Distinguish ordered maps in conformance

Co-authored-by: Copilot App <223556219+Copilot@users.noreply.github.com>

Author: MariusStorhaug

tests/Conformance.Tests.ps1

@@ -167,6 +167,9 @@ Describe 'Released yaml-test-suite corpus accounting' {
         $firstOrder.Add('b', 2)
         $secondOrder.Add('b', 2)
         $secondOrder.Add('a', 1)
+        $ordinarySameOrder = [System.Collections.Specialized.OrderedDictionary]::new()
+        $ordinarySameOrder.Add('a', 1)
+        $ordinarySameOrder.Add('b', 2)
         (ConvertTo-YamlSuiteCanonicalValue -Value $firstOrder) |
             Should -Be (ConvertTo-YamlSuiteCanonicalValue -Value $secondOrder)
 
@@ -181,6 +184,12 @@ Describe 'Released yaml-test-suite corpus accounting' {
                 ConvertTo-YamlSuiteCanonicalValue -Value $secondOrder `
                     -OrderedMappings $orderedMappings
             )
+        (ConvertTo-YamlSuiteCanonicalValue -Value $firstOrder `
+            -OrderedMappings $orderedMappings) |
+            Should -Not -Be (
+                ConvertTo-YamlSuiteCanonicalValue -Value $ordinarySameOrder `
+                    -OrderedMappings $orderedMappings
+            )
 
         $firstNestedKey = [System.Collections.Specialized.OrderedDictionary]::new()
         $secondNestedKey = [System.Collections.Specialized.OrderedDictionary]::new()
@@ -272,6 +281,30 @@ ship-to:
         $ordinaryResult.OutYamlResult | Should -Be 'Pass'
     }
 
+    It 'detects explicit ordered-map tag loss across representation surfaces' {
+        $tagLossSuitePath = Join-Path $TestDrive 'ordered-map-tag-loss'
+        $tagLossCasePath = Join-Path $tagLossSuitePath 'omap-tag-loss'
+        $null = New-Item -Path $tagLossCasePath -ItemType Directory -Force
+        "!!omap`n- a: 1`n- b: 2" |
+            Set-Content -LiteralPath (Join-Path $tagLossCasePath 'in.yaml') `
+                -Encoding utf8NoBOM
+        foreach ($fixture in @('out.yaml', 'emit.yaml')) {
+            "a: 1`nb: 2" |
+                Set-Content -LiteralPath (Join-Path $tagLossCasePath $fixture) `
+                    -Encoding utf8NoBOM
+        }
+
+        $tagLossResult = & $runnerPath -Path $tagLossSuitePath `
+            -CompareOutYaml -CompareEmitYaml -CompareSelfRoundTrip
+
+        $tagLossResult.OutYamlResult | Should -Be 'Fail'
+        $tagLossResult.OutYamlReason | Should -Be 'OutYamlConstructionMismatch'
+        $tagLossResult.EmitYamlResult | Should -Be 'Fail'
+        $tagLossResult.EmitYamlReason | Should -Be 'EmitYamlRepresentationMismatch'
+        $tagLossResult.SelfRoundTripResult | Should -Be 'PolicyDifference'
+        $tagLossResult.SelfRoundTripReason | Should -Be 'LegacyOrderedMapProjection'
+    }
+
     It 'accounts for out.yaml representation comparisons' {
         @($suiteResults | Where-Object OutYamlResult -EQ 'Pass').Count | Should -Be 241
         @($suiteResults | Where-Object OutYamlResult -EQ 'PolicyDifference').Count |

tests/tools/Invoke-YamlTestSuite.ps1

@@ -199,7 +199,8 @@ function ConvertTo-YamlSuiteCanonicalValue {
         if ($SortMappings -or -not $isOrdered) {
             $entries.Sort([System.StringComparer]::Ordinal)
         }
-        return 'map:{0}:{{{1}}}' -f $entries.Count, ($entries -join '|')
+        $mappingKind = if ($isOrdered) { 'omap' } else { 'map' }
+        return '{0}:{1}:{{{2}}}' -f $mappingKind, $entries.Count, ($entries -join '|')
     }
     if ($Value -is [System.Collections.IEnumerable] -and $Value -isnot [string]) {
         $items = [System.Collections.Generic.List[string]]::new()