Date-time validation fails depending on local time zone (#363)

* Add test for date-time validation on daylight savings time

* Fix locale-dependent validation of date-time

Author: ennoruijters

src/main/java/com/networknt/schema/DateTimeValidator.java

@@ -25,6 +25,7 @@
 import java.util.Collections;
 import java.util.LinkedHashSet;
 import java.util.Set;
+import java.util.TimeZone;
 import java.util.regex.Matcher;
 import java.util.regex.Pattern;
 
@@ -136,6 +137,7 @@ private boolean isLegalDateTime(String string) {
     private boolean validateDateTime(String dateTime, String pattern) {
         SimpleDateFormat sdf = new SimpleDateFormat(pattern);
         sdf.setLenient(false);
+        sdf.setTimeZone(TimeZone.getTimeZone("UTC"));
         return sdf.parse(dateTime, new ParsePosition(0)) != null;
     }
 }

src/test/java/com/networknt/schema/DateTimeDSTTest.java

@@ -0,0 +1,34 @@
+package com.networknt.schema;
+
+import com.fasterxml.jackson.databind.JsonNode;
+import com.fasterxml.jackson.databind.ObjectMapper;
+import org.junit.Assert;
+import org.junit.Test;
+
+import java.io.InputStream;
+import java.util.Set;
+
+public class DateTimeDSTTest {
+    protected JsonSchema getJsonSchemaFromStreamContentV7(InputStream schemaContent) {
+        JsonSchemaFactory factory = JsonSchemaFactory.getInstance(SpecVersion.VersionFlag.V7);
+        return factory.getSchema(schemaContent);
+    }
+
+    protected JsonNode getJsonNodeFromStreamContent(InputStream content) throws Exception {
+        ObjectMapper mapper = new ObjectMapper();
+        JsonNode node = mapper.readTree(content);
+        return node;
+    }
+
+    @Test
+    public void shouldWorkV7() throws Exception {
+        String schemaPath = "/schema/dateTimeArray.json";
+        String dataPath = "/data/dstTimes.json"; // Contains 2020 DST changes for various countries
+        InputStream schemaInputStream = getClass().getResourceAsStream(schemaPath);
+        JsonSchema schema = getJsonSchemaFromStreamContentV7(schemaInputStream);
+        InputStream dataInputStream = getClass().getResourceAsStream(dataPath);
+        JsonNode node = getJsonNodeFromStreamContent(dataInputStream);
+        Set<ValidationMessage> errors = schema.validate(node);
+        Assert.assertEquals(0, errors.size());
+    }
+}

src/test/resources/data/dstTimes.json

@@ -0,0 +1,8 @@
+[
+	"2020-03-29T02:00:00Z",
+	"2020-09-27T02:00:00Z",
+	"2020-03-15T02:00:00Z",
+	"2020-03-08T02:00:00Z",
+	"2020-03-27T02:00:00Z",
+	"2020-08-04T02:00:00Z"
+]

src/test/resources/schema/dateTimeArray.json

@@ -0,0 +1,10 @@
+{
+  "$id": "https://example.com/dateTimeTest.schema.json",
+  "$schema": "http://json-schema.org/draft-07/schema#",
+  "type": "array",
+  "items": {
+    "type": "string",
+    "format": "date-time"
+  }
+}
+