Fix Get-Help issue wih -Parameter option #8697

PowerShell · Jan 26, 2019 · 0e64b17 · 0e64b17
1 parent db1b309
commit 0e64b17
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Showing 2 changed files with 34 additions and 1 deletion.
diff --git a/src/System.Management.Automation/help/BaseCommandHelpInfo.cs b/src/System.Management.Automation/help/BaseCommandHelpInfo.cs
@@ -393,8 +393,21 @@ internal override PSObject[] GetParameter(string pattern)
                 return base.GetParameter(pattern);
             }
 
+            // The Maml format simplifies array fields containing only one object
+            // by transforming them into the objects themselves. To ensure the consistency
+            // of the help command result we change it back into an array.
+
+            var param = prmts.Properties["parameter"].Value;
+            PSObject paramPSObj = param as PSObject;
+            PSObject[] paramAsPSObjArray = new PSObject[1];
+
+            if (paramPSObj != null)
+            {
+                paramAsPSObjArray[0] = paramPSObj;
+            }
+
             PSObject[] prmtArray = (PSObject[])LanguagePrimitives.ConvertTo(
-                prmts.Properties["parameter"].Value,
+                paramAsPSObjArray != null ? paramAsPSObjArray : param,
                 typeof(PSObject[]),
                 CultureInfo.InvariantCulture);
 

diff --git a/test/powershell/engine/Help/HelpSystem.Tests.ps1 b/test/powershell/engine/Help/HelpSystem.Tests.ps1
@@ -503,6 +503,26 @@ Describe "Get-Help should accept arrays as the -Parameter parameter value" -Tags
     }
 }
 
+Describe "Get-Help for function parameter should be consistent" -Tags 'CI' {
+    BeforeAll {
+        $test = @'
+            function test {
+                param (
+                    $First
+                )
+            }
+'@
+        $testPath = Join-Path $TestDrive "test.ps1"
+        New-Item -ItemType File -Path $testPath -Force > $null
+        Set-Content -Path $testPath -Value $test
+    }
+
+    It "Get-Help for function parameter should be consistent" {
+        Import-Module $testPath
+        (Get-Help test -Parameter First).PSTypeName | Should -BeExactly "MamlCommandHelpInfo#parameter"
+    }
+}
+
 Describe "Help failure cases" -Tags Feature {
     It "An error is returned for a topic that doesn't exist: <command>" -TestCases @(
         @{ command = "help" },