Programming Phoenix

Isolating Wolfram

We’d like to keep our Wolfram tests isolated, but we have a problem. Our code makes an HTTP request to the WolframAlpha API, which isn’t something we want to perform within our test suite. You might be thinking, “Let’s write a bunch of mocks!”

Within the Elixir community, we want to avoid mocking whenever possible. Most mocking libraries, including dynamic stubbing libraries, end up changing global behavior—for example, by replacing a function in the HTTP client library to return some particular result. These function replacements are global, so a change in one place would change all code running at the same time. That means tests written in this way can no longer run concurrently. These kinds of strategies can snowball, requiring ...