Unit tests enjoin a developer that the code is doing things right; functional tests enjoin a developer that the code is doing the right things.
Unit tests:
Unit tests are written from a programmer's perspective. They ensure that a detail method of a aeroplane successfully performs a laid upwards of specific tasks. Each exam confirms that a method produces the expected output when given a known input.
Writing a suite of maintainable, automated unit of measurement tests without a testing framework is virtually impossible. Before yous begin, direct a framework that your squad agrees upon. You volition last using it constantly, in addition to thence yous amend similar it. There are several unit-testing frameworks available from the Extreme Programming Web site. The i I am nearly familiar amongst is JUnit for testing Java code.
Functional tests:
Functional tests are written from a user's perspective. These tests confirm that the organization does what users are expecting it to.
Many times the evolution of a organization is likened to the edifice of a house. While this analogy isn't quite correct, nosotros tin dismiss extend it for the purposes of agreement the divergence betwixt unit of measurement in addition to functional tests. Unit testing is analogous to a edifice inspector visiting a house's structure site. He is focused on the diverse internal systems of the house, the foundation, framing, electrical, plumbing, in addition to and thence on. He ensures (tests) that the parts of the theater volition piece of occupation correctly in addition to safely, that is, regard the edifice code. Functional tests inwards this scenario are analogous to the homeowner visiting this same structure site. He assumes that the internal systems volition bear appropriately, that the edifice inspector is performing his task. The homeowner is focused on what it volition last similar to alive inwards this house. He is concerned amongst how the theater looks, are the diverse rooms a comfortable size, does the theater check the family's needs, are the windows inwards a skilful location to direct deal of the forenoon sun. The homeowner is performing functional tests on the house. He has the user's perspective. The edifice inspector is performing unit of measurement tests on the house. He has the builder's perspective.
Like unit of measurement tests, writing a suite of maintainable, automated functional tests without a testing framework is virtually impossible. JUnit is really skilful at unit of measurement testing; however, it unravels when attempting to write functional tests. There is no equivalent of JUnit for functional testing. There are products available for this purpose, but I bring never seen these products used inwards a production environment. If yous can't notice a testing framework that meets your needs, you'll bring to build one.
No affair how clever nosotros are at edifice the projects nosotros piece of occupation on, no affair how flexible the systems are that nosotros build, if what nosotros attain isn't usable, we've wasted our time. As a result, functional testing is the nearly of import constituent of development.
Because both types of tests are necessary, you'll demand guidelines for writing them.