Scripting & assertions

Each request can carry a Pre-request and a Post-response script (the Scripts tab). They run JavaScript via the goja engine — pure Go, no Node. The pre script runs before the request is built (and can mutate it); the post script runs after the response is read.

The canonical use is logging in once and forwarding a token:

// Post-response hook on a Login request
helena.env.set("TOKEN", response.json.token);

{{TOKEN}} is then available in any later request for the lifetime of the process. The session overlay never touches disk.

The helena.* API

Call	What it does
helena.env.get(name) / set(name, value)	Read / write the session env overlay (writes never persist). helena.vars.get is an alias for get.
helena.interpolate(template)	Resolve {{vars}} in a string with the same scope chain a send uses; reflects helena.env.set made earlier in the same script.
helena.sendRequest({url, method, headers, body})	Fire an ad-hoc HTTP request through the host client (same cookie jar) and get a response object back (status, json, headers, …).
helena.cookies.get(url, name) / getAll(url)	Read the cookie jar for a URL.
helena.runner.stop() / skip()	In a headless helena run, halt the run or skip the current request's send.
helena.uuid()	A random RFC 4122 v4 UUID.
helena.hash.md5 / sha1 / sha256 / sha512(text) and hmacSha1 / hmacSha256(key, text)	Hex digests.
helena.base64.encode / decode(s)	Standard base64.
helena.date.now() / timestamp()	ISO-8601 string / Unix seconds.
helena.sleep(ms)	Delay the script (bounded by the script timeout, cancellable).
console.log / info / warn / error(...)	Append to the Scripts console.

The pre-request script also gets a mutable request (method, url, body, headers, params); the post-response script gets a read-only request plus response (status, headers, body, json, xml).

Tests & assertions

Two complementary ways to check a response:

Scripted — test() / expect() inside a script:

test("status is 200", function () {
  expect(response.status).toBe(200);
  expect(response.json.id).toBeDefined();
});

Matchers include toBe, toEqual, toBeTruthy/toBeFalsy, toBeNull, toBeDefined/toBeUndefined, toContain, toHaveLength, toBeGreaterThan/toBeLessThan, each negatable via .not.

Declarative — the no-code Assertions tab: rows of source · operator · expected (e.g. res.status equals 200) evaluated after each send.

Both surface their pass/fail results in the Scripts console and in helena run reports.

Chaining

A request's Chain tab lists other requests to run first, each bound to an alias. Their results are available to this request's scripts and templates as chain.<alias>.response.… — so you can authenticate, then use the token, in one Send. See the User guide for a worked example.