Report the real exception type from Should-Throw

src/functions/assert/Exception/Should-Throw.ps1

@@ -143,17 +143,45 @@
 function Get-ErrorObject ($ErrorRecord) {
 
     if ($ErrorRecord.Exception -like '*"InvokeWithContext"*') {
-        $e = $ErrorRecord.Exception.InnerException.ErrorRecord
+        # The scriptblock ran via InvokeWithContext, so a terminating error is wrapped in
+        # a MethodInvocationException. Unwrap it so we report the same exception that
+        # & { } would have surfaced in $_ (#2873).
+        $inner = $ErrorRecord.Exception.InnerException
+        $record = $inner.ErrorRecord
+
+        # When the inner exception carries an error record whose own exception is just a
+        # ParentContainsErrorRecordException placeholder (e.g. a parameter binding failure,
+        # or a division by zero), the real exception is the inner exception itself.
+        # Otherwise the record's exception is the one the caller threw - for example
+        # Write-Error -ErrorAction Stop wraps the original record in an
+        # ActionPreferenceStopException, and Get-Item -ErrorAction Stop does the same.
+        if ($null -eq $record) {
+            $realException = $inner
+            $record = $ErrorRecord
+        }
+        elseif ($record.Exception -is [System.Management.Automation.ParentContainsErrorRecordException]) {
+            $realException = $inner
+        }
+        else {
+            $realException = $record.Exception
+        }
+
+        [PSCustomObject] @{
+            ErrorRecord           = $record
+            ExceptionMessage      = $realException.Message
+            Exception             = $realException
+            ExceptionType         = $realException.GetType()
+            FullyQualifiedErrorId = $record.FullyQualifiedErrorId
+        }
     }
     else {
-        $e = $ErrorRecord
-    }
-    [PSCustomObject] @{
-        ErrorRecord           = $e
-        ExceptionMessage      = $e.Exception.Message
-        Exception             = $e.Exception
-        ExceptionType         = $e.Exception.GetType()
-        FullyQualifiedErrorId = $e.FullyQualifiedErrorId
+        [PSCustomObject] @{
+            ErrorRecord           = $ErrorRecord
+            ExceptionMessage      = $ErrorRecord.Exception.Message
+            Exception             = $ErrorRecord.Exception
+            ExceptionType         = $ErrorRecord.Exception.GetType()
+            FullyQualifiedErrorId = $ErrorRecord.FullyQualifiedErrorId
+        }
     }
 }
 

tst/functions/assert/Exception/Should-Throw.Tests.ps1

@@ -40,6 +40,12 @@ Describe "Should-Throw" {
         It "Fails when exception is thrown, but is not the expected type nor iheriting form the expected type" {
             { { throw [InvalidOperationException]"This operation is invalid!" } | Should-Throw -ExceptionType ([ArgumentException]) } | Verify-AssertionFailed
         }
+
+        It "Matches the real exception type for a parameter binding failure (#2873)" {
+            # Used to report ParentContainsErrorRecordException instead of the real type.
+            { Get-Item "/non-existing" -NonExistentParameter 1 } |
+                Should-Throw -ExceptionType ([System.Management.Automation.ParameterBindingException])
+        }
     }
 
     Context "Filtering with exception message" {
@@ -242,5 +248,39 @@ InPesterModuleScope {
             $err.ExceptionType | Verify-Equal ([Management.Automation.ItemNotFoundException])
             $err.FullyQualifiedErrorId | Verify-Equal 'PathNotFound,Microsoft.PowerShell.Commands.GetItemCommand'
         }
+
+        # #2873 - the exception type must match what & { } would surface in $_, not the
+        # ParentContainsErrorRecordException placeholder that some inner error records carry.
+        BeforeAll {
+            function Get-ThrownError ([scriptblock] $ScriptBlock) {
+                try {
+                    $eap = [PSVariable]::new("erroractionpreference", 'Stop')
+                    $null = $ScriptBlock.InvokeWithContext($null, $eap, $null) 2>&1
+                }
+                catch {
+                    return Get-ErrorObject $_
+                }
+            }
+        }
+
+        It 'Reports the real exception type for a parameter binding failure (#2873)' {
+            $err = Get-ThrownError { Get-Item "/non-existing" -NonExistentParameter 1 }
+            $err.ExceptionType | Verify-Equal ([System.Management.Automation.ParameterBindingException])
+        }
+
+        It 'Reports the real exception type for a division by zero (#2873)' {
+            $err = Get-ThrownError { 1 / $null }
+            $err.ExceptionType | Verify-Equal ([System.Management.Automation.RuntimeException])
+        }
+
+        It 'Reports the wrapped exception for Write-Error -ErrorAction Stop (#2873)' {
+            $err = Get-ThrownError { Write-Error -ErrorAction Stop -Exception ([System.ArgumentException]"boom") }
+            $err.ExceptionType | Verify-Equal ([System.ArgumentException])
+        }
+
+        It 'Reports the wrapped exception for a cmdlet with -ErrorAction Stop (#2873)' {
+            $err = Get-ThrownError { Get-Item "/non-existing" -ErrorAction Stop }
+            $err.ExceptionType | Verify-Equal ([System.Management.Automation.ItemNotFoundException])
+        }
     }
 }