Theses cache files are generated by atest. To regenerate them:

78ea54ef315f5613f7c11dd1a87f10c7.cache -> m atest && atest-dev -c --host hello_world_test

cd66f9f5ad63b42d0d77a9334de6bb73.cache -> Open test_finders/test_info.py, and in the constructor of TestInfo, add self.some_new_property = "foo". Then run m atest && atest-dev -c --host hello_world_test. The result will be under the 78ea... name, but just rename it to the cd66... name.

The new files will be in ~/.atest/info_cache/