Testing Private Functions with Pester

We’ve been busy beavering away on a new Powershell module that is comprised of many .ps1 files, that are loaded by a master/control .psm1 file when the module is imported. And, like all good Powershell citizens, we have many Pester unit tests for this code in accompanying .Tests.ps1 files.

As Powershell script modules permit us to control which functions should be exported with Export-ModuleMember and Pester allows us to test non-exported functions with the InModuleScope option, you might be wondering why we would ever need to be able to test private/internal functions?

Script Bundles

Whilst coding the new Powershell module, we have always had the desire to ensure that it could also be used as a ‘bundled’ .ps1 file. By bundle, we mean a single combined .ps1 file that can be included verbatim at the beginning of an existing script or by dot-sourcing it as required. Unfortunately – in this particular scenario – the internal module functions would be exposed and could potentially cause unnecessary confusion.

Here’s an example where both the ‘PublicFunction’ and ‘InnerPrivate’ functions would be exposed when bundled or dot-sourced into an existing .ps1 file.

If we only want the ‘PublicFunction’ visible then the simple solution to this is to nest the private function(s) inside the public function(s) like so:

Now only the ‘PublicFunction’ will be available. End of the story?

Internal Functions

Not quite; by hiding the functions we now cannot test them with Pester. I had a very brief conversation with Dave Wyatt on GitHub about this and it was agreed that this functionality should not be a part of the official Pester release.

To solve this particular issue, we have a simple function that will locate and return a function’s definition from within a .ps1 file as a script block. The function definition can then be dot-sourced into the current Pester scope to enable testing. Here’s an example Pester test file that will test our ‘InnerPrivate’ function:

If this code is of interest you can simply save the following code as a .ps1 file in Pester’s \Function directory, for example \Functions\FunctionDefinition.ps1, and Pester will automatically load it.


  1. As this code utilises the Abstract Syntax Tree (AST) it does require Powershell 3.0;
  2. If there are any dependencies on variables in the function’s parent scope these will need to be mocked/accounted for;
  3. Depending on how you install/update the Pester module, this might get overwritten when Pester is updated.

When we have more time we’ll put this up on Github so people can collaborate on changes. In the meantime, here’s a copy of the function.

App-V 5 Configuration Editor (ACE) v1.3 Released!

App-V 5 Configuration Editor (ACE) v1.3 Released!

Virtual Engine are pleased to announce the version 1.3 release of the App-V 5 Configuration Editor (ACE). This (free) utility provides a simple user interface for editing App-V 5 machine or user dynamic configuration files, without manually hacking the underlying XML files.

This release contains several reported bug fixes along with:

  • Many more Global Options added;
  • Enhancements to Terminate Child Processes;
  • Ability to open dynamic configuration files from the Command Line to allow integration into 3rd party products;
  • Source XML and Generated XML tabs now displayed with collapsible/expandable formatting.

App-V 5 Sequencer Template – Full VFS Write Mode

With the recent release of Hotfix 4 for App-V 5.0, Microsoft has now provided the ability to “Allow virtual applications full write permissions to the virtual file system”. This setting can be found in the sequencer under the “Advanced” tab as demonstrated in the screen shot below:

 Sequncer Full VFS

Should you wish to enable this setting as a default whenever you create a new package, then simply go ahead and add <FullVFSWriteMode>true<FullVFSWriteMode> into your sequencer template (.appvt), as you can see below. This setting is only valid where you have the App-V 5.0 SP2 Hotfix 4 sequencer installed.

And if you’re not currently using a template then I’d highly recommend you do. You’ll find a great article over at Rory Monaghan’s blog that explains the use of the sequencer template in more detail.


Creating .CAB files with Powershell

During our on-going development of online updateable Powershell help (more on that later) you quickly come to realise that each culture-specific set of help files is stored within its own 1980’s style cabinet (or .cab) file. When packing the .cab files for release, I like to automate (if you hadn’t already guessed!) as it makes things quick, easy and certainly less error prone.

Working with .cab files in Powershell requires use of MAKECAB.EXE which, fortunately, is distributed with each edition of Windows. In the good ol’ days we could use the MakeCab.MakeCab.1 COM object, but this has been deprecated since Windows Vista. I had a quick Google and couldn’t find anything easily reusable (except Ed Wilson’s post here) and thus this blog post.

