From 15 hours to 15 seconds: reducing a crushing build time

From 15 hours to 15 seconds: reducing a crushing build time

In summary:

• Bad Practice #1: We favoured integration tests over unit tests.
• Bad Practice #2: We had many, many features that were relatively unimportant.
• Bad Practice #3: Our integration tests were actually acceptance tests.
• Bonus tip: run the build entirely on the tmpfs in-memory file system.