Properly map java.time.Instant to TIMESTAMPTZ

Java's `Instant` type is a fixed point in time (unix epoch which is
always UTC) and therefore similar to `OffsetDateTime`. Currently Instant
is mapped to a `TIMESTAMP` which is incorrect. This commit changes this
to `TIMESTAMPTZ` which is Postgres' type for specific points in time and
is the same way the official driver handles this.

Author: bzikarsky

src/main/java/io/r2dbc/postgresql/codec/InstantCodec.java

@@ -25,14 +25,10 @@
 import io.r2dbc.postgresql.util.ByteBufUtils;
 import reactor.util.annotation.Nullable;
 
-import java.time.Instant;
-import java.time.LocalDate;
-import java.time.LocalDateTime;
-import java.time.ZoneId;
-import java.time.ZoneOffset;
+import java.time.*;
 
 import static io.r2dbc.postgresql.message.Format.FORMAT_TEXT;
-import static io.r2dbc.postgresql.type.PostgresqlObjectId.TIMESTAMP;
+import static io.r2dbc.postgresql.type.PostgresqlObjectId.TIMESTAMPTZ;
 
 final class InstantCodec extends AbstractTemporalCodec<Instant> {
 
@@ -45,7 +41,7 @@ final class InstantCodec extends AbstractTemporalCodec<Instant> {
 
     @Override
     public Parameter encodeNull() {
-        return createNull(TIMESTAMP, FORMAT_TEXT);
+        return createNull(TIMESTAMPTZ, FORMAT_TEXT);
     }
 
     @Override
@@ -70,7 +66,7 @@ Instant doDecode(ByteBuf buffer, PostgresqlObjectId dataType, @Nullable Format f
     Parameter doEncode(Instant value) {
         Assert.requireNonNull(value, "value must not be null");
 
-        return create(TIMESTAMP, FORMAT_TEXT, () -> ByteBufUtils.encode(this.byteBufAllocator, value.toString()));
+        return create(TIMESTAMPTZ, FORMAT_TEXT, () -> ByteBufUtils.encode(this.byteBufAllocator, value.toString()));
     }
 
     @Override

src/test/java/io/r2dbc/postgresql/AbstractCodecIntegrationTests.java

@@ -180,7 +180,7 @@ void inetAddress() throws UnknownHostException {
 
     @Test
     void instant() {
-        testCodec(Instant.class, Instant.now(), "TIMESTAMP");
+        testCodec(Instant.class, Instant.now(), "TIMESTAMPTZ");
     }
 
     @Test

src/test/java/io/r2dbc/postgresql/codec/InstantCodecTest.java

@@ -75,6 +75,8 @@ void doCanDecode() {
         assertThat(codec.doCanDecode(TIMESTAMP, FORMAT_BINARY)).isTrue();
         assertThat(codec.doCanDecode(MONEY, FORMAT_TEXT)).isFalse();
         assertThat(codec.doCanDecode(TIMESTAMP, FORMAT_TEXT)).isTrue();
+        assertThat(codec.doCanDecode(TIMESTAMPTZ, FORMAT_TEXT)).isTrue();
+        assertThat(codec.doCanDecode(TIMESTAMPTZ, FORMAT_BINARY)).isTrue();
     }
 
     @Test
@@ -95,7 +97,7 @@ void doEncode() {
 
         assertThat(new InstantCodec(TEST).doEncode(instant))
             .hasFormat(FORMAT_TEXT)
-            .hasType(TIMESTAMP.getObjectId())
+            .hasType(TIMESTAMPTZ.getObjectId())
             .hasValue(encode(TEST, instant.toString()));
     }
 
@@ -108,7 +110,7 @@ void doEncodeNoValue() {
     @Test
     void encodeNull() {
         assertThat(new InstantCodec(TEST).encodeNull())
-            .isEqualTo(new Parameter(FORMAT_TEXT, TIMESTAMP.getObjectId(), NULL_VALUE));
+            .isEqualTo(new Parameter(FORMAT_TEXT, TIMESTAMPTZ.getObjectId(), NULL_VALUE));
     }
 
 }