Verification and Validation

Verification

• When we check that application is created as per the SRS (software Requirement Specification). Means application performs what user wants it to do.
• It comes before validation.
• Static testing like reviews is verification process.

Validation

• When we test that application is performing its action in correct way. Here we do not check whether application meets user requirement or not, that part is already tested in verification. Here we test whatever application is doing, it does it in correct way.
• It is performed after verification.
• Test are executed in validation.

Let us go through one example - 

Requirement specification says that - 

User wants to control the lights in 4 rooms by remote command sent from the UI for each room separately.

Then functional specification is created as follows - 

1. The UI will contain 4 checkboxes labelled according to rooms they control.

2. When a checkbox is checked, the signal is sent to corresponding light. A green dot appears next to the checkbox.

3. When a checkbox is unchecked, the signal (turn off) is sent to corresponding light. A red dot appears next to the checkbox.

Verification

We now verify that  - 

• Requirement specification is complete and correct such that anyone can understand the requirement easily.
• Functional specification creates design correctly.
• Source code has functions for 4 checkboxes to send the signals.

Validation

Now we validate that - 

• Checkboxes accepts input from user 
• Lights are actually controlled by checkboxes.

Please let me know your views about the post.