Support isWrapperFor() and unwrap() methods

Add missed implementation of Wrapper interface for SQLDatabaseMetadata,
SQLResultSet, and SQL ResultSetMetaData classes.

Closes: #73

Author: nicktorwald

src/main/java/org/tarantool/jdbc/SQLDatabaseMetadata.java

@@ -8,7 +8,7 @@
 import java.sql.ResultSet;
 import java.sql.RowIdLifetime;
 import java.sql.SQLException;
-import java.sql.SQLFeatureNotSupportedException;
+import java.sql.SQLNonTransientException;
 import java.sql.Types;
 import java.util.ArrayList;
 import java.util.Arrays;
@@ -1117,13 +1117,16 @@ public boolean generatedKeyAlwaysReturned() throws SQLException {
     }
 
     @Override
-    public <T> T unwrap(Class<T> iface) throws SQLException {
-        throw new SQLFeatureNotSupportedException();
+    public <T> T unwrap(Class<T> type) throws SQLException {
+        if (isWrapperFor(type)) {
+            return type.cast(this);
+        }
+        throw new SQLNonTransientException("SQLDatabaseMetadata does not wrap " + type.getName());
     }
 
     @Override
-    public boolean isWrapperFor(Class<?> iface) throws SQLException {
-        throw new SQLFeatureNotSupportedException();
+    public boolean isWrapperFor(Class<?> type) throws SQLException {
+        return type.isAssignableFrom(this.getClass());
     }
 
     private ResultSet asMetadataResultSet(JDBCBridge jdbcBridge) throws SQLException {

src/main/java/org/tarantool/jdbc/SQLResultSet.java

@@ -1081,13 +1081,16 @@ public void updateNCharacterStream(String columnLabel, Reader reader) throws SQL
     }
 
     @Override
-    public <T> T unwrap(Class<T> iface) throws SQLException {
-        throw new SQLFeatureNotSupportedException();
+    public <T> T unwrap(Class<T> type) throws SQLException {
+        if (isWrapperFor(type)) {
+            return type.cast(this);
+        }
+        throw new SQLNonTransientException("ResultSet does not wrap " + type.getName());
     }
 
     @Override
-    public boolean isWrapperFor(Class<?> iface) throws SQLException {
-        throw new SQLFeatureNotSupportedException();
+    public boolean isWrapperFor(Class<?> type) throws SQLException {
+        return type.isAssignableFrom(this.getClass());
     }
 
     @Override

src/main/java/org/tarantool/jdbc/SQLResultSetMetaData.java

@@ -5,6 +5,7 @@
 import java.sql.ResultSetMetaData;
 import java.sql.SQLException;
 import java.sql.SQLFeatureNotSupportedException;
+import java.sql.SQLNonTransientException;
 import java.sql.Types;
 
 public class SQLResultSetMetaData implements ResultSetMetaData {
@@ -120,13 +121,16 @@ public String getColumnClassName(int column) throws SQLException {
     }
 
     @Override
-    public <T> T unwrap(Class<T> iface) throws SQLException {
-        throw new SQLFeatureNotSupportedException();
+    public <T> T unwrap(Class<T> type) throws SQLException {
+        if (isWrapperFor(type)) {
+            return type.cast(this);
+        }
+        throw new SQLNonTransientException("ResultSetMetadata does not wrap " + type.getName());
     }
 
     @Override
-    public boolean isWrapperFor(Class<?> iface) throws SQLException {
-        throw new SQLFeatureNotSupportedException();
+    public boolean isWrapperFor(Class<?> type) throws SQLException {
+        return type.isAssignableFrom(this.getClass());
     }
 
     @Override

src/test/java/org/tarantool/jdbc/JdbcDatabaseMetaDataIT.java

@@ -255,4 +255,16 @@ public void testSupportsResultSetHoldability() throws SQLException {
         assertFalse(meta.supportsResultSetHoldability(42));
     }
 
+    @Test
+    public void testUnwrap() throws SQLException {
+        assertEquals(meta, meta.unwrap(SQLDatabaseMetadata.class));
+        assertThrows(SQLException.class, () -> meta.unwrap(Integer.class));
+    }
+
+    @Test
+    public void testIsWrapperFor() throws SQLException {
+        assertTrue(meta.isWrapperFor(SQLDatabaseMetadata.class));
+        assertFalse(meta.isWrapperFor(Integer.class));
+    }
+
 }

src/test/java/org/tarantool/jdbc/JdbcPreparedStatementIT.java

@@ -169,6 +169,22 @@ public void execute() throws Throwable {
         assertEquals(3, i);
     }
 
+    @Test
+    public void testUnwrap() throws SQLException {
+        prep = conn.prepareStatement("SELECT val FROM test");
+        assertEquals(prep, prep.unwrap(SQLPreparedStatement.class));
+        assertEquals(prep, prep.unwrap(SQLStatement.class));
+        assertThrows(SQLException.class, () -> prep.unwrap(Integer.class));
+    }
+
+    @Test
+    public void testIsWrapperFor() throws SQLException {
+        prep = conn.prepareStatement("SELECT val FROM test");
+        assertTrue(prep.isWrapperFor(SQLPreparedStatement.class));
+        assertTrue(prep.isWrapperFor(SQLStatement.class));
+        assertFalse(prep.isWrapperFor(Integer.class));
+    }
+
     @Test
     public void testSetByte() throws SQLException {
         makeHelper(Byte.class)

src/test/java/org/tarantool/jdbc/JdbcResultSetIT.java

@@ -3,6 +3,7 @@
 import static org.junit.jupiter.api.Assertions.assertEquals;
 import static org.junit.jupiter.api.Assertions.assertFalse;
 import static org.junit.jupiter.api.Assertions.assertNotNull;
+import static org.junit.jupiter.api.Assertions.assertThrows;
 import static org.junit.jupiter.api.Assertions.assertTrue;
 
 import org.junit.jupiter.api.AfterEach;
@@ -133,4 +134,18 @@ public void testHoldability() throws SQLException {
         assertEquals(metaData.getResultSetHoldability(), resultSet.getHoldability());
     }
 
+    @Test
+    public void testUnwrap() throws SQLException {
+        ResultSet resultSet = stmt.executeQuery("SELECT * FROM test WHERE id < 0");
+        assertEquals(resultSet, resultSet.unwrap(SQLResultSet.class));
+        assertThrows(SQLException.class, () -> resultSet.unwrap(Integer.class));
+    }
+
+    @Test
+    public void testIsWrapperFor() throws SQLException {
+        ResultSet resultSet = stmt.executeQuery("SELECT * FROM test WHERE id < 0");
+        assertTrue(resultSet.isWrapperFor(SQLResultSet.class));
+        assertFalse(resultSet.isWrapperFor(Integer.class));
+    }
+
 }

src/test/java/org/tarantool/jdbc/JdbcResultSetMetaDataIT.java

@@ -1,7 +1,10 @@
 package org.tarantool.jdbc;
 
 import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertFalse;
 import static org.junit.jupiter.api.Assertions.assertNotNull;
+import static org.junit.jupiter.api.Assertions.assertