Add convenience function for "additionalProperties" schema result parsing

The JSON schema validation result parsing infrastructure provides general purpose capabilities for identifying the
instance and schema pointers related to a validation failure. However, when a specific type of schema keyword is used in
multiple places, it is convenient to create a dedicated wrapper function to facilitate that use case. Previously the
"additionalProperties" keyword was not used in any rules, which made it not worth a convenience function. The package
index schema uses the "additionalProperties" keyword, so it now becomes worthwhile having a
convenience parsing function for it.

Author: per1234

Diff for: internal/rule/schema/parsevalidationresult.go

@@ -64,6 +64,11 @@ func PropertyFormatMismatch(propertyName string, validationResult ValidationResu
 	return ValidationErrorMatch("^#/"+propertyName+"$", "/format$", "", "", validationResult)
 }
 
+// ProhibitedAdditionalProperty returns whether the given property has prohibited additional subproperty(s).
+func ProhibitedAdditionalProperties(propertyName string, validationResult ValidationResult) bool {
+	return ValidationErrorMatch("^#/?"+propertyName+"$", "/additionalProperties$", "", "", validationResult)
+}
+
 // MisspelledOptionalPropertyFound returns whether a misspelled optional property was found.
 func MisspelledOptionalPropertyFound(validationResult ValidationResult) bool {
 	return ValidationErrorMatch("#/", "/misspelledOptionalProperties/", "", "", validationResult)

Diff for: internal/rule/schema/schema_test.go

@@ -19,6 +19,7 @@ import (
 	"encoding/json"
 	"fmt"
 	"regexp"
+	"strings"
 	"testing"
 
 	"github.com/arduino/arduino-lint/internal/project/general"
@@ -199,6 +200,48 @@ func TestPropertyFormatMismatch(t *testing.T) {
 	assert.True(t, PropertyFormatMismatch(propertyName, Validate(instance, validSchemaWithReferences)), "Property format is incorrect")
 }
 
+func TestProhibitedAdditionalProperties(t *testing.T) {
+	propertyName := "TestProhibitedAdditionalProperties"
+	instanceTemplate := `
+{
+	"%s": {
+		"additionalPropertiesTrue": {
+			"fooProperty": "bar"
+		},
+		"additionalPropertiesFalse": {
+			"fooProperty": "bar"
+		}
+	}
+}
+`
+
+	testTables := []struct {
+		objectPointerString string
+		assertion           assert.BoolAssertionFunc
+	}{
+		{"/TestProhibitedAdditionalProperties/additionalPropertiesTrue", assert.False},
+		{"/TestProhibitedAdditionalProperties/additionalPropertiesFalse", assert.True},
+	}
+
+	for _, testTable := range testTables {
+		rawInstance := fmt.Sprintf(instanceTemplate, propertyName)
+		var instance map[string]interface{}
+		json.Unmarshal([]byte(rawInstance), &instance)
+
+		assert.False(t, ProhibitedAdditionalProperties(strings.TrimPrefix(testTable.objectPointerString, "/"), Validate(instance, validSchemaWithReferences)), fmt.Sprintf("No additional properties in %s", testTable.objectPointerString))
+
+		// Add additional property to object.
+		pointer, err := gojsonpointer.NewJsonPointer(testTable.objectPointerString + "/fooAdditionalProperty")
+		require.NoError(t, err)
+		_, err = pointer.Set(instance, "bar")
+		require.NoError(t, err)
+
+		t.Run(fmt.Sprintf("Additional property in the %s object", testTable.objectPointerString), func(t *testing.T) {
+			testTable.assertion(t, ProhibitedAdditionalProperties(strings.TrimPrefix(testTable.objectPointerString, "/"), Validate(instance, validSchemaWithReferences)))
+		})
+	}
+}
+
 func TestPropertyDependenciesMissing(t *testing.T) {
 	propertiesMap := properties.NewFromHashmap(validMap)
 	validationResult := Validate(general.PropertiesToMap(propertiesMap, 0), validSchemaWithReferences)

Diff for: internal/rule/schema/testdata/bindata.go

@@ -241,6 +241,22 @@ var _validSchemaWithReferencesJson = []byte(`{
           "$ref": "referenced-schema-2.json#/definitions/TestPropertyFormatMismatch/object"
         }
       ]
+    },
+    "TestProhibitedAdditionalProperties": {
+      "properties": {
+        "additionalPropertiesTrue": {
+          "properties": {
+            "fooProperty": {}
+          },
+          "additionalProperties": true
+        },
+        "additionalPropertiesFalse": {
+          "properties": {
+            "fooProperty": {}
+          },
+          "additionalProperties": false
+        }
+      }
     }
   },
   "allOf": [

Diff for: internal/rule/schema/testdata/input/valid-schema-with-references.json

@@ -44,6 +44,22 @@
           "$ref": "referenced-schema-2.json#/definitions/TestPropertyFormatMismatch/object"
         }
       ]
+    },
+    "TestProhibitedAdditionalProperties": {
+      "properties": {
+        "additionalPropertiesTrue": {
+          "properties": {
+            "fooProperty": {}
+          },
+          "additionalProperties": true
+        },
+        "additionalPropertiesFalse": {
+          "properties": {
+            "fooProperty": {}
+          },
+          "additionalProperties": false
+        }
+      }
     }
   },
   "allOf": [