throwing SchemaException if multipleOf is 0 - fixes #426

Author: Bence Erős

core/src/main/java/org/everit/json/schema/loader/SchemaExtractor.java

@@ -9,6 +9,7 @@
 import static org.everit.json.schema.loader.SpecificationVersion.DRAFT_4;
 import static org.everit.json.schema.loader.SpecificationVersion.DRAFT_7;
 
+import java.math.BigDecimal;
 import java.util.ArrayList;
 import java.util.Collection;
 import java.util.HashSet;
@@ -148,7 +149,12 @@ NumberSchema.Builder buildNumberSchema() {
         NumberSchema.Builder builder = NumberSchema.builder();
         maybe("minimum").map(JsonValue::requireNumber).ifPresent(builder::minimum);
         maybe("maximum").map(JsonValue::requireNumber).ifPresent(builder::maximum);
-        maybe("multipleOf").map(JsonValue::requireNumber).ifPresent(builder::multipleOf);
+        maybe("multipleOf").map(JsonValue::requireNumber).ifPresent(multipleOf -> {
+            if (BigDecimal.ZERO.compareTo(BigDecimal.valueOf(multipleOf.doubleValue())) == 0) {
+                throw new SchemaException(schemaJson.ls.locationOfCurrentObj(), "multipleOf should not be 0");
+            }
+            builder.multipleOf(multipleOf);
+        });
         maybe("exclusiveMinimum").ifPresent(exclMin -> exclusiveLimitHandler.handleExclusiveMinimum(exclMin, builder));
         maybe("exclusiveMaximum").ifPresent(exclMax -> exclusiveLimitHandler.handleExclusiveMaximum(exclMax, builder));
         return builder;

core/src/test/java/org/everit/json/schema/loader/SchemaLoaderTest.java

@@ -340,6 +340,14 @@ public void pointerResolutionQueryFailure() {
         });
     }
 
+    @Test
+    void multipleOfShouldNotBeZero() {
+        SchemaException thrown = Assertions.assertThrows(SchemaException.class, () -> {
+            SchemaLoader.load(get("multipleOfShouldNotBeZero"));
+        });
+        assertEquals("#: multipleOf should not be 0", thrown.getMessage());
+    }
+
     @Test @Disabled
     public void propsAroundRefExtendTheReferredSchema() {
         ObjectSchema actual = (ObjectSchema) SchemaLoader

core/src/test/resources/org/everit/jsonvalidator/testschemas.json

@@ -730,5 +730,8 @@
         }
       }
     }
+  },
+  "multipleOfShouldNotBeZero": {
+    "multipleOf": 0
   }
 }