Run JavaScript Js scripts in Zombienet tests and assert on the completeness or return value

Question

I saw this in Zombienet's Testing DSL page: https://github.com/paritytech/zombienet/blob/main/docs/src/test-dsl-definition-spec.md

Under Available Assertions

Custom js scripts: Allow to run a defined script and assert on the completeness or return value.

    node-name: js-script script_relative_path [ return is comparator target_value] [within x seconds]
        alice: js-script ./0008-custom.js return is greater than 1 within 200 seconds

How can I do that? My network file, z05-small-network.toml :

[relaychain]
default_image = "docker.io/parity/polkadot:{{POLKADOT_VERSION}}"
default_command = "polkadot"
default_args = [ "-lparachain=debug" ]
chain = "rococo-local"

  [[relaychain.nodes]]
  name = "alice"
  validator = true

  [[relaychain.nodes]]
  name = "bob"
  validator = true

[[parachains]]
id = 2000
cumulus_based = true

  [parachains.collator]
  name = "collator01"
  image = "{{COLLATOR_URL}}"
  command = "hero-collator"
  args = ["-lparachain=debug"]
  
[types.Header]
number = "u64"
parent_hash = "Hash"
post_state = "Hash"

My feature file:

Description: Small Network test
Network: ./z05-small-network.toml
Creds: config

# well know functions
alice: is up
bob: is up
alice: parachain 2000 is registered within 225 seconds

alice: js-script ./01-custom.js return is greater than 1 within 200 seconds

My Js file... 01-custom.js:

console.log("hello!!!");
return 2;

Then I got this error:

    ✔ alice: is up (147ms)
    ✔ bob: is up (88ms)
2022-08-24 18:46:43        API/INIT: Not decorating unknown runtime apis: 0xe5bdc752b8ec2ba1/1, 0x91a3c6922fd0a608/1, 0xb69782c4499462e5/1
    ✔ alice: parachain 2000 is registered within 225 seconds (2734ms)
hello!!!

     Error running script: ./01-custom.js
         undefined is not a function

    1) alice: js-script ./01-custom.js return is greater than 1 within 200 seconds

How can I assert on the completeness or return value?

Answer 1

thanks for your feedback! The custom js script must export a function call run that zombienet will call as part of the assertion.

You can check as example https://github.com/paritytech/zombienet/blob/main/tests/0008-custom.js

async function run(nodeName, networkInfo, args) {
    const {wsUri, userDefinedTypes} = networkInfo.nodesByName[nodeName];
    const api = await zombie.connect(wsUri, userDefinedTypes);
    const validator = await api.query.session.validators();
    return validator.length;
}

module.exports = { run }

I will also update the documentation to make notice of this requirement.

Thanks!