Coding, Testing: Which is First?

I saw some managers planning that Resource-A will do the coding and Resource-B will do the Unit testing. In my opinion it is totally a misconception about the unit testing. Unit testing is not a task to complete. It is integral part of coding. Unit testing without coding and coding without unit testing both are not productive. In a test driven environment, we need to design and plan our work so that after coding few lines, write test cases and verify the code just we completed.

I noticed some people coding and directly testing from UI. In this approach unit tests gets lower priority in front of the anxiety to do the final testing using UI. Unit tests just considered as a distraction and additional work. This leads to a poor quality of code. More time spent on debugging during development and testing. Writing unit tests after coding increases development time and there is a more tendency that not able to cover all important cases. Again it leads to a poor quality of code. Bottom line is, if we don’t do it in a right way, adding more time can not improve the quality.

It is important to understand the reasons for the below questions
Why people tend to do the integration testing before unit testing?
How it matters unit testing after complete coding instead of testing while coding?

Some times people not sure about what they are coding and not sure weather it is going to work together with the rest of the system or not. So they will focus directly on integration testing. This is true because at the end if they find this solution is not going to work, it need to throw out all the code along with the unit tests. Instead of trying to do the coding work it is required to do some design home work. Some times adding an integration test with the stubs and discussing with the peers about the solution helps to improve the situation.

My answer to the second question is it definitely matters the way we write the unit tests. We can apply a generic principle, If the delay in getting feedback increased, its effectiveness will be decreased. I mean executing unit tests is something like getting feedback from the code. We can write good tests cases for the code written in few minutes compared to the code written in last week or last month. Also it takes more time to recollect and understand the code. Taking immediate feedback saves time in debugging during integration.