I set to work, creating a Powershell advanced function that would easily allow me to package each culture-specific help file (or one or more files) into its own cabinet file. It would probably be more prudent to utilise .NET’s StringBuilder class but performance is not (currently) an issue or priority!

You never know I might come back and show you how we use this with Psake in the future… Here are some examples of how you can use it:

Here’s the full advanced function:


Searching for String Properties with Powershell

I had a requirement recently to parse a configuration file (let’s just say for documentation purposes) and I needed to retrieve a property/value pair which may or may not be present in a text line. Now, depending on the product we wish to document, we might have a line in the configuration file constructed as follows:

Now, if wanted the “-intfType” value we could split the string using the Powershell .Split() method like so:

However, there are two issues here:

  1. What happens if there are additional or missing properties (the index/order will change)?
  2. We were hoping/expecting to see “Xen Virtual” output and not just “Xen.

Here’s a quick function that will solve issue #1 (complete with case insensitivity):

Solving issue #2 is a little more involved as we need find the quoted text, escape it and then restore it when needed. The following Get-StringProperty advanced function will first replace all quoted spaces with “^” and then replace the quotes themselves with “^^”. This permits the split function to work as expected. Finally, everything is put back together just before we need it!

That’s much better Smile. Just for good luck I have also created a complimentary Test-StringProperty advanced function that tests whether a property name is present or not. This removes a lot of if ((Get-StringPropertyValue $SearchString “PropertyName”) -ne $null) { Do-Something } calls.

Some final words of warning:

  • If there are escaped (double) quotes then this function won’t work without some modification.
  • If the $SearchString just so happens to natively contain either “^” and/or “^^” it won’t (currently) work either.
  • If you have any improvements or feedback then please let me know.
  • Please test in your environment before putting any 3rd party or external code into production!

RES IT Store Web Portal Setup

We’ve had some confusion both internally and externally with some customers with the installation of the RES IT Store Web Portal. During the installation you will be prompted as to how you would like the IIS website to be configured:


This dialog is a little bit unclear as to what it is actually asking you. If you follow these simple guidelines, I’m sure you’ll be a whole lot clearer as to what is going on:

  • The RES IT Store Web Portal setup will create a new website – no ifs, buts or maybes.
    • It will not install to the default IIS website.
  • If you select the “Yes” option, the new website will be bound to port TCP port 80:
    • The existing default IIS website will also be bound to port 80 and therefore only one will start.
    • You will need to manually change the IIS default website port bindings.
  • If you select the “No” option, the new website can be bound to a specific TCP port:
    • Be careful as it will default to TCP port 80 but you can manually alter it.
    • The wizard will bind the Hostname specified to the new website as an IIS Host Header Name.

Our recommendation is to always select “No”, leave the default port binding and configure the host header value with your load-balanced fully qualified DNS alias, i.e. itstore.virtualengine.co.uk.


Windows 8.1 Update KB 2919355 Error 0×8007003

It’s been long, too long since the last post. However, never fear as we have plenty of new updates in the pipeline (pun intended!). This post is a little off topic but one that might help one or two people with the latest Windows 8.1 Update 1.

Whilst installing the latest Windows 8.1 Update 1 (and also KB2894853) on a couple of machines I saw the following error:

Installation Failure: Windows failed to install the following update with error 0×8007003: Update for Windows (KB2919355)

A quick Google landed me here which mentions that you will receive this error if the profiles directory is redirected with a registry key. As we have small SSDs in the office machines, the profile directory is indeed redirected to a bigger, spinning disk. This article is a little confusing (hence the post) as it states:

After putting a copy of UserProfiles on the C: drive, installation finished normally.

To fix the installation error we need to ensure that the Default directory is present in the redirected folder location, not on the C: drive. A quick copy of C:\Users\Default to D:\Users\Default fixed the installation issues with both updates.

App-V 5 Configuration Editor (ACE) v1.1 Released!

Virtual Engine are pleased to announce the version 1.1 release of the App-V 5 Configuration Editor (ACE). This (free) utility provides a simple user interface for editing App-V 5 the machine or user dynamic configuration files without manually hacking the underlying XML files. New in this release is the ability to Add, Delete and Edit shortcuts within the package, as well as various GUI improvements.

