Pester is a PowerShell testing framework and behavior-driven development tool used to write and run automated tests for scripts and modules. It defines and verifies software behavior through human-readable specifications to validate that code behaves as expected.
The project includes a native mocking library that replaces real functions and commands with controlled implementations, allowing for the isolation of code and verification of command invocations without altering the system environment. It also functions as a code coverage tool that measures the percentage of executed lines during test runs to identify untested logic and branches.
Broad capabilities cover the management of test lifecycles through shared setup and teardown logic and the organization of test suites into nested groups. The framework provides specialized assertions to validate code behavior and integrates with continuous integration servers to automate test execution within build pipelines.
