feat: support dependentRequired

Author: kylef

Sources/Draft201909Validator.swift

@@ -10,6 +10,7 @@ public class Draft201909Validator: Validator {
     "$ref": ref,
     "type": type,
     "required": required,
+    "dependentRequired": dependentRequired,
     "propertyNames": propertyNames,
     "not": not,
     "pattern": pattern,

Sources/Validators.swift

@@ -542,6 +542,25 @@ func required(validator: Validator, required: Any, instance: Any, schema: [Strin
   return .invalid(["Required properties are missing '\(required)'"])
 }
 
+func dependentRequired(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: [String]] else {
+    return .valid
+  }
+
+  return flatten(dependentRequired.compactMap({ (key, required) -> ValidationResult? in
+    if instance.keys.contains(key) {
+      return JSONSchema.required(validator: validator, required: required, instance: instance, schema: schema)
+    }
+
+    return nil
+  }))
+}
+
+
 func propertyNames(validator: Validator, propertyNames: Any, instance: Any, schema: [String: Any]) -> ValidationResult {
   guard let instance = instance as? [String: Any] else {
     return .valid

Tests/JSONSchemaTests/JSONSchemaCases.swift

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