This article espouses what is known as "classicist testing" school of thought and rejects "mockist/London-style testing". I wholeheartedly agree with it. I have

This article espouses what is known as "classicist testing" school of thought and rejects "mockist/London-style testing". I wholeheartedly agree with it. I have been championing it in my team of 20+ devs since many years now, to great effect. You can read more about it in the excellent book by Vladimir Khorikov from January 2020 titled "Unit Testing Principles, Practices, and Patterns".