Writes very small test files to disk that can be used to test the package.
The entire package works by reading zip-compressed data files provided by the
various hire bicycle systems. This function generates some equivalent data
that can be read into an
SQLite database by the
store_bikedata() function, so that all other package functionality can
then be tested from the resultant database. This function is also used in the
examples of all other functions.
bike_write_test_data(data_dir = tempdir())