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3. Test Strategy
In order to develop high quality software, thorough testing is essential.
This document is a high level presentation of the test approach to be undertaken in relation to Twitter Sentiment Visualisation.
This is a process where the tests are written before the code is developed. The test cases are written based on the user stories, and most the logic on the application is developed in the tests, so when it comes to writing the code it should be a very quick process.
TDD was chosen as the testing methodology, as it has several key advantages. Firstly it will ensure the code that is written is structured, as the structure must be determined before the code can be written. Secondly it helps the code fit with the user stories, since the tests will be based from the user stories. It also creates a detailed specification. Most importantly less time is spend debugging and fixing bugs, as code is written to pass tests.
Unit testing involves writing a series of very thorough tests to cover each module, function or method independently as a unit. Each function should be checked that it produces the expected output with a variety of hardcoded inputs. This should include testing error handling, and borderline and unexpected inputs. After the unit tests have been written the unit test process can be automated, so every time a method is changed, the tests are rerun to check that it still produces the correct output with various inputs.
Unit testing has a lot of benefits to software development, firstly any potential bugs or failures will be identified before that function gets integrated with the larger application. Developers can verify their code still works as expected as they refractor and change parts, in the same way, unit testing can prevent future changes from breaking functionality. It also helps you understand your code, and gives you instant feedback when something is not working as it should be.
This is the same principle as TDD, but involves writing tests with a more functional point of view. The syntax used to write the tests tends to be more like English, and the tests follow very closely to the user stories. Following BDD will ensure that the code written follows user stories, so as long as they are complete, then the finished solution should also be thorough.
| Test Type | Pass Condition |
|---|---|
| Functional Testing | All acceptance criteria must be met, checked and documented |
| Unit Tests | 100% of unit tests must pass. It will be immediately clear when a unit test is failing |
| Integration Tests | 100% pass rate after every commit |
| Coverage Tests | 80% or greater |
| Code Reviews | B grade/ Level 4 or higher. Ideally A grade/ Level 5 if possible. |
| Dependency Checks | Mostly up-to-date dependencies except in justified circumstances. |
A ststus of all unit tests, coverage tests, dependency checks and code review will be displayed in the form of badges on the repository readme. Each will be linked with the appropriate service, so will update live. This will indicate immediately as soon as a test is failing or a dependency becomes outdated.
Detailed test reports for each testing method will also be generated and saved.
Framework – Mocha
Mocha is a feature-rich and well established JavaScript testing framework. A JavaScript framework is required in order to store, write and run the tests in a structured way. Using a framework will also make using various testing plugins easier to use neatly.
Assertion Library – Chai
An assertion library will provide structure and syntax in order to actually write the test cases. Chai is a good choice, as it fits nicely with Mocha, and has a very flexible syntax, including a ‘should’ library built in, which will allow for tests to be written in a BDD style.
Coverage Testing – Istanbul
Coverage testing measures the proportion of your source code that is covered by your unit tests. It can be very helpful while developing as it makes it easier to aim for as close to 100% as possible. It also highlights the code that is not covered by unit tests. For this project Istanbul will be configured to show a coverage summary in the console when a test or source code file changes, it will also generate a much more detailed HTML report that will be saved in the reports directory.
Stubs, Spies and Mocking – Sinon.js
For the tests, it is not good practice to have any network calls, so Sinon.js will be used to stub the data that would have been returned for each network call. Spies will also be used to test the functionality of methods.
Continuous Integration Testing – Travis CI
Since the code will be written following a very modular approach, and each module will be thoroughly tested standalone but it is of course vital that they work together seamlessly as they are meant to. A Travis CI configuration file will be written in a Yamel format, which will specify to Travis which tests need to be run in order to ensure the code is working as it should, and which versions of Node (and other technologies) the code will need to be run on. Then every time a new commit is made Travis will run tests to ensure everything continues to pass, and the code repository is not broken by the latest commit.
Dependency Checking – David
Since there are quite a few external dependencies that come together to make each component of the project possible, it is important to ensure that all the current dependencies are stable and have no bugs that could effect the running of TSV. For this automated dependency checking will be implemented with David-DM. When a dependency is no longer in date an notification will be triggered.
Automated Code Review’s – Code Climate
Code reviews can pick up on bad practices and inefficient code, such as including dependencies and not using them, variables in the wrong scope, poor identifiers, not following convention etc.. All of this information can help write better quality code. Code Climate also provides automated coverage testing in conjunction with Istanbul.
Headless Browser Testing – PhantomJS
For running functional frontend tests without having to use a browser, it can be automated in the same way as the other tests and can test the integration with other frontend libraries. PhantomJS also provides network monitoring utilities that can help cut down page load times.
Testing HTTP services – SuperTest
SuperTest is an agent driven library for testing node.js HTTP servers using a fluent API. It will be used for testing HTTP servers. It will be used to check the routing for the Express web service, to ensure with a given URL and parameters returns the expected output.