AbsPath Return the absolute path of the directory or panic if error.

GetTempFile Get a temporary file for writing and reading.

GetTestBinCmd return a command to run the test binary in a sub-process, passing it flags as fixtures to produce expected output; `TestMain`, will be run automatically.

ResetDir Reset a directory by emptying it out.

RunMain Used for running the application's main function from a call to a test function, but in a sub process.

TempFileSwap Swap a file pointer for a temporary file pointer.

VerboseSubCmdOut Serves as a pass-through function display output to stdout and stderr respectively, but only if the verbosity flag is turned on.