How to know if error from dotnet build command with powershell

Question

I want custom script when my dotnet build command failed. How to get errors list or not success flag when the 'dotnet build' failed with errors compilation for example, or when 'dotnet test' failed, with powershell.

I want equivalent code

dotnet test
if (!$result.Successful) {
    $errorMessage = ""
    if ($result.Error -ne $null) {
        $errorMessage = $result.Error.Message
    }
    Write-Host "##vso[task.logissue type=error;] error"
    Write-Host "##vso[task.complete result=Failed;]"
    Exit -1
}

Answer 1

You can merge the standard output and error streams with the > stream redirection operator, and then inspect the $LASTEXITCODE automatic variable to see if the call succeeded or not:

# Merge all streams into stdout
$result = dotnet test *>&1

# Evaluate success/failure
if($LASTEXITCODE -eq 0)
{
    # Success
}
else
{
    # Failed, you can reconstruct stderr strings with:
    $ErrorString = $result -join [System.Environment]::NewLine
}