Год назад, 20 июля 2019 года, исполнилось 50 лет с момента первой в истории высадки на Луну. Нил Армстронг и Эдвин Олдрин оставались на Луне 21,5 часов, и на 2,5 часа выходили на поверхность. Программа «Аполлон» и высадка на Луну часто упоминаются как одно из величайших достижений в истории человечества. Мне интересно было посмотреть на это событие с точки зрения разработки и тестирования ПО. Я нашёл книги и документы на сайте NASA, в которых описаны детали создания ПО для этой миссии. Самые интересные для меня цитаты я собрал в отдельной заметке.

Например про ценность юнит-тестирования:

"On June 13, Tindall reported that the AS-204 program undergoing integrated tests had bugs in every module. Some had not been unit tested prior to being integrated. This was a serious breach of software engineering practice. If individual modules are unit tested and proven bug-free, then bugs found in integrated tests are most likely located in the interfaces or calling modules. If unit testing has not been done then bugs could be anywhere in the program load, and it is very difficult to identify the location properly. This vastly increases the time and, thus, the cost of debugging. It causes a much greater slip in schedule than time spent on unit tests. Even worse, Tindall said that the test results would not be formally documented to NASA but that they would be on file if needed."

Про синдром неприятия чужой разработки в проекте:

"The impression one gains from documents and interviews is that both Rockwell and IBM fell victim to the “not invented here” syndrome: If we didn’t do it, it wasn’t done right. For example, Rockwell delivered the ascent requirements, and IBM coded them to the letter, thereby exceeding the available memory by two and a third times and demonstrating that the requirements for ascent were excessive. Rockwell, in return, argued for 2 years about the nature of the operating system, calling for a strict time-sliced system, which allocates predefined periods of time for the execution of each task and then suspends tasks unfinished in that time period and moves on to the next one. The system thus cycles through all scheduled tasks in a fixed period of time, working on each in turn. Rockwell’s original proposal was for a 40-millisecond cycle with synchronization points at the end of each102. IBM, at NASA’s urging, countered with a priority-interrupt-driven system similar to the one on Apollo Rockwell, experienced with time-slice systems, fought this from 1973 to 1975, convinced it would never work."