Mastering React Test-Driven Development

Backtracking on ourselves

There's only one piece of shared state that our tests use and that's document. It must not be getting cleared each time the tests are run, and so we see the output of each test inside the document.

Even if we fixed our production code to remove the hard-coding, it still wouldn't pass; instead, we'd see the text AshleyJordan.

One solution is to clear the document DOM tree before each test run. But there's a simpler solution: we can rework our tests to not append our container element to the DOM at all, and instead work directly with the container element. In other words, we can change our expectation to check not document.body.textContent but container.textContent.

There may come a time that we actually need to attach ...