This is an experimental project to show a bug in the build_test package.
The testBuilder method of the package does not work properly when the generator is extended from GeneratForAnnotated class. The test gives Builder failed to write asset error and the code is not generated. However after changing the generator to be extended from Generator class, the method works properly.
As said in #1828 and #2292 of the build package, it can work in some machines with the same code base which makes it hard to reproduce the problem. You can find the proof of the problem on the links below.
The video: https://1drv.ms/u/s!ArT19eL-omOjhY0wxeUJsLVZeTwf4Q
#1828: dart-lang/build#1828 #2292: dart-lang/build#2292
One of the main developers of the package says in his comment, there is no bug and it works when the project is set up correctly. I suggest, either to improve the code in order to achieve easier test setup or to improve the documentation in order to prevent any confusion while working with the package, as it is quite hard to detect a problem especially when almost identical codes give different results.
The comment: dart-lang/build#2292 (comment)
If you think there is something wrong in this repository which causes the problem mentioned here, please feel free to send a pull request with the corrected code, or open an issue stating the source of the problem.