Description Of Changes

This commit adds the ability to output the previous package version, during say a choco upgrade command, as an environment variable. Prior to this commit, it was only the package version that was currently being installed/upgraded that was presented as an environment variable.

The method that is responsible for writing the environment variables is the PreparePowerShellEnvironment method, which is defined by the IPowershellService interface. Rather than make a change to the interface to pass in this information, it was decided to add a property to the ChocolateyConfiguration class, which is currently being passed through to this method. This means that there is some maintainability in place, where additional information can be passed through as environment variables in the future, should the need arise. This would be done by simply adding another item into the Dictionary.

Pester tests have been updated to allow the testing for this new environment variable during the process of upgrading a package version.

Motivation and Context

This is needed since there are times that during an upgrade you want to do something based on which version is being upgraded from. For example, you might have to do "something" when upgrading from version 1.0.0 and "something else" when upgrading from version 2.0.0. Being able to inspect the previous package version as an environment variable, in the same way as you can the package version being currently installed is very useful, and also consistent with how package maintainers get other information.

Testing

1. Clone this repository, and check out PR branch
2. Open project in Visual Studio, and set a breakpoint on line 1719 of the NugetService.cs class
3. Run install vscode --version 1.100.2 -n
4. The above breakpoint should not be hit, as the install is a different code path
5. Run upgrade vscode -n
6. The above breakpoint should be hit for first the vscode.install package, with the previous version of 1.100.2 and the current version 1.100.3
7. Continue code execution
8. The above breakpoint should be hit for first the vscode package, with the previous version of 1.100.2 and the current version 1.100.3
9. Each time, the config.Information.EnvironmentVariables should either have a Count of 0, or have a null value for the ChocolateyPreviousPackageVersion entry.

Operating Systems Testing

• Windows 11

Change Types Made

• Bug fix (non-breaking change).
• Feature / Enhancement (non-breaking change).
• Breaking change (fix or feature that could cause existing functionality to change).
• Documentation changes.
• PowerShell code changes.

Change Checklist

• Requires a change to the documentation.
• Documentation has been updated.
• Tests to cover my changes, have been added.
• All new and existing tests passed?
• PowerShell code changes: PowerShell v3 compatibility checked?

Related Issue

Fixes #1713