feat: implement export filter functionality for resource exports

dsc/tests/dsc_export.tests.ps1

@@ -213,3 +213,53 @@ resources:
       $out.resources[0].properties.id | Should -Be 1
     }
 }
+
+Describe 'engine export filtering tests' {
+    It 'engine filters properties for a resource that does not support filtering natively' {
+        $yaml = @'
+$schema: https://aka.ms/dsc/schemas/v3/bundled/config/document.json
+resources:
+- name: No Native Filtering
+  type: Test/ExportSchemaNoFiltering
+  properties:
+    name: '*e*'
+'@
+        $out = dsc --trace-level info config export -i $yaml 2>$TESTDRIVE/error.log | ConvertFrom-Json
+        $errorlog = Get-Content "$TESTDRIVE/error.log" -Raw
+        $LASTEXITCODE | Should -Be 0 -Because $errorlog
+        @($out.resources).Count | Should -Be 2
+        $out.resources.properties.name | Should -Be @('Steve', 'Tess')
+        $errorlog | Should -Match 'does not support export filtering, the engine will filter the exported instances'
+    }
+
+    It 'INFO message indicates engine export filtering is experimental' {
+        $yaml = @'
+$schema: https://aka.ms/dsc/schemas/v3/bundled/config/document.json
+resources:
+- name: No Native Filtering
+  type: Test/ExportSchemaNoFiltering
+  properties:
+    name: 'Gijs'
+'@
+        $out = dsc --trace-level info config export -i $yaml 2>$TESTDRIVE/error.log | ConvertFrom-Json
+        $errorlog = Get-Content "$TESTDRIVE/error.log" -Raw
+        $LASTEXITCODE | Should -Be 0 -Because $errorlog
+        @($out.resources).Count | Should -Be 1
+        $out.resources[0].properties.name | Should -BeExactly 'Gijs'
+        $errorlog | Should -Match 'experimental'
+    }
+
+    It 'no INFO message is emitted when no filter input is provided' {
+        $yaml = @'
+$schema: https://aka.ms/dsc/schemas/v3/bundled/config/document.json
+resources:
+- name: No Native Filtering
+  type: Test/ExportSchemaNoFiltering
+'@
+        $out = dsc --trace-level info config export -i $yaml 2>$TESTDRIVE/error.log | ConvertFrom-Json
+        $errorlog = Get-Content "$TESTDRIVE/error.log" -Raw
+        $LASTEXITCODE | Should -Be 0 -Because $errorlog
+        @($out.resources).Count | Should -Be 3
+        $errorlog | Should -Not -Match 'the engine will filter the exported instances'
+    }
+}

dsc/tests/dsc_resource_export.tests.ps1

@@ -17,13 +17,29 @@ Describe 'Resource export tests' {
         $output.resources.properties.name | Should -Be $expected -Because ($output | ConvertTo-Json -Depth 4)
     }
 
-    It 'Resource not support export filtering will return error' {
+    It "Engine filters input '<json>' for a resource without native filtering support" -TestCases @(
+        @{ json = '{ "name": "Gijs" }'; expected = @('Gijs') }
+        @{ json = '{ "name": "*e*" }'; expected = @('Steve', 'Tess') }
+        @{ json = '[{ "name": "Gijs" }, { "name": "Steve" }]'; expected = @('Steve', 'Gijs') }
+    ){
+        param($json, $expected)
+
+        $resource = 'Test/ExportSchemaNoFiltering'
+        $output = dsc --trace-level info resource export -r $resource -i $json 2>$TESTDRIVE/error.log | ConvertFrom-Json
+        $errorlog = Get-Content "$TESTDRIVE/error.log" -Raw
+        $LASTEXITCODE | Should -Be 0 -Because $errorlog
+        $output.resources.count | Should -Be $expected.Count -Because ($output | ConvertTo-Json -Depth 4)
+        $output.resources.properties.name | Should -Be $expected -Because ($output | ConvertTo-Json -Depth 4)
+        $errorlog | Should -Match "Resource '$resource' does not support export filtering, the engine will filter the exported instances \(experimental feature\)"
+    }
+
+    It 'Engine filtering rejects input that is not an object or array of objects' {
         $resource = 'Test/ExportSchemaNoFiltering'
-        $json = '{ "name": "Gijs" }'
+        $json = '5'
 
-        $output = dsc resource export -r $resource -i $json  2>$TESTDRIVE/error.log | ConvertFrom-Json
+        dsc resource export -r $resource -i $json 2>$TESTDRIVE/error.log | Out-Null
         $errorlog = Get-Content "$TESTDRIVE/error.log" -Raw
         $LASTEXITCODE | Should -Be 2 -Because $errorlog
-        $errorlog | Should -Match "Resource '$resource' does not support export filtering"
+        $errorlog | Should -Match 'Export filter input must be a JSON object or an array of JSON objects'
     }
 }

helpers.build.psm1

@@ -2448,6 +2448,8 @@ function Get-CodeCoverageReport {
                     $currentLineNum++
                 } elseif ($diffLine.StartsWith('-') -and -not $diffLine.StartsWith('---')) {
                     # Deleted lines don't advance the new file line counter
+                } elseif ($diffLine.StartsWith('\')) {
+                    # "\ No newline at end of file" marker — not a real line
                 } else {
                     $currentLineNum++
                 }
@@ -2469,10 +2471,7 @@ function Get-CodeCoverageReport {
             }
 
             if (-not $fileCoverage) {
-                # File not in coverage report means LLVM found no instrumentable
-                # executable code in it (e.g., struct/enum definitions with derive
-                # macros). Skip it rather than penalizing as uncovered.
-                Write-Verbose -Verbose "No LCOV data for '$file' - file has no instrumentable code, skipping"
+                Write-Verbose -Verbose "Skipping '$file': not in LCOV data (possibly platform-specific or not instrumented)"
                 continue
             }
 

lib/dsc-lib/locales/en-us.toml

@@ -35,6 +35,9 @@ dependencyNotInOrder = "Dependency not found in order"
 circularDependency = "Circular dependency detected for resource named '%{resource}'"
 invocationOrder = "Resource invocation order"
 
+[configure.export_filter]
+filteredInstances = "Export filter reduced %{original} instances to %{retained}"
+
 [configure.mod]
 nestedArraysNotSupported = "Nested arrays not supported"
 arrayElementCouldNotTransformAsString = "Array element could not be transformed as string"
@@ -48,6 +51,9 @@ groupNotSupportedForDelete = "Group resources not supported for delete"
 deleteNotSupported = "Resource '%{resource}' does not support `delete` and does not handle `_exist` as false"
 expectedState = "Expected state: %{state}"
 exportInput = "Export input: %{input}"
+engineExportFiltering = "Resource '%{resource}' does not support export filtering, the engine will filter the exported instances (experimental feature)"
+invalidExportFilterInput = "Invalid export filter input: %{error}"
+exportFilterNotObject = "Export filter input must be a JSON object or an array of JSON objects"
 noParameters = "No parameters defined in configuration and no parameters input"
 noParametersDefined = "No parameters defined in configuration"
 processingParameter = "Processing parameter '%{name}'"