App-V 5 Configuration Editor User Guide

ACEWe’ve been working hard getting the App-V 5 Configuration Editor (ACE) ready for official release; take a look at the ACE page for a bit more information about why it was developed.

The purpose of this short blog to guide you through the ACE interface. There is an assumption here you have an understanding of the App-V 5 Dynamic Configuration files and how they are used, if not you might want to take a look at this Technet article.


Main Toolbar:

You will notice there are three main buttons in the tool bar as shown below:

Main Toolbar

image Opens an App-V XML file, i.e. a UserConfig.xml or DeploymentConfig.xml file. Once the file has been opened the contents will be parsed and displayed under the various tabs within the GUI.

image Saves the current App-V XML file, including any changes that have been made. You can give it a new name and Save As a different file, keeping your original one as is if necessary.

image Previews the changes that will be made to the App-V XML file before saving. This gives you the ability to check out the structure of the generated XML. It’s probably a good idea to point out here that you don’t need to preview the changes prior to performing a save.

Package Details:

This sections displays the Package Display Name, Package ID and Type of XML file opened, i.e. DeploymentConfig or UserConfig. Here is an example DeploymentConfig.xml opened below:

Package Details


Once an App-V 5 configuration XML file has been opened you can then begin to make changes as required using the tabs set out below.

User Configuration

Under the User Configuration tab you can change and view various options and configurations:

User Configuration


Various global options change be changed here if you so desire, e.g. altering the COM integration mode.


This tab allows you to View, Add, Edit or Delete any Shortcuts within the package.

If you want to delete an existing shortcut, simply select the row that contains the shortcut and press delete. Should you wish to add a new shortcut, I’d suggest you copy and paste an existing row and then edit the fields accordingly; we’ve added a context menu to make that task easy, should you not fancy using Ctrl+C and Ctrl+V  Smile.


Scripts (User Context)

This is really where ACE starts to make life simple Smile. You can easily define which scripts you’d like to add and to which script actions, e.g. PublishPackage, UnpublishPackage, StartVirtualEnvironment, TerminateVirtualEnvironment, StartProcess and ExitProcess. There is no need to worry about getting the syntax in the XML file right. There are some excellent blogs out there talking about using scripts in App-V 5.0, so I suggest you take a look here at one from Tim Mangan and Microsoft’s own Steve Thompson if you need some further background information.

NOTE: You might have noticed that not all the script actions are available under this tab, that’s simply because those excluded aren’t permitted to run under the User Configuration section of the XML file.

I think most of the options are self explanatory but, it’s good to point out that leaving the Timeout value at 0 means no timeout period will be set, i.e. it will wait indefinitely for it to finish so use with caution.

Scripts (User Context)

Machine Configuration

Under the Machine Configuration tab you can alter global options, configure scripts and control the termination of processes.

NOTE: this tab will only be available when you open a DeploymentConfig.xml file. This is because machine configuration items cannot be set in the UserConfig.xml file.

Machine Configuration


Here you’ll find any options that can be changed if you so desire.

Terminate Child Processes

You can define the path to an executable, that when closed, will terminate any child process running within the virtual environment.

Terminate Child Processes

Scripts (System Context)

Very much like the Scripts tab under User Configuration you can define which scripts you’d like to add to which machine script actions, e.g. AddPackage, RemovePackage, PublishPackage and UnpublishPackage.

NOTE: You might have noticed that not all the script actions are available under this tab, that’s simply because those excluded aren’t permitted to run under the Machine Configuration section of the XML file.

Scripts (System Context)


You can view both the source (original) XML and/or preview the generated XML under this tab.

Source XML

Source XML

This is simply where you can view your source App-V XML file as it was when you opened it.

Generated XML

Once you click the Preview button image this pane will display any changes that will be made to the App-V XML file, giving you the ability to check out the structure of the XML before saving if you wish. NOTE: You don’t have to preview the changes prior to performing a save.

The example below (highlighted in yellow) shows the changes made by ACE in the generated XML format. NOTE: ACE will not highlight the changes in the XML, we’ve done it here for clarity purposes only.

Generated XML

With any luck this brief guide has given you a good overview of how to use ACE and hopefully you’ll agree its pretty intuitive to use and should make editing the App-V 5 Dynamic Configuration files a lot, lot easier (well we think so anyway!)? :)