Fix parsing timestamps with zone 'Z'

api/src/main/java/dev/paseto/jpaseto/lang/DateFormats.java

@@ -31,7 +31,7 @@ private DateFormats() {}
     public static final DateTimeFormatter ISO_OFFSET_DATE_TIME = new DateTimeFormatterBuilder()
                 .parseCaseInsensitive()
                 .append(DateTimeFormatter.ISO_LOCAL_DATE_TIME)
-                .appendOffset("+HH:MM", "+00:00")
+                .appendOffsetId() // append UTC designator "Z"
                 .toFormatter()
                 .withZone(ZoneOffset.UTC);
 
@@ -43,4 +43,4 @@ public static Instant parseIso8601Date(String s) throws DateTimeException {
         Assert.notNull(s, "String argument cannot be null.");
         return Instant.from(ISO_OFFSET_DATE_TIME.parse(s));
     }
-}
+}

extensions/json/jackson/src/test/groovy/dev/paseto/jpaseto/io/jackson/JacksonSerializerTest.groovy

@@ -96,7 +96,7 @@ class JacksonSerializerTest {
     @Test
     void testDateTime() {
         DateTimeFormatter dateTimeFormatter = DateFormats.ISO_OFFSET_DATE_TIME
-        def anInstantString = "2019-01-01T00:00:00+00:00"
+        def anInstantString = "2019-01-01T00:00:00Z"
         def dateTime = Instant.from(dateTimeFormatter.parse(anInstantString))
 
         def expected = '{"hello":"' + anInstantString +  '"}'

impl/src/test/groovy/dev/paseto/jpaseto/impl/DateFormatsTest.groovy

@@ -0,0 +1,54 @@
+/*
+ * Copyright (C) 2015 jsonwebtoken.io
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package dev.paseto.jpaseto.impl
+
+import dev.paseto.jpaseto.RequiredTypeException
+import dev.paseto.jpaseto.lang.DateFormats
+import org.hamcrest.MatcherAssert
+import org.testng.annotations.Test
+
+import java.time.Instant
+import java.time.ZoneId
+import java.time.ZonedDateTime
+
+import static org.hamcrest.MatcherAssert.assertThat
+import static org.hamcrest.Matchers.*
+
+class DateFormatsTest {
+    @Test
+    void testParseIso8601String() {
+        def d = ZonedDateTime.of(2015, 1, 1, 12, 0, 0, 0, ZoneId.of("UTC")).toInstant()
+        String s = "2015-01-01T12:00:00+00:00"
+        Instant instant = DateFormats.parseIso8601Date(s)
+        assertThat instant, is(d)
+    }
+
+    @Test
+    void testParseIso8601ZString() {
+        def d = ZonedDateTime.of(2015, 1, 1, 12, 0, 0, 0, ZoneId.of("UTC")).toInstant()
+        String s = "2015-01-01T12:00:00Z"
+        Instant instant = DateFormats.parseIso8601Date(s)
+        assertThat instant, is(d)
+    }
+
+    @Test
+    void testFormatDateWithIso8601String() {
+        def d = ZonedDateTime.of(2015, 1, 1, 12, 0, 0, 0, ZoneId.of("UTC")).toInstant()
+        String exp = "2015-01-01T12:00:00Z"
+        String s = DateFormats.formatIso8601(d)
+        assertThat s, is(exp)
+    }
+}