Introducing: How to Mock Outbound Http Calls for Easier Testing (2025 release wave 1)

Overview

The video explains why testing code that calls external services is hard: tests depend on the service being up, and running them against a live service can affect production. It introduces a new test Handler, the HTTP client Handler, which intercepts outbound HTTP requests during test execution so the test can return a mocked response instead.

The demo shows how to set up the Handler, attach it to a test with the Handler functions attribute, and use request properties to return different responses. It then covers the fall-through mechanism for mixing mocked and real calls, a live debugging session, and the test HTTP request policy that controls which outbound requests are allowed.

Key points

• Mark a procedure with the HTTP client Handler attribute and attach it to a test with the Handler functions attribute; all HTTP calls during that test are then routed to the Handler.
• The request object exposes request type, path, query parameters and a has-secret-URI property, which you can use to return different responses per request.
• When the request URI is set using secret text, path and query parameters are not available.
• Fall-through: the Handler returns a Boolean. Exit true issues the original request; exit false (the default) uses the mocked response, so an empty Handler still blocks the outbound call.
• Test HTTP request policy on a test codeunit has three options: allow all outbound requests (default), allow outbound only from the Handler, or block all outbound requests.
• Blocking outbound requests is suggested for automated CI/CD pipelines so tests never hit real endpoints.
• As of now, cookies and redirection status codes cannot be set in mocked responses.

Features

Every feature below: status not stated, demoed.

AL objects mentioned

As heard in the captions. A name that matches one object page by exact type and name links to it; the others stay as named.

• other “document service” at 1:46
• codeunit “test code unit” at 2:06
• other “response object” at 2:26
• other “request object” at 3:45

Not found in BC28-30: codeunit “test code unit”.

Quotes

• 0:04 “if we connect to the actual service we need to consider how that service will be impacted by running tests will it impact production”
• 1:25 “to address many of these challenges we have introduced a new test Handler in this release the HTTP client Handler”
• 2:06 “however this setup requires that the external service is up and running instead we can define an HTTP client hander to intercept the request”
• 4:21 “it is important to mention that as of now it is not possible to set cookies or redirection status codes so far so good”
• 5:16 “we have implemented a fall through mechanism that allows the programmer to decide in the Handler whether they want to Mark the response for”
• 5:53 “keep in mind that the default return value is false therefore a completely empty hander procedure would still block the outbound request and return”
• 8:31 “you can add it to test code units to specify how outbound request should be treated during test executions by default all requests are”

Disclaimers in the video

• 4:21 other: as of now it is not possible to set cookies or redirection status codes

Presenters (as heard): Stefan, Balash.