collection of frequentely used test functionalities

 The primary objective of Test::Expander is to provide additional convenience
 functions for tests based on Test2::V0, considering boilerplate aspects that
 seem to be important in a notable number of cases. These are among other
 things:
 .
 Repeated application of class/module and/or method/function to be tested.
 .
 The frequent necessity of introduction of a temporary directory and/or file.
 .
 Another fuctionality frequently used in tests relates to the work with files
 and directories: reading, writing, creation, etc.
 .
 Run tests in a clean environment, where only explicitly mentioned environment
 variables are set and environment variables from the "outside world" cannot
 affect the execution of tests.