Add fix for null-valued TIMESTAMP (#188)

pom.xml

@@ -230,6 +230,7 @@
               <version>1.7</version>
               <style>GOOGLE</style>
             </googleJavaFormat>
+            <toggleOffOn />
           </java>
         </configuration>
       </plugin>

src/main/java/net/starschema/clouddb/jdbc/DateTimeUtils.java

@@ -99,6 +99,9 @@ static Timestamp parseDateTime(String value, Calendar cal) throws SQLException {
 
   /** Parse a BigQuery TIMESTAMP literal, represented as the number of seconds since epoch. */
   static Timestamp parseTimestamp(String value) throws SQLException {
+    if (value == null) {
+      return null;
+    }
     try {
       // BigQuery TIMESTAMP has a string representation that looks like e.g. "1.288061375E9"
       // for 2010-10-26 02:49:35 UTC.
@@ -119,6 +122,9 @@ static Timestamp parseTimestamp(String value) throws SQLException {
   }
 
   static String formatTimestamp(String rawString) throws SQLException {
+    if (rawString == null) {
+      return null;
+    }
     Timestamp timestamp = parseTimestamp(rawString);
     return DATETIME_FORMATTER.format(OffsetDateTime.ofInstant(timestamp.toInstant(), UTC_ZONE))
         + " UTC";

src/test/java/net/starschema/clouddb/jdbc/BQForwardOnlyResultSetFunctionTest.java

@@ -38,6 +38,7 @@
 import java.text.DateFormat;
 import java.text.ParseException;
 import java.text.SimpleDateFormat;
+import java.time.Instant;
 import java.util.Calendar;
 import java.util.Date;
 import java.util.GregorianCalendar;
@@ -796,6 +797,62 @@ public void testHandlesAllNullResponseFields() throws Exception {
     throw new AssertionError("Expected graceful failure due to lack of job reference");
   }
 
+  @Test
+  public void testHandlesNullTimeDateObjects() throws Exception {
+    this.NewConnection("&useLegacySql=false");
+    Statement stmt =
+        BQForwardOnlyResultSetFunctionTest.con.createStatement(
+            ResultSet.TYPE_FORWARD_ONLY, ResultSet.CONCUR_READ_ONLY);
+
+    final String date = "2011-11-11";
+    final String time = "12:12:12";
+    final String dateTime = date + " " + time;
+    final String dateTimeWithT = date + "T" + time;
+    // The number of milliseconds between epoch and 2011-11-11 12:12:12 UTC+0.
+    final long millis = 1321013532000L;
+
+    // spotless:off
+    String sql = "SELECT " +
+        "TIMESTAMP('" + dateTime + "') AS ts, " +
+        "DATETIME('" + dateTime + "') AS dt, " +
+        "DATE('" + date + "') AS d, " +
+        "TIME(12, 12, 12) AS t\n" +
+        "UNION ALL SELECT " +
+        "CASE WHEN 1 = 0 THEN TIMESTAMP('" + dateTime + "') ELSE NULL END, " +
+        "CASE WHEN 1 = 0 THEN DATETIME('" + dateTime + "') ELSE NULL END, " +
+        "CASE WHEN 1 = 0 THEN DATE('" + date + "') ELSE NULL END, " +
+        "CASE WHEN 1 = 0 THEN TIME(12, 12, 12) ELSE NULL END";
+    // spotless:on
+
+    ResultSet results = stmt.executeQuery(sql);
+
+    // First row has all non-null objects.
+    Assertions.assertThat(results.next()).isTrue();
+    Assertions.assertThat(results.getObject("ts"))
+        .isEqualTo(Timestamp.from(Instant.ofEpochMilli(millis)));
+    Assertions.assertThat(results.getString("ts")).isEqualTo(dateTime + " UTC");
+    Assertions.assertThat(results.getObject("dt")).isEqualTo(Timestamp.valueOf(dateTime));
+    Assertions.assertThat(results.getString("dt")).isEqualTo(dateTimeWithT);
+    Assertions.assertThat(results.getObject("d")).isEqualTo(java.sql.Date.valueOf(date));
+    Assertions.assertThat(results.getString("d")).isEqualTo(date);
+    Assertions.assertThat(results.getObject("t")).isEqualTo(java.sql.Time.valueOf(time));
+    Assertions.assertThat(results.getString("t")).isEqualTo(time);
+
+    // Second row is all null.
+    Assertions.assertThat(results.next()).isTrue();
+    Assertions.assertThat(results.getObject("ts")).isNull();
+    Assertions.assertThat(results.getString("ts")).isNull();
+    Assertions.assertThat(results.getObject("dt")).isNull();
+    Assertions.assertThat(results.getString("dt")).isNull();
+    Assertions.assertThat(results.getObject("d")).isNull();
+    Assertions.assertThat(results.getString("d")).isNull();
+    Assertions.assertThat(results.getObject("t")).isNull();
+    Assertions.assertThat(results.getString("t")).isNull();
+
+    // Only two rows.
+    Assertions.assertThat(results.next()).isFalse();
+  }
+
   @Test
   public void testHandlesSomeNullResponseFields() throws Exception {
     // Make sure we don't get any NPE's due to null values;