Add methods to KiwiJdbc to convert java.sql.Date to LocalDate

Add two localDateOrNullFromDate methods, one that accepts a
ResultSet and colum name, and one that accepts a java.sql.Date.
They are both annotated with the Checker Nullable annotation to
indicate null can be returned, and also that the java.sql.Date
argument can be null as well.

Closes #1044

src/main/java/org/kiwiproject/jdbc/KiwiJdbc.java

@@ -4,13 +4,15 @@
 import static org.kiwiproject.base.KiwiPreconditions.checkArgumentNotNull;
 
 import lombok.experimental.UtilityClass;
+import org.checkerframework.checker.nullness.qual.Nullable;
 
 import java.sql.PreparedStatement;
 import java.sql.ResultSet;
 import java.sql.SQLException;
 import java.sql.Timestamp;
 import java.sql.Types;
 import java.time.Instant;
+import java.time.LocalDate;
 import java.time.LocalDateTime;
 import java.time.ZoneId;
 import java.time.ZoneOffset;
@@ -118,6 +120,30 @@ public static LocalDateTime localDateTimeFromTimestamp(Timestamp timestamp) {
         return isNull(timestamp) ? null : timestamp.toLocalDateTime();
     }
 
+    /**
+     * Returns a {@link LocalDate} from the specified {@link java.sql.Date} column in the given {@link ResultSet}.
+     *
+     * @param rs         the ResultSet
+     * @param columnName the date column name
+     * @return the converted LocalDate or {@code null} if the column was {@code NULL}
+     * @throws SQLException if there is problem getting the date
+     */
+    @Nullable
+    public static LocalDate localDateOrNullFromDate(ResultSet rs, String columnName) throws SQLException {
+        return localDateOrNullFromDate(rs.getDate(columnName));
+    }
+
+    /**
+     * Returns a {@link LocalDateTime} from the given {@link java.sql.Date}.
+     *
+     * @param date the date to convert
+     * @return the converted LocalDate or {@code null} if the date is {@code null}
+     */
+    @Nullable
+    public static LocalDate localDateOrNullFromDate(java.sql.@Nullable Date date) {
+        return isNull(date) ? null : date.toLocalDate();
+    }
+
     /**
      * Returns a {@link ZonedDateTime} in UTC from the specified column in the {@link ResultSet}.
      *

src/test/java/org/kiwiproject/jdbc/KiwiJdbcTest.java

@@ -2,6 +2,7 @@
 
 import static org.assertj.core.api.Assertions.assertThat;
 import static org.assertj.core.api.Assertions.assertThatIllegalArgumentException;
+import static org.mockito.ArgumentMatchers.anyString;
 import static org.mockito.Mockito.mock;
 import static org.mockito.Mockito.verify;
 import static org.mockito.Mockito.verifyNoMoreInteractions;
@@ -19,7 +20,9 @@
 import java.sql.Timestamp;
 import java.sql.Types;
 import java.time.Instant;
+import java.time.LocalDate;
 import java.time.LocalDateTime;
+import java.time.Month;
 import java.time.ZoneId;
 import java.time.ZoneOffset;
 import java.time.ZonedDateTime;
@@ -194,6 +197,49 @@ void shouldReturnNull_WhenResultSet_ReturnsNullTimestamp() throws SQLException {
         }
     }
 
+    @Nested
+    class LocalDateFromJavaSqlDate {
+
+        @Test
+        void shouldConvertFromDate() {
+            var originalDate = LocalDate.of(2023, Month.APRIL, 1);
+            var date = java.sql.Date.valueOf(originalDate);
+
+            assertThat(KiwiJdbc.localDateOrNullFromDate(date)).isEqualTo(originalDate);
+        }
+
+        @Test
+        void shouldReturnNull_WhenGivenNullDate() {
+            assertThat(KiwiJdbc.localDateOrNullFromDate(null)).isNull();
+        }
+
+        @Test
+        void shouldConvertFromResultSet() throws SQLException {
+            var originalDate = LocalDate.of(2023, Month.SEPTEMBER, 8);
+            var date = java.sql.Date.valueOf(originalDate);
+
+            var resultSet = newMockResultSet();
+            when(resultSet.getDate(anyString())).thenReturn(date);
+
+            assertThat(KiwiJdbc.localDateOrNullFromDate(resultSet, "date_of_birth"))
+                    .isEqualTo(originalDate);
+
+            verify(resultSet).getDate("date_of_birth");
+            verifyNoMoreInteractions(resultSet);
+        }
+
+        @Test
+        void shouldReturnNull_WhenResultSet_ReturnsNullDate() throws SQLException {
+            var resultSet = newMockResultSet();
+            when(resultSet.getDate(anyString())).thenReturn(null);
+
+            assertThat(KiwiJdbc.localDateOrNullFromDate(resultSet, "expiration_date")).isNull();
+
+            verify(resultSet).getDate("expiration_date");
+            verifyNoMoreInteractions(resultSet);
+        }
+    }
+
     @Nested
     class UtcZonedDateTimeFromTimestamp {
 
@@ -638,4 +684,4 @@ private static ResultSet newMockResultSet() {
     private PreparedStatement newMockPreparedStatement() {
         return mock(PreparedStatement.class);
     }
-}
+}