Writing, notes, and things I'm thinking about.
A complete beginner-to-confident series on testing PowerShell with Pester 5 — written offline, finished first, and released as one full set.
You have all the pieces. Now turn them into a habit: the red-green-refactor TDD loop in PowerShell, a checklist drawn from all six sections, the beginner pitfalls to dodge, and where to go next.
Tests that only run when you remember them protect nothing. Wire the Pester 5 configuration object into GitHub Actions and Azure Pipelines so your suite runs on every push, publishes results, and fails the build on red.
Passing flags to Invoke-Pester works until you have ten of them. Learn the Pester 5 configuration object: Run.Path, Output.Verbosity, Filter.Tag, CodeCoverage, and TestResult, all in one tidy, reusable, version-controllable object.
Code coverage tells you which lines your tests actually exercised. Learn to enable it with New-PesterConfiguration, read the missed-lines report, emit JaCoCo XML, and treat coverage as a guide rather than a goal.
Notes from a PowerShell-first DBA managing a farm of SQL Server instances.
SqlSpnManager was the first module I published to PowerShell Gallery — and not the first one I built. Here's what it does, why it exists, and how the plan-before-execute design saves you from yourself.
A deep look at how GitEasy's core command works under the hood — including the credential security problems I found and fixed along the way.
Mocking is the feature beginners get most wrong. Learn why a Mock 'doesn't take' inside a module, fix it with InModuleScope, test private functions, and recognize over-mocking as a design smell.
A blanket mock is blunt. Learn Pester 5's -ParameterFilter so one command behaves differently depending on its arguments, and verify the exact call you care about with Should -Invoke.
Sometimes the behavior is the call itself. Use Pester 5's Should -Invoke to prove a command ran exactly once, or never ran at all, with the right -Times, -Exactly, and -Scope.
SSMS is a great editor. It's a terrible loop. At thirty instances, the case for PowerShell stops being a preference and starts being math.
Learn the core Mock mechanic in Pester 5: swap a real command for one you control, return canned values, simulate failures, and where the Mock must live so it actually takes effect.
Mocking lets you test your logic without triggering real-world consequences like sending email or deleting files. Learn the concept, the good candidates, and when to leave a command alone.
When your suite takes minutes, run only the fast ones becomes a daily need. Learn to tag tests in Pester 5 and filter them with the configuration object using Filter.Tag and Filter.ExcludeTag.
Copy-pasting an It block five times with different numbers is a smell. Learn to write one parametrized test that runs over a table of cases using Pester 5's -ForEach and -TestCases.
Code that writes files should not write them to your real disk during a test. Pester gives you a per-test sandbox with TestDrive and TestRegistry that cleans itself up automatically.
Toy tests use inline functions, but real testing means loading your own code. Learn the two clean ways to get a function under test in Pester 5: dot-sourcing a script and importing a module.
Organize a PowerShell project so Pester finds every test by convention: the .Tests.ps1 rule, one file per source file, Unit vs Integration folders, and robust paths with PSScriptRoot.
A test you can read in five seconds is a test you'll trust at 2 a.m. Learn the Arrange-Act-Assert pattern and the should...when naming style that make Pester tests self-documenting.
Pester 5 runs your test file in two phases — Discovery and Run. Understand that model and the four setup/teardown blocks fall into place.
Three Pester keywords, one job each. Learn how Describe, Context, and It nest to make a growing test suite read like a specification.
Use Pester's -Not switch correctly—where it goes, why negative assertions like 'not null' are weak claims, and how to prefer strong positive assertions instead.
Test the error paths in your PowerShell code with Should -Throw—wrap the act in a scriptblock, assert on the message and ErrorId, and use Should -Not -Throw for must-succeed cases.
Go beyond equality with Pester's numeric, string, and collection operators—-BeGreaterThan, -Match, -Like, -Contain, -BeIn, and -HaveCount—and assert on object properties.
Meet Pester's Should command and the five everyday operators—-Be, -BeExactly, -BeNullOrEmpty, -BeTrue/-BeFalse, and -BeOfType—that cover most real assertions.
Run Pester tests on a file or a whole folder, read the pass/fail summary, decode an Expected-vs-But-was failure, turn up the detail, and understand the exit code that CI lives by.
Write the smallest useful Pester test using Describe, It, and Should, then test a tiny real function and watch it go from red to green.
Get to a clean Pester 5.x install: check your current version, understand why Windows ships the old 3.4, install from the PSGallery correctly, and verify it loaded.
A gentle, vendor-neutral introduction to automated testing for PowerShell scripters: what Pester is, unit vs integration in plain English, and what tests actually buy you.