This lesson describes in more details about why complete testing is impossible. I attached also pdf document about the same topic mentioned in the lesson.
In this video you will learn about:
Software testing foundations, addressing the impossibility of achieving complete testing due to the vast number of variables, combinations, and user interactions. Emphasizing the limitations of exhaustive testing, the example of testing a function reading a 32-bit word illustrates the challenges. Doug Hoffman's case study on testing the MassPar computer reveals that even billions of tests may not be exhaustive, and overlooking certain inputs, unexpected user behaviors, or easter eggs can lead to critical issues. The lecture stresses the need for strategic, representative testing and acknowledges the impracticality of testing every possible scenario.
Discussed terminology:
distinct tests
what would it mean to test everything
human inputs
timeouts
input variables
extreme inputs
Read more about the impossibility of complete testing here.