The article emits a key point, when talking about any practice: the context, in which unit testing is performed. The size of the team, the type of company, the technology, and the impact of product defects.
For a startup with a small team and few customers building an MVP? Unit testing is overrated.
For a company with 50 engineers in 10 teams building a product, that moved $500,000/day in revenue? Unit testing could or could not be overrated.
For a company with 1,000 engineers working in the same repo, shipping a product that moves $50M in revenue per day? Unit testing is most likely underrated - and essential.
You cannot ignore how the organization works, and the cost of a defect that a unit test could have caught. I happen to work at the third type of organization, and while unit tests might not be the most efficient type of safety net, it is a very big one. We have other types of testing layers on top of unit: integration and E2E tests as well.
Also, one more fallacy in the article:
"If we look back, it’s clear that high-level testing was tough in 2000, it probably still was in 2009, but it’s 2020 outside and we are, in fact, living in the future. Advancements in technology and software design have made it a much less significant issue than it once was."
This is not true everywhere. High-level / E2E testing on native mobile applications in 2020 is just as bad as it was on the web in 2009.
> Unit testing is most likely underrated - and essential.
You are right, but it still doesn't mean aiming for high coverage. In the big company case you'll want to cover the interfaces and dependencies and less of your team's code.
I know that part of this will fall under "integration" but definitions are sneaky.
For a startup with a small team and few customers building an MVP? Unit testing is overrated.
For a company with 50 engineers in 10 teams building a product, that moved $500,000/day in revenue? Unit testing could or could not be overrated.
For a company with 1,000 engineers working in the same repo, shipping a product that moves $50M in revenue per day? Unit testing is most likely underrated - and essential.
You cannot ignore how the organization works, and the cost of a defect that a unit test could have caught. I happen to work at the third type of organization, and while unit tests might not be the most efficient type of safety net, it is a very big one. We have other types of testing layers on top of unit: integration and E2E tests as well.
Also, one more fallacy in the article: "If we look back, it’s clear that high-level testing was tough in 2000, it probably still was in 2009, but it’s 2020 outside and we are, in fact, living in the future. Advancements in technology and software design have made it a much less significant issue than it once was."
This is not true everywhere. High-level / E2E testing on native mobile applications in 2020 is just as bad as it was on the web in 2009.