Use JSON Schema defaults in synthetic test get_diff

dsc/tests/dsc_schema_default.tests.ps1

@@ -0,0 +1,54 @@
+# Copyright (c) Microsoft Corporation.
+# Licensed under the MIT License.
+
+Describe 'Synthetic test uses schema defaults' {
+    It 'Property matching schema default is not reported as differing' {
+        $out = '{"name":"test","enabled":true}' | dsc resource test -r Test/SchemaDefault -f - | ConvertFrom-Json
+        $LASTEXITCODE | Should -Be 0
+        $out.inDesiredState | Should -Be $true
+        $out.differingProperties | Should -BeNullOrEmpty
+    }
+
+    It 'Property differing from schema default is reported as differing' {
+        $out = '{"name":"test","enabled":false}' | dsc resource test -r Test/SchemaDefault -f - | ConvertFrom-Json
+        $LASTEXITCODE | Should -Be 0
+        $out.inDesiredState | Should -Be $false
+        $out.differingProperties | Should -Contain 'enabled'
+    }
+
+    It 'Integer property matching schema default is not reported as differing' {
+        $out = '{"name":"test","count":5}' | dsc resource test -r Test/SchemaDefault -f - | ConvertFrom-Json
+        $LASTEXITCODE | Should -Be 0
+        $out.inDesiredState | Should -Be $true
+        $out.differingProperties | Should -BeNullOrEmpty
+    }
+
+    It 'Integer property differing from schema default is reported as differing' {
+        $out = '{"name":"test","count":10}' | dsc resource test -r Test/SchemaDefault -f - | ConvertFrom-Json
+        $LASTEXITCODE | Should -Be 0
+        $out.inDesiredState | Should -Be $false
+        $out.differingProperties | Should -Contain 'count'
+    }
+
+    It 'Multiple properties matching schema defaults are not reported as differing' {
+        $out = '{"name":"test","enabled":true,"count":5}' | dsc resource test -r Test/SchemaDefault -f - | ConvertFrom-Json
+        $LASTEXITCODE | Should -Be 0
+        $out.inDesiredState | Should -Be $true
+        $out.differingProperties | Should -BeNullOrEmpty
+    }
+
+    It 'Mix of matching and non-matching defaults reports only non-matching' {
+        $out = '{"name":"test","enabled":true,"count":10}' | dsc resource test -r Test/SchemaDefault -f - | ConvertFrom-Json
+        $LASTEXITCODE | Should -Be 0
+        $out.inDesiredState | Should -Be $false
+        $out.differingProperties | Should -Contain 'count'
+        $out.differingProperties | Should -Not -Contain 'enabled'
+    }
+
+    It 'Property present in both expected and actual is compared normally' {
+        $out = '{"name":"test"}' | dsc resource test -r Test/SchemaDefault -f - | ConvertFrom-Json
+        $LASTEXITCODE | Should -Be 0
+        $out.inDesiredState | Should -Be $true
+        $out.differingProperties | Should -BeNullOrEmpty
+    }
+}

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

@@ -12,7 +12,7 @@ use crate::{configure::{config_doc::{ExecutionKind, SecurityContextKind}, config
 use crate::dscerror::DscError;
 use crate::locked_insert;
 use super::{
-    dscresource::{get_diff, redact, DscResource},
+    dscresource::{get_diff, get_diff_with_schema, redact, DscResource},
     invoke_result::{
         DeleteResult, DeleteResultKind, ExportResult,
         GetResult, ResolveResult, SetResult, TestResult, ValidateResult,
@@ -454,7 +454,14 @@ fn invoke_synthetic_test(resource: &DscResource, expected: &str, target_resource
         }
     };
     let expected_value: Value = serde_json::from_str(expected)?;
-    let diff_properties = get_diff(&expected_value, &actual_state);
+    let cached_resource = target_resource.unwrap_or(resource);
+    let schema: Option<Value> = get_resource_schema(&cached_resource.type_name, &cached_resource.version)
+        .or_else(|| {
+            // Populate the cache on a miss, then read from cache
+            get_schema(resource, target_resource).ok();
+            get_resource_schema(&cached_resource.type_name, &cached_resource.version)
+        });
+    let diff_properties = get_diff_with_schema(&expected_value, &actual_state, schema.as_ref());
     Ok(TestResult::Resource(ResourceTestResponse {
         desired_state: expected_value,
         actual_state,

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

@@ -470,7 +470,12 @@ impl Invoke for DscResource {
                             response.actual_state
                         }
                     };
-                    let diff_properties = get_diff( &desired_state, &actual_state);
+                    let schema: Option<Value> = if let Some(s) = &self.schema {
+                        serde_json::to_value(s).ok()
+                    } else {
+                        self.schema().ok().and_then(|s| serde_json::from_str(&s).ok())
+                    };
+                    let diff_properties = get_diff_with_schema( &desired_state, &actual_state, schema.as_ref());
                     desired_state = redact(&desired_state);
                     let test_result = TestResult::Resource(ResourceTestResponse {
                         desired_state,
@@ -647,6 +652,24 @@ pub fn get_adapter_input_kind(adapter: &DscResource) -> Result<AdapterInputKind,
 ///
 /// An array of top level properties that differ, if any
 pub fn get_diff(expected: &Value, actual: &Value) -> Vec<String> {
+    get_diff_with_schema(expected, actual, None)
+}
+
+#[must_use]
+/// Performs a comparison of two JSON Values using an optional JSON Schema.
+/// If a property exists in `expected` but not in `actual`, the schema's `default` value
+/// for that property is used for comparison when available.
+///
+/// # Arguments
+///
+/// * `expected` - The expected value
+/// * `actual` - The actual value
+/// * `schema` - Optional JSON Schema to look up default values for missing properties
+///
+/// # Returns
+///
+/// An array of top level properties that differ, if any
+pub(crate) fn get_diff_with_schema(expected: &Value, actual: &Value, schema: Option<&Value>) -> Vec<String> {
     let mut diff_properties: Vec<String> = Vec::new();
     if expected.is_null() {
         return diff_properties;
@@ -702,8 +725,17 @@ pub fn get_diff(expected: &Value, actual: &Value) -> Vec<String> {
                             diff_properties.push(key.to_string());
                         }
                     } else {
-                        info!("{}", t!("dscresources.dscresource.diffKeyMissing", key = key));
-                        diff_properties.push(key.to_string());
+                        // Property not in actual - check schema for a default value
+                        let schema_default = get_schema_default(schema, key);
+                        if let Some(default_value) = schema_default {
+                            if value != &default_value {
+                                info!("{}", t!("dscresources.dscresource.diffKeyMissing", key = key));
+                                diff_properties.push(key.to_string());
+                            }
+                        } else {
+                            info!("{}", t!("dscresources.dscresource.diffKeyMissing", key = key));
+                            diff_properties.push(key.to_string());
+                        }
                     }
                 } else {
                     info!("{}", t!("dscresources.dscresource.diffKeyNotObject", key = key));
@@ -716,6 +748,23 @@ pub fn get_diff(expected: &Value, actual: &Value) -> Vec<String> {
     diff_properties
 }
 
+/// Looks up the default value for a property from a JSON Schema.
+///
+/// # Arguments
+///
+/// * `schema` - Optional JSON Schema value
+/// * `property_name` - The property name to look up
+///
+/// # Returns
+///
+/// The default value if found in the schema's properties definition, otherwise None
+fn get_schema_default(schema: Option<&Value>, property_name: &str) -> Option<Value> {
+    let schema = schema?;
+    let properties = schema.get("properties")?.as_object()?;
+    let property_schema = properties.get(property_name)?.as_object()?;
+    property_schema.get("default").cloned()
+}
+
 /// Validates the properties of a resource against its schema.
 ///
 /// # Arguments
@@ -926,3 +975,76 @@ fn different_array_with_nested_array() {
     let array_two = vec![json!("a"), json!(1), json!({"a":"b"}), json!(vec![json!("a"), json!(2)])];
     assert_eq!(is_same_array(&array_one, &array_two), false);
 }
+
+#[test]
+fn diff_with_schema_default_matches_expected() {
+    use serde_json::json;
+    let expected = json!({"name": "test", "enabled": true});
+    let actual = json!({"name": "test"});
+    let schema = json!({
+        "type": "object",
+        "properties": {
+            "name": { "type": "string" },
+            "enabled": { "type": "boolean", "default": true }
+        }
+    });
+    let diff = get_diff_with_schema(&expected, &actual, Some(&schema));
+    assert!(diff.is_empty(), "Expected no diff when expected matches schema default, got: {diff:?}");
+}
+
+#[test]
+fn diff_with_schema_default_differs_from_expected() {
+    use serde_json::json;
+    let expected = json!({"name": "test", "enabled": false});
+    let actual = json!({"name": "test"});
+    let schema = json!({
+        "type": "object",
+        "properties": {
+            "name": { "type": "string" },
+            "enabled": { "type": "boolean", "default": true }
+        }
+    });
+    let diff = get_diff_with_schema(&expected, &actual, Some(&schema));
+    assert_eq!(diff, vec!["enabled".to_string()]);
+}
+
+#[test]
+fn diff_with_schema_no_default_reports_missing_property() {
+    use serde_json::json;
+    let expected = json!({"name": "test", "enabled": true});
+    let actual = json!({"name": "test"});
+    let schema = json!({
+        "type": "object",
+        "properties": {
+            "name": { "type": "string" },
+            "enabled": { "type": "boolean" }
+        }
+    });
+    let diff = get_diff_with_schema(&expected, &actual, Some(&schema));
+    assert_eq!(diff, vec!["enabled".to_string()]);
+}
+
+#[test]
+fn diff_without_schema_reports_missing_property() {
+    use serde_json::json;
+    let expected = json!({"name": "test", "enabled": true});
+    let actual = json!({"name": "test"});
+    let diff = get_diff_with_schema(&expected, &actual, None);
+    assert_eq!(diff, vec!["enabled".to_string()]);
+}
+
+#[test]
+fn diff_with_schema_default_integer() {
+    use serde_json::json;
+    let expected = json!({"name": "test", "count": 5});
+    let actual = json!({"name": "test"});
+    let schema = json!({
+        "type": "object",
+        "properties": {
+            "name": { "type": "string" },
+            "count": { "type": "integer", "default": 5 }
+        }
+    });
+    let diff = get_diff_with_schema(&expected, &actual, Some(&schema));
+    assert!(diff.is_empty(), "Expected no diff when expected matches schema default integer, got: {diff:?}");
+}

resources/windows_firewall/tests/windows_firewall_schema_default.tests.ps1

@@ -0,0 +1,105 @@
+# Copyright (c) Microsoft Corporation.
+# Licensed under the MIT License.
+
+Describe 'Microsoft.Windows/FirewallRuleList - synthetic test with schema defaults' -Skip:(!$canRunFirewallTests) {
+    BeforeDiscovery {
+        $canRunFirewallTests = $IsWindows -and
+            (Get-Command Get-NetFirewallRule -ErrorAction Ignore) -and
+            ([Security.Principal.WindowsPrincipal][Security.Principal.WindowsIdentity]::GetCurrent()).IsInRole(
+                [Security.Principal.WindowsBuiltInRole]::Administrator)
+    }
+
+    BeforeAll {
+        $resourceType = 'Microsoft.Windows/FirewallRuleList'
+        $testRuleName = 'DSC-WindowsFirewall-SchemaDefault-Test'
+
+        # Ensure a known rule exists for testing
+        $existing = Get-NetFirewallRule -Name $testRuleName -ErrorAction Ignore
+        if (-not $existing) {
+            New-NetFirewallRule -Name $testRuleName -DisplayName $testRuleName `
+                -Direction Inbound -Action Allow -Protocol TCP -LocalPort 32921 `
+                -Enabled True -PolicyStore PersistentStore | Out-Null
+        }
+    }
+
+    AfterAll {
+        Remove-NetFirewallRule -Name $testRuleName -ErrorAction Ignore
+    }
+
+    It 'unspecifiedRulesAction set to default "ignore" does not report as differing' {
+        $json = @{
+            unspecifiedRulesAction = 'ignore'
+            rules = @(@{
+                name = $testRuleName
+                direction = 'Inbound'
+                action = 'Allow'
+                protocol = 6
+                localPorts = '32921'
+                enabled = $true
+            })
+        } | ConvertTo-Json -Compress -Depth 5
+        $out = $json | dsc resource test -r $resourceType -f - 2>$testdrive/error.log
+        $LASTEXITCODE | Should -Be 0 -Because (Get-Content -Raw $testdrive/error.log)
+
+        $result = $out | ConvertFrom-Json
+        $result.inDesiredState | Should -Be $true
+        $result.differingProperties | Should -Not -Contain 'unspecifiedRulesAction'
+    }
+
+    It 'unspecifiedRulesAction omitted does not report as differing' {
+        $json = @{
+            rules = @(@{
+                name = $testRuleName
+                direction = 'Inbound'
+                action = 'Allow'
+                protocol = 6
+                localPorts = '32921'
+                enabled = $true
+            })
+        } | ConvertTo-Json -Compress -Depth 5
+        $out = $json | dsc resource test -r $resourceType -f - 2>$testdrive/error.log
+        $LASTEXITCODE | Should -Be 0 -Because (Get-Content -Raw $testdrive/error.log)
+
+        $result = $out | ConvertFrom-Json
+        $result.inDesiredState | Should -Be $true
+        $result.differingProperties | Should -Not -Contain 'unspecifiedRulesAction'
+    }
+
+    It 'non-default unspecifiedRulesAction "disable" is reported as differing' {
+        $json = @{
+            unspecifiedRulesAction = 'disable'
+            rules = @(@{
+                name = $testRuleName
+                direction = 'Inbound'
+                action = 'Allow'
+                protocol = 6
+                localPorts = '32921'
+                enabled = $true
+            })
+        } | ConvertTo-Json -Compress -Depth 5
+        $out = $json | dsc resource test -r $resourceType -f - 2>$testdrive/error.log
+        $LASTEXITCODE | Should -Be 0 -Because (Get-Content -Raw $testdrive/error.log)
+
+        $result = $out | ConvertFrom-Json
+        $result.differingProperties | Should -Contain 'unspecifiedRulesAction'
+    }
+
+    It 'non-default unspecifiedRulesAction "remove" is reported as differing' {
+        $json = @{
+            unspecifiedRulesAction = 'remove'
+            rules = @(@{
+                name = $testRuleName
+                direction = 'Inbound'
+                action = 'Allow'
+                protocol = 6
+                localPorts = '32921'
+                enabled = $true
+            })
+        } | ConvertTo-Json -Compress -Depth 5
+        $out = $json | dsc resource test -r $resourceType -f - 2>$testdrive/error.log
+        $LASTEXITCODE | Should -Be 0 -Because (Get-Content -Raw $testdrive/error.log)
+
+        $result = $out | ConvertFrom-Json
+        $result.differingProperties | Should -Contain 'unspecifiedRulesAction'
+    }
+}

tools/dsctest/dsctest.dsc.manifests.json

@@ -280,6 +280,45 @@
         }
       }
     },
+    {
+      "$schema": "https://aka.ms/dsc/schemas/v3/bundled/resource/manifest.json",
+      "type": "Test/SchemaDefault",
+      "version": "0.1.0",
+      "get": {
+        "executable": "dsctest",
+        "args": [
+          "schema-default",
+          {
+            "jsonInputArg": "--input",
+            "mandatory": true
+          }
+        ]
+      },
+      "schema": {
+        "embedded": {
+          "$schema": "http://json-schema.org/draft-07/schema#",
+          "type": "object",
+          "required": ["name"],
+          "additionalProperties": false,
+          "properties": {
+            "name": {
+              "type": "string",
+              "description": "The name of the resource instance."
+            },
+            "enabled": {
+              "type": "boolean",
+              "description": "Whether the resource is enabled.",
+              "default": true
+            },
+            "count": {
+              "type": "integer",
+              "description": "The count value.",
+              "default": 5
+            }
+          }
+        }
+      }
+    },
     {
       "$schema": "https://aka.ms/dsc/schemas/v3/bundled/resource/manifest.json",
       "type": "Test/InDesiredState",