Store output of command with error - powershell

Question

I want to store the output of this command
git checkout master
the output of this command has two states.
success - the command outputs:
Switched to branch 'X'
failure - the command outputs
Your local changes to the following files would be overwritten by checkout <list files> : Please commit your changes or stash them before you switch branches. Aborting
I want to store the output and check if it succeeds by checking for the string abort.
This is what I've tried.
$output = git checkout master 2>&1
if ($output.Contains("Aborting")) {
Write-Host $output -BackgroundColor Red
} else {
Write-Host $output
}
but $output produces something like this, when in the second state:
It seems like the command completed, but it was the wrong syntax. How do I fix this? I would like to to ouput

Answer 1

Make sure that your command's stderr output is converted to regular strings:
$output = [string[]] (git checkout master 2>&1)
Without the [string[]] cast, stderr output lines are stored in $output as [System.Management.Automation.ErrorRecord] instances, and outputting such instances later somewhat misleadingly prints them as if they were PowerShell errors.
(Note that PowerShell Core no longer exhibits this behavior: while stderr lines are still captured as [System.Management.Automation.ErrorRecord] instances, they now print as regular strings.)