internal static Collection <PSObject> InvokeAndAssertForErrors(this System.Management.Automation.PowerShell powershell, string expectedErrorMsg = null) { powershell.Streams.ClearStreams(); var result = powershell.Invoke(); if (string.IsNullOrEmpty(expectedErrorMsg)) { Assert.IsFalse(powershell.HadErrors, powershell.GetPowershellErrorMessage()); } else { Assert.IsTrue(powershell.HadErrors); } Assert.AreEqual(expectedErrorMsg, powershell.GetPowershellErrorMessage()); return(result); }