The behavior of the request object (URLs, headers, body) being interpolated before the pre-request execution has caused several issues.

For example, consider the following scenario:

The request URL is:
http://localhost:8080/users?token={token}

And the pre-request script contains:

bru.setVar("token", "secret token");

In this case, if interpolation happens before the pre-request script is executed, the code in the script becomes ineffective, as the URL would already have been interpolated without the updated token value.

That said, I agree that there should be a way to enable request object interpolation ahead of time when needed. I’m considering introducing a bru.interpolate() API that can be invoked at the start of the script to address this requirement.

I find this to be an annoying limitation on an otherwise fantastic piece of software.

The above example seems contrived to me: why would you use a var in that case? I believe there are some cleaner options which don't require any assumptions about variable interpolation not having been performed yet.

So in order to make this contrived example work, Bruno is breaking my (IMO perfectly normal) use case for which I need interpolation to have been performed before my script is run:

• I'm using an API which requires me to sign the request. In my pre-request script, I'm calculating the signature which is based on URL+headers+body.
• My request uses an environment variable for the API's base URL, so the request's URL looks like {{base_url}}/some/path.
• Therefore, when I'm calculating the signature, I have to perform the variable interpolation on the URL myself.

As a workaround, I've implemented this function which returns the interpolated URL (using environment variables only, which is what I need, but I guess Bruno also allows other types of variables in the URL, so this function could be improved):

function getInterpolatedUrl() {
	const url = req.getUrl();
	const variableRegex = /\{\{([^\}]+)\}\}/g;
	return url.matchAll(variableRegex).reduce((transformedUrl, match) => transformedUrl.replaceAll("{{" + match[1] + "}}", bru.getEnvVar(match[1])), url);
}