Continuous Integration? Soooo ooold, so ninetees. Not hot anymore, not trendy. Currently even Continuous Delivery sounds like something regular, typical, borig. Everybody does CI... or do they?
In order to answer this question, let's refer to the excellent article, published by Martin Fowler
here. Headline states:
Continuous Integration is a software development practice where members of a team integrate their work frequently (...). Each integration is verified by an automated build (including test) to detect integration errors as quickly as possible.
That's it.
Code (yes, this includes tests!)
Commit.
Pull/push (
integrate).
Let something (a CI server for instance)
run tests and confirm that everything is in order
Four easy steps. However, the devil is in the detail.
First of all, the steps should be executed at least once a day, preferably multiple times a day by each team member. This way, any integration issues will be discovered on the spot. If your team has a habit of keeping
private branches for a long time, without source integration and pushes (triggering a full CI build), well, you're
not doing CI! If you use feature branches, which are a good thing, keep them public, so that CI server can watch them during development time.
Second of all,
tests are the cornerstone of CI. Usually not all tests are run during build - in order to make it faster, only quick, small unit ones. If project build isn't fast, developers won't build before pushing changes (we're all always super busy, aren't we?). Therefore all expensive tests - especially integration ones - should be left for CI server. It's a general rule for a bigger builds. This way if an issue fits into this 1% not covered by unit tests, it should be found by the end of the day. By the way it's really a good habit to have a
blame mails enabled in the CI server. The name is a bit misleading - it's not about the blame, it's all about fixing broken build (or bad tests!) as soon as possible.
All of what was above can be found in the aforementioned Martin Fowler's article - in a more elaborate way. Yes, it's a quite old one, but still very, very relevant.
