Language testing is central to language teaching. It provides goals for language teaching, and it monitors, for both teachers and students, success in reaching those goals. Its influence is very strong. It provides a methodology for experiment and investigation in both language teaching and language learning/acquisition. The three basic requirements of a good language text are validity, reliability and practicality. The test which measures what we want to measure and measures it in a manner which we find acceptable is a valid test. If it does this without significant variation when the examiners and other test conditions are changed, it is a reliable test. And, if it can do this with ease and economy, it is a practical test.

The two most important aspects of validity are content and construct validity. If a test has content validity it means that the test questions cover a fair sample of the language structures and skills that the test claims to be measuring. In order to be able to see whether a test does have content validity, the test writers ought to specify clearly what areas of language their test claims to cover. A test has construct validity if it can show that it measures only what it claims to measure and nothing else. In order for a test to maximize its construct validity it should test whatever it claims to test as directly as possible. A test is said to be reliable if it gives the same results when it is given on different occasions or when it is used by different people. There are two aspects to reliability: test reliability and scorer reliability. Test reliability refers to how consistent scores are on a test. A test has scorer reliability if there is a high level of agreement between different people marking the same test paper. Scorer reliability is also important for a test. One way to achieve this has been to write items that require no judgment at all from individual scorers. Besides, there is no point in teachers starting to try to design valid and reliable language tests without first considering the practical realities of their own specific L2 learning context.