Invoke pester8/18/2023 There might be one mock for reading from the database, and another mock for writing out the file results, for example. Obviously, this is a very simplified example a real test would test many things beyond just the file existence, and likely include other mocks. The unit test now tests for both possibilities. You can now see the two tests pass, the first testing for the file already existing, the second for when the file didn’t exist. Running the Invoke-MockTests.ps1 now returns following results. ![]() In the downloads you’ll find a script Invoke-MocksTests.ps1. You are only testing the code within the PretendToDoSomething function. If you are running this in an automated fashion, for example as part of your source code management, then the verbose switch should be removed.īy using a mock, you can easily test that the code correctly handles the condition of a file existing without actually needing to create a file, nor exposing any bugs that may be lurking in the Test-Path cmdlet. When running tests manually this can be a useful tool for uncovering any errors. You’ll also note the use of the -Verbose switch to display additional information. With the test done by the It function, it ensures the function correctly returns false if the file is already present. Within the PretendToDoSomething function, if Test-Path finds the file, it provides a warning and returns a value of false. The PretendToDoSomething function is called and the result is placed in the $aTestResult variable. At the top of the test, you’ll find this code: If you want to follow along you can always download the complete file from the GitHub site as 1. Ultimately, you’ll need to decide which cmdlets are foundational and can safely skip testing / mocking, and which ones may, through potential bugs or being vulnerable to external conditions such as missing internet, drives, etc., need to be tested and / or mocked in your code. By mocking it, you remove the need to spend time debugging for those types of environmental conditions. As stated earlier, when using Test-Path, there are numerous things that may go wrong such as missing drives or folders. Many of the Write-* cmdlets would fall into this category. And while they might be correct, at some point you must use cmdlets so foundational, that you just need to accept them. NOTE: Some might also argue cmdlets such as Write-Verbose or Write-Host would also violate isolation rules. ![]() Just update this to point to the folder you want to place the demos in. To make it easy at or near the beginning of each script is a variable, $dir, which points to the demo folder. However, you are not locked into this structure. Locally, I continue to use the same C:\PowerShell\Pester-Demo folder as the previous article. The demos are in the same location on the author’s GitHub repository as the previous article. ![]() ![]() Next, I’ll cover the way to distinguish the different types of test within Pester, and how to code your tests appropriately. I’ll also introduce a new concept, TestPath. I had mentioned the concept of mocks in the previous article, in this one you’ll see what a mock is and how to use it. In this article, we’ll continue our journey with Pester. We rolled up our sleeves next, learning how to install Pester, invoke a Pester test, and how to construct a test using the Describe, Context, and It functions. In addition, the importance of having good requirements was stressed. The types of testing, unit, integration, and acceptance were discussed. In part 1 of this series, Introduction to Testing Your PowerShell Code with Pester, I covered the basics of using the Pester module to test your PowerShell code.
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