Merge pull request #598 from commercetools/java-time-json-compat

Be more lenient in accepted instants

json/json-core/src/main/scala/io/sphere/json/FromJSON.scala

@@ -380,8 +380,32 @@ object FromJSON extends FromJSONInstances {
     }
 
   // java.time
+  // this formatter is used to parse instant in an extra lenient way
+  // similar to what the joda `DateTime` constructor accepts
+  // the accepted grammar for joda is described here: https://www.joda.org/joda-time/apidocs/org/joda/time/format/ISODateTimeFormat.html#dateTimeParser--
+  // this only supports the part where the date is specified
+  private val lenientInstantParser =
+    new time.format.DateTimeFormatterBuilder()
+      .appendPattern("uuuu[-MM[-dd]]")
+      .optionalStart()
+      .appendPattern("'T'[HH[:mm[:ss]]]")
+      .appendFraction(time.temporal.ChronoField.NANO_OF_SECOND, 0, 9, true)
+      .optionalStart()
+      .appendZoneOrOffsetId()
+      .optionalEnd()
+      .optionalEnd()
+      .parseDefaulting(time.temporal.ChronoField.MONTH_OF_YEAR, 1L)
+      .parseDefaulting(time.temporal.ChronoField.DAY_OF_MONTH, 1L)
+      .parseDefaulting(time.temporal.ChronoField.HOUR_OF_DAY, 0L)
+      .parseDefaulting(time.temporal.ChronoField.MINUTE_OF_HOUR, 0L)
+      .parseDefaulting(time.temporal.ChronoField.SECOND_OF_MINUTE, 0L)
+      .parseDefaulting(time.temporal.ChronoField.NANO_OF_SECOND, 0L)
+      .toFormatter()
+      .withZone(time.ZoneOffset.UTC)
+
   implicit val javaInstantReader: FromJSON[time.Instant] =
-    jsonStringReader("Failed to parse date/time: %s")(time.Instant.parse(_))
+    jsonStringReader("Failed to parse date/time: %s")(s =>
+      time.Instant.from(lenientInstantParser.parse(s)))
 
   implicit val javaLocalTimeReader: FromJSON[time.LocalTime] =
     jsonStringReader("Failed to parse time: %s")(

json/json-core/src/test/scala/io/sphere/json/DateTimeParsingSpec.scala

@@ -3,6 +3,8 @@ package io.sphere.json
 import org.json4s.JString
 import org.scalatest.matchers.should.Matchers
 import org.scalatest.wordspec.AnyWordSpec
+import java.time.Instant
+import cats.data.Validated.Valid
 
 class DateTimeParsingSpec extends AnyWordSpec with Matchers {
 
@@ -107,4 +109,65 @@ class DateTimeParsingSpec extends AnyWordSpec with Matchers {
       javaInstantReader.read(jsonDateStringWith(secondOfTheMinute = "87")) shouldNot beValid
     }
   }
+
+  // ported from https://github.com/JodaOrg/joda-time/blob/4a1402a47cab4636bf4c73d42a62bfa80c1535ca/src/test/java/org/joda/time/convert/TestStringConverter.java#L114-L156
+  // ensures that we accept similar patterns as joda when parsing instants
+  "parsing a Java instant" should {
+    "accept a full instant with milliseconds and offset" in {
+      javaInstantReader.read(JString("2004-06-09T12:24:48.501+08:00")) shouldBe Valid(
+        Instant.parse("2004-06-09T04:24:48.501Z"))
+    }
+
+    "accept a year with offset" in {
+      javaInstantReader.read(JString("2004T+08:00")) shouldBe Valid(
+        Instant.parse("2004-01-01T00:00:00+08:00"))
+    }
+
+    "accept a year month with offset" in {
+      javaInstantReader.read(JString("2004-06T+08:00")) shouldBe Valid(
+        Instant.parse("2004-06-01T00:00:00+08:00"))
+    }
+
+    "accept a year month day with offset" in {
+      javaInstantReader.read(JString("2004-06-09T+08:00")) shouldBe Valid(
+        Instant.parse("2004-06-09T00:00:00+08:00"))
+    }
+
+    "accept a year month day with hour and offset" in {
+      javaInstantReader.read(JString("2004-06-09T12+08:00")) shouldBe Valid(
+        Instant.parse("2004-06-09T04:00:00Z"))
+    }
+
+    "accept a year month day with hour, minute, and offset" in {
+      javaInstantReader.read(JString("2004-06-09T12:24+08:00")) shouldBe Valid(
+        Instant.parse("2004-06-09T04:24:00Z"))
+    }
+
+    "accept a year month day with hour, minute, second, and offset" in {
+      javaInstantReader.read(JString("2004-06-09T12:24:48+08:00")) shouldBe Valid(
+        Instant.parse("2004-06-09T04:24:48Z"))
+    }
+
+    "accept a year month day with hour, fraction, and offset" in {
+      javaInstantReader.read(JString("2004-06-09T12.5+08:00")) shouldBe Valid(
+        Instant.parse("2004-06-09T04:00:00.5Z"))
+    }
+
+    "accept a year month day with hour, minute, fraction, and offset" in {
+      javaInstantReader.read(JString("2004-06-09T12:24.5+08:00")) shouldBe Valid(
+        Instant.parse("2004-06-09T04:24:00.5Z"))
+    }
+
+    "accept a year month day with hour, minute, second, fraction, and offset" in {
+      javaInstantReader.read(JString("2004-06-09T12:24:48.5+08:00")) shouldBe Valid(
+        Instant.parse("2004-06-09T04:24:48.5Z"))
+    }
+
+    "accept a year month day with hour, minute, second, fraction, but no offset" in {
+      javaInstantReader.read(JString("2004-06-09T12:24:48.501")) shouldBe Valid(
+        Instant.parse("2004-06-09T12:24:48.501Z"))
+    }
+
+  }
+
 }