The cmdtest package simplifies testing of command-line interfaces. It provides a simple, cross-platform, shell-like language to express command execution. It can compare actual output with the expected output, and can also update a file with new "golden" output that is deemed correct. Start using cmdtest by writing a test file with commands and expected output, giving it the extension ".ct". All test files in the same directory make up a test suite. See the TestSuite documentation for the syntax of test files. To test, first read the suite: Then configure the resulting TestSuite by adding commands or enabling debugging features. Lastly, call TestSuite.Run with false to compare or true to update. Typically, this boolean will be the value of a flag: