Trick MSI API into thinking that an upgradecode is installed

Question

I'm testing the compatibility of two products (A) and (B) within a TestAutomation project. The test verifies that product (B), which is actually the product under test, can be installed eventhough (A) is already installed --> to do so, the installer of (B) looks up if the UpgradeCode of (A) is present.

NOTE: I already know the UpgradeCode of (A). What I'm trying to do is to write it into the table that will be looked-up upon installing (B), WITHOUT actually installing the MSI of (A) - this is kind of like a "mock" in integration-testing.

The test is running on a VM where (A) is not already installed by default. My goal would be to write a script which would allow me to skip the "real" installation of (A).

QUESTIONS:

1. I'm not sure of where it looks the UpgradeCode up. It is NOT looking it up in the registries (I aready tried that hack). I have found the UpgradeCode within the Win32_Property table... is that the right place to look into?

2. My guess is that I have to emulate the API-call, with which the original MSI from (A) sets its UpgradeCode... any idea of how that works? Possibly with a Powershell script. I have seen online people modifying the WMI properties tables can with calls to gwmi (then using put) or swmi, but all my attempts so far failed.

NOTES:

• I do not really know my way around with the Windows Installer nor with PowerShell... this is not at all what I usually do. An answer in Layman terms would be much appreciated.
• I know that there are other ways around this (e.g. a dedicated VM or performing a "real" installation of (A)), but I'd like to know how to achieve this programmatically.
• Why I need to do that? It's an automated test that only concerns the installer of (B). I do not want the success of my test to be depending from (A)'s successfull download or installation.

Answer 1

The easiest way to do a test without installing the actual A would be to produce a small MSI with the same UpgradeCode and ProductCode and install it. I can't see why you want to "fake" it when you can just do the real thing.

If you want to prevent the install of B when A is already installed you could add A's UpgradeCode to B with OnlyDetect=yes, that will set a property that can be used to prevent B from being installed. It's not clear what the context is for not installing B, whether you have external launchers, a bootstrapper, or which tool is being used to generate the MSI (because some tools will give you help if you want to skip B if A is installed with their built-in detection features).

Answer 2

You can get the UpgradeCode via WMI (Win32_Property WMI table) or via MSI API (Windows Installer Database - registry).

I would not hack the upgrade code in the Windows Installer Database for any reason. Why do you need to fake the UpgradeCode? Is the install of product A very large?

1. WMI / PowerShell / VBScript:

   • How can I find the Upgrade Code for an installed MSI file?
   • WMI is very slow to use, and can cause side effects such as self-repairs and in certain cases spam the event log with error messages. See the Disclaimer section here.

2. MSI API:

   • You can use MSI API COM calls (VBScript, Javascript, etc...) or MSI API Win32 calls (C++).
   • Here is a hacky way of getting the Upgradecode via a session object using VBScript. I am not sure what side-effects - if any - result from spinning up many session objects: Is MsiOpenProduct the correct way to read properties from an installed product?