Debugging before Hooks in Mocha
Recently, I encountered an unusual issue while creating acceptance tests for a plugin. The before hook set up the
environment (e.g., database records, mocked dependencies), and the after hook cleaned up afterward. Running the test
individually worked fine, but it failed when run with other tests—it appeared that remnants of previous tests interfered
with the current test.
Under the debugger, the it blocks were skipped, and only the after hooks ran. Mocha’s behavior, as my AI assistant
explained, was perfectly reasonable: if the before hook fails, Mocha skips the it blocks but still executes the
after hooks.
After hours of refactoring and debugging, I couldn’t find any errors. Strangely, the problematic test worked fine when running all tests together but failed again during debugging. The hours spent debugging allowed me to frame the right question — one my AI assistant promptly answered with the perfect solution:
before(async function () {
this.timeout(60000); // 1 min
});The issue? Mocha’s default timeout for the before hook is 2 seconds. Debugging took longer than that, causing Mocha to
assume a failure. Setting the timeout explicitly resolved the issue immediately.
This is a reasonable default behavior for the framework, but knowing it beforehand could have saved me hours. Now I know — and so do you.