Should I unit test my /src files or /build files?

Question

When setting up unit tests (in my case, using Jasmine for JavaScript) should the un-minified/in-uglified src files be tested? Or should the end-user build files (minified and uglified) be tested?

In my grunt config:

jasmine: {
    src: ['src/file.js']
}

vs.

jasmine: {
    src: ['build/file.min.js']
}

On one hand, it's nice to test the src files since it doesn't remove debuggers and is easier to inspect when needed.

On the other hand, I can test the src files as much as I like but it's not true to what the end users will be running, as the build files are uglified and minified.

Answer 1

You should definitely unit test the bare source files as there were written. Unit tests are designed to be tightly focused and give you instant and clear feedback . In other words, if you test your functionality after the source code being modified - you are not testing your code in isolation; once you discover a bug, you cannot be 100% sure what caused it - it could be that there was a problem during the build that caused the problem - say the uglify task.

I would classify testing build files as a part of integration or a higher-level testing - since aside from testing functionality, you are also checking how your application was built: how the files were minified, copied, concatenated etc.

In general, you should aim to the following pyramid:

( introduced in this Google Test Automation blogpost )

On the other hand, I can test the src files as much as I like but it's not true to what the end users will be running, as the build files are uglified and minified.

I think this goes under the End-to-end testing category - imitating a real user, going through acceptance-testing scenarios, user stories.