Fix tests

Author: Gijsreyn

src/dsc/psresourceget.ps1

@@ -161,16 +161,18 @@ class PSResourceList {
     }
 
     [string] ToJson() {
-        $resourceObjects = if ($this.resources) {
-            @($this.resources | ForEach-Object {
+        ## Assign the array directly so that an empty list serializes as [] rather than null
+        [object[]]$resourceObjects = @()
+        if ($this.resources) {
+            $resourceObjects = @($this.resources | ForEach-Object {
                 [string[]]$excludeProps = @('_inDesiredState')
                 if ($null -eq $_._metadata) { $excludeProps += '_metadata' }
                 $_ | Select-Object -ExcludeProperty $excludeProps
             })
-        } else { @() }
+        }
         $retVal = [ordered]@{
             repositoryName = $this.repositoryName
-            resources      = [object[]]$resourceObjects
+            resources      = $resourceObjects
         } | ConvertTo-Json -Compress -Depth 5 -EnumsAsStrings
         Write-Trace -message "Serializing PSResourceList to JSON. RepositoryName: $($this.repositoryName), TrustedRepository: $($this.trustedRepository), Resources count: $($this.resources.Count)" -level debug
         Write-Trace -message "Serialized JSON: $retVal" -level trace
@@ -179,16 +181,17 @@ class PSResourceList {
 
     [string] ToJsonForTest() {
         Write-Trace -message "Serializing PSResourceList to JSON for test output. RepositoryName: $($this.repositoryName), TrustedRepository: $($this.trustedRepository), Resources count: $($this.resources.Count)" -level debug
-        $resourceObjects = if ($this.resources) {
-            @($this.resources | ForEach-Object {
+        [object[]]$resourceObjects = @()
+        if ($this.resources) {
+            $resourceObjects = @($this.resources | ForEach-Object {
                 [string[]]$excludeProps = @()
                 if ($null -eq $_._metadata) { $excludeProps += '_metadata' }
                 if ($excludeProps.Count -gt 0) { $_ | Select-Object -ExcludeProperty $excludeProps } else { $_ }
             })
-        } else { @() }
+        }
         $retVal = [ordered]@{
             repositoryName    = $this.repositoryName
-            resources         = [object[]]$resourceObjects
+            resources         = $resourceObjects
             trustedRepository = $this.trustedRepository
             _inDesiredState   = $this._inDesiredState
         } | ConvertTo-Json -Compress -Depth 5 -EnumsAsStrings
@@ -385,6 +388,12 @@ function GetPSResourceList {
                         }
                     }
                 }
+                elseif (-not ($resourcesExist | Where-Object { $_.Name -eq $resource.Name })) {
+                    # No version constraint: any installed version means the resource exists.
+                    # Only record the first match so that one input resource maps to one current resource.
+                    Write-Trace -message "No version constraint for input: $($inputResource.Name). Treating installed version $($resource.Version) as a match." -level debug
+                    $resourcesExist += $resource
+                }
             }
         }
     }
@@ -613,6 +622,22 @@ function WhatIfPSResourceList {
         }
     }
 
+    ## Report the same failures a real set operation would hit before installing anything
+    $installRequired = @($projectedResources | Where-Object { $_._exist -and $null -ne $_._metadata }).Count -gt 0
+    if ($installRequired) {
+        $psRepository = Get-PSResourceRepository -Name $repositoryName -ErrorAction SilentlyContinue
+
+        if (-not $psRepository) {
+            Write-Trace -level error -message "Repository '$repositoryName' not found. Cannot install resources."
+            exit [ExitCode]::RepositoryNotFound
+        }
+
+        if (-not $psRepository.Trusted -and -not $inputObj.trustedRepository) {
+            Write-Trace -level error -message "Repository '$repositoryName' is not trusted. Cannot install resources."
+            exit [ExitCode]::RepositoryNotTrusted
+        }
+    }
+
     $list = [PSResourceList]::new($repositoryName, $projectedResources, $currentState.trustedRepository)
     $list.ToJson()
 }

src/dsc/psresourcelist.dsc.resource.json

@@ -32,12 +32,24 @@
       "-ExecutionPolicy",
       "Bypass",
       "-Command",
-      "$Input | ./psresourceget.ps1 -resourcetype 'psresourcelist' -operation set",
-      { "whatIfArg": "-WhatIf" }
+      "$Input | ./psresourceget.ps1 -resourcetype 'psresourcelist' -operation set; exit $LASTEXITCODE"
     ],
     "input": "stdin",
-    "return": "stateAndDiff",
-    "whatIfReturns": "state"
+    "return": "stateAndDiff"
+  },
+  "whatIf": {
+    "executable": "pwsh",
+    "args": [
+      "-NoLogo",
+      "-NonInteractive",
+      "-NoProfile",
+      "-ExecutionPolicy",
+      "Bypass",
+      "-Command",
+      "$Input | ./psresourceget.ps1 -resourcetype 'psresourcelist' -operation set -WhatIf; exit $LASTEXITCODE"
+    ],
+    "input": "stdin",
+    "return": "state"
   },
   "export": {
     "executable": "pwsh",