test-assertion.ps1

PowerShell script Reference

A .ps1 file contains a PowerShell script. PowerShell reads the file and runs the commands in order. Scripts automate administration tasks on Windows, Linux, and macOS. The language operates on objects, not only on text. The execution policy of the system controls if a script can start.

A file extension is only a part of the file name. It does not give a guarantee about the format or the content of a file. But on Windows, the extension selects the program that opens the file.