Fix reason validation on adapter

adapters/powershell/Tests/TestAdapter/testadapter.resource.ps1

@@ -64,6 +64,15 @@ switch ($Operation) {
         )} | ConvertTo-Json -Depth 10 -Compress
     }
     'Validate' {
-        @{ valid = $true } | ConvertTo-Json
+        # Test validation with reason field
+        if ($inputobj.resources[0].properties.TestCaseId -eq 99) {
+            @{ 
+                valid = $false
+                reason = "TestCaseId 99 is not allowed for testing purposes"
+            } | ConvertTo-Json
+        }
+        else {
+            @{ valid = $true } | ConvertTo-Json
+        }
     }
 }

adapters/powershell/Tests/powershellgroup.resource.tests.ps1

@@ -315,6 +315,23 @@ Describe 'PowerShell adapter resource tests' {
         }
     }
 
+    It 'Verify validate operation shows reason on adapted resource' {
+        $oldPath = $env:PATH
+        try {
+            $adapterPath = Join-Path $PSScriptRoot 'TestAdapter'
+            $env:PATH += [System.IO.Path]::PathSeparator + $adapterPath
+
+            # Test with invalid TestCaseId that should trigger validation failure with reason
+            $r = '{"TestCaseId": 99}' | dsc resource get -r 'Test/TestCase' -f - 2>&1
+            $LASTEXITCODE | Should -Not -Be 0
+            $errorOutput = $r | Out-String
+            $errorOutput | Should -Match "TestCaseId 99 is not allowed for testing purposes"
+        }
+        finally {
+            $env:PATH = $oldPath
+        }
+    }
+
     It 'Dsc can process large resource output' -Pending {
         try {
             $env:TestClassResourceResultCount = 5000 # with sync resource invocations this was not possible

lib/dsc-lib/src/dscresources/command_resource.rs

@@ -866,7 +866,8 @@ fn verify_json(resource: &ResourceManifest, cwd: &Path, json: &str) -> Result<()
             return Ok(());
         }
 
-        return Err(DscError::Validation(t!("dscresources.commandResource.resourceInvalidJson").to_string()));
+        let reason = result.reason.unwrap_or_else(|| t!("dscresources.commandResource.resourceInvalidJson").to_string());
+        return Err(DscError::Validation(reason));
     }
 
     // otherwise, use schema validation