If you've recently updated phpstorm, you may have noticed autocompletion for phpunit assertions aren't showing up! This is by design, the desired effect was to limit the auto completion list. However, if you're like me and rely on this list for writing your tests, then you're not alone. A youtrack issue was opened and as to their usual awesome customer support JetBrains has provided the answer.

When the auto completion dialog appears simply hit Ctrl + Space. This will show the complete list of methods. If you hit twice, you'll see static methods as well.