feat: combine multipleOf errors into a single message

src/error-handlers/multipleOf.js

@@ -11,6 +11,11 @@ const multipleOfErrorHandler = async (normalizedErrors, instance, localization)
   /** @type ErrorObject[] */
   const errors = [];
 
+  /** @type (number | null) */
+  let combinedMultipleOf = null;
+  /** @type string[] */
+  const schemaLocations = [];
+
   for (const schemaLocation in normalizedErrors["https://json-schema.org/keyword/multipleOf"]) {
     if (normalizedErrors["https://json-schema.org/keyword/multipleOf"][schemaLocation]) {
       continue;
@@ -19,14 +24,42 @@ const multipleOfErrorHandler = async (normalizedErrors, instance, localization)
     const keyword = await getSchema(schemaLocation);
     const multipleOf = /** @type number */ (Schema.value(keyword));
 
+    combinedMultipleOf = combinedMultipleOf === null ? multipleOf : lcm(combinedMultipleOf, multipleOf);
+    schemaLocations.push(schemaLocation);
+  }
+
+  if (combinedMultipleOf !== null) {
     errors.push({
-      message: localization.getMultipleOfErrorMessage(multipleOf),
+      message: localization.getMultipleOfErrorMessage(combinedMultipleOf),
       instanceLocation: Instance.uri(instance),
-      schemaLocations: [schemaLocation]
+      schemaLocations
     });
   }
 
   return errors;
 };
 
+/**
+ * @param {number} a
+ * @param {number} b
+ * @returns {number}
+ */
+const gcd = (a, b) => {
+  while (b !== 0) {
+    const temp = b;
+    b = a % b;
+    a = temp;
+  }
+  return Math.abs(a);
+};
+
+/**
+ * @param {number} a
+ * @param {number} b
+ * @returns {number}
+ */
+const lcm = (a, b) => {
+  return Math.abs(a * b) / gcd(a, b);
+};
+
 export default multipleOfErrorHandler;

src/test-suite/tests/multipleOf.json

@@ -25,6 +25,24 @@
       },
       "instance": 6,
       "errors": []
+    },
+    {
+      "description": "multiple multipleOf constraints (LCM of 3 and 2)",
+      "schema": {
+        "allOf": [
+          { "multipleOf": 3 },
+          { "multipleOf": 2 }
+        ]
+      },
+      "instance": 5,
+      "errors": [
+        {
+          "messageId": "multipleOf-message",
+          "messageParams": { "multipleOf": "6" },
+          "instanceLocation": "#",
+          "schemaLocations": ["#/allOf/0/multipleOf", "#/allOf/1/multipleOf"]
+        }
+      ]
     }
   ]
 }