Mastering Windows PowerShell Scripting - Third Edition

Creating a custom rule

A script analyzer rule is a function within a module. A script analyzer allows rules to be written to evaluate AST nodes or tokens.

The name of the function is arbitrary. The community examples use the verb measure; however, use of this verb is not mandatory and does not affect discovery. The script analyzer engine examines each function in the custom rule module, looking for parameters following a particular style. If the such a parameter is found, the function is deemed to be a rule.

If a rule is expected to act based on an AST node, the first parameter name must end with ast. The parameter must use an AST type, such as System.Management.Automation.Language.ScriptBlockAst.

If a rule is expected to act based on a token, ...