code):

function fn() {
  var headersFn = function() {
    var headers = { 
      'Content-Type': 'application/json',
      'Authorization': 'Bearer <my-token>',
      'Extra-Header': karate.get('myVariable')
    };
    return headers;
  };
  karate.configure('headers', headersFn);
}

And in your feature you can do this:

* def myVariable = 'foo'
* url 'https://httpbin.org/get'
* method get

Try it and see how it works.

And one good thing is that if a value is null, Karate won't set that header. You can use that to your dynamic advantage. Note that you can conditionally add headers with if-then conditions as explained in the documentation.

Maybe instead of all this complexity, you may choose to just go with a simple approach where each Scenario sets headers using the header or headers keyword and you don't use configure at all. That's perfectly fine and up to you.

Another approach you could try is something like this:

* headers genHeaders('X-Custom-Header', 'Custom-Value')

So all you need to do is define a function in scope called genHeaders that returns a JSON.