Formal analysis. We cannot test everything, and there is no need for it. This is particularly true in the case of behavioral testing. A lot of things that we cannot actually test at the present time (and hardly ever) will include all possible ways the features interact with each other. It is also impossible to test the behavior of a software program on each installation. The same applies to the interaction between your software package and someone else’s packages, the security check of your program, some communication protocols and many algorithms. Whenever for a number of reasons the complexity of testing grows faster than the complexity of the object being tested, a formal analysis, perhaps mathematical, is preferable to testing. We, however, need to perform testing to make sure that our analysis itself is free of errors.
Design. A good project has few errors and is easily tested. It is much easier to design something that cannot be tested than anything that can be tested. It is much easier to design something that is completely impossible to maintain than to design something that may be maintained. The most competent requirements are brought to nothing by ill-conceived projects that cannot be verified with a finite number of tests.
Formal inspection is the primary method of preventing errors, and this fact has been repeatedly confirmed. Software development process that does not include formal inspection is obviously defective, and the elimination of errors in it is much more dependent on testing.
You are welcome to outsource qa to qualified Ukrainian specialists who provide their services to people all over the world. Get your testing work done cost-effectively and competently.
Self-testing. Testing done by the programmers themselves is much more effective than testing performed by someone else. The same applies to testing carried out by the software development team. Similarly, testing inside the organization that developed the software is more effective than external testing (i.e., beta testing) of the same software. This does not reject the idea that independent testing can be extremely effective, since efficiency is not the only criterion for determining who will conduct testing and what type of testing will be conducted.
If an independent tester repeats a test previously performed by a developer, or simply performs testing that should be performed during the development, in this case independent testing does not bring any information at all, in fact, it does not make sense.