feat: support dependentSchemas

Author: kylef

Sources/Draft201909Validator.swift

@@ -21,6 +21,7 @@ public class Draft201909Validator: Validator {
     "const": const,
     "format": format,
     "dependencies": dependencies,
+    "dependentSchemas": dependentSchemas,
     "allOf": allOf,
     "oneOf": oneOf,
     "anyOf": anyOf,

Sources/Validators.swift

@@ -560,6 +560,23 @@ func dependentRequired(validator: Validator, dependentRequired: Any, instance: A
   }))
 }
 
+func dependentSchemas(validator: Validator, dependentRequired: Any, instance: Any, schema: [String: Any]) -> ValidationResult {
+  guard let instance = instance as? [String: Any] else {
+    return .valid
+  }
+
+  guard let dependentRequired = dependentRequired as? [String: Any] else {
+    return .valid
+  }
+
+  return flatten(dependentRequired.compactMap({ (key, subschema) -> ValidationResult? in
+    if instance.keys.contains(key) {
+      return validator.descend(instance: instance, subschema: subschema)
+    }
+
+    return nil
+  }))
+}
 
 func propertyNames(validator: Validator, propertyNames: Any, instance: Any, schema: [String: Any]) -> ValidationResult {
   guard let instance = instance as? [String: Any] else {

Tests/JSONSchemaTests/JSONSchemaCases.swift

@@ -123,7 +123,6 @@ class JSONSchemaCases: XCTestCase {
       "ref.json",
       "refRemote.json",
       "anchor.json",
-      "dependentSchemas.json",
       "unevaluatedProperties.json",
       "unevaluatedItems.json",