MVC Test Automation:

Why Do Automated Testing?
Before digging into a testing approach, lets talk about key reasons to do automated testing:

• Rapid regression testing to allow systems/applications to continue to change and improve over time without long "testing" phases at the end of each development cycle
• Finding defects and problems earlier and faster especially when tests can be run on developer machines, and as part of a build on a CI server
• Ensure external integration points are working and continue to work as expected
• Ensure the user can interact with the system as expected
• Help debugging / writing / designing code
• Help specify the behaviour of the system

Overall, with automated testing we are aiming for increased project delivery speed with built in quality.
Levels of Automated Tests
Automated tests come in a variety of different flavours, with different costs and benefits. They are sometimes called by different names by different people. For the purposes of clarity, let's define the levels as follows:
Acceptance Tests
Highest level tests which treat the application as a black box. For an application with a user interface, they are tests which end up clicking buttons and entering text in fields. These tests are brittle (easily broken by intended user interface changes), give the most false negative breaks, expensive to write and expensive to maintain. But they can be written at a level of detail that is useful for business stakeholders to read, and are highly effective at ensuring the system is working from an end user perspective.
Integration Tests
Code which tests integration points for the system. They ensure that integration points are up and running, and that communication formats and channels are working as expected. Integration tests are generally fairly easy to write but maintenance can be time consuming when integration points are shared or under active development themselves. However, they are vital for ensuring that dependencies of the system you are building continue to work as you expect. These tests rarely give false negatives, run faster than acceptance tests but much slower than unit tests.
Unit Tests
Tests which are fine grained, extremely fast and test behaviour of a single class (or perhaps just a few related classes). They do not hit any external integration points. [This is not the most pure definition of unit tests, but for the purposes of this post, we do not need to break this category down further]. As unit tests are fast to write, easy to maintain (when they focus on behaviour rather than implementation) and run very quickly, they are effective for testing boundary conditions and all possible conditions and code branches.
Automated Test Strategy
An important part of test strategy is to decide the focus of each type of test and the testing mix. I'd generally recommend a testing mix with a majority of unit tests, some integration tests, and a small number of acceptance tests. In the test pyramid visualisation, I've included percentages of the number of tests, but this is just to give an idea of rough test mix breakdown.
So, why choose this sort of mix of tests? This mix allows you to cover alternative code paths and boundary conditions in tests that run very fast at the unit level. There are many combinations of these and they need to be easily maintained. Hence unit tests fit the bill nicely.
Integration tests are a slower and harder to maintain, so it's better to have less of them, and target them specifically to cover off the risks of system integration points. It would be inefficient to test your system logic with integration tests, since they would be slow, and you would not know if the failure was from your code or from the integration point.
Finally, acceptance tests are the most expensive tests to write, run and maintain. This is why it is important to minimise the number of these, and push down as much testing as possible to lower levels. They give a great view of "Is the System working?", but they are very inefficient for testing boundary conditions, all code paths etc. Generally, they are best for testing scenarios. For example, a scenario might be: Student logs in to the portal, chooses subjects for the semester in a multi-step wizard, then logs out. It would be best to avoid fine grained acceptance tests - they would cost more than the value they would add - ie, it would be better they had never been written. An example of such a test could be: Student chooses a subject and it is removed from the list of subjects available to be chosen. Or student enters an invalid subject code and is shown the error "Please choose a valid subject code". Both of these would be best pushed down to a unit test level. If this is not possible, it would be best to include them in a larger scenario to avoid the set up overhead (eg, for the error message test set up, it may be necessary to log in and enter data to get to step 3 of wizard before you can check if an invalid subject code error message is displayed).
With acceptance tests, I'd recommend writing the minimum up front, just covering the happy paths and a few major unhappy paths. If defects come to light from exploratory testing, then discover how they slipped through the testing net. Why weren't they covered by unit and integration tests, and could they be? If you have tried everything you can think of to improve lower levels of testing, and are still having too many defects creeping through, then consider upping your acceptance coverage. However, keep the cost/benefit analysis in mind. You want your tests to make your team go faster, and an overzealous acceptance suite can eat into the team's time significantly with maintenance and much increased cost of change. Finally, keep in mind there is a manual testing option. Manual testing needs to be minimised, but if it is 3 minutes to test something manually (eg, checking something shows up in a minor external system) or a week to automate the test, you're probably going to be better off keeping a manual test or two around.


Unit testing:

Unit testing using  NUNUIT or Junit framework

Integration testing with httpclient/rest assure
Other way is mocking the interface
Manual testing-http fiddler postman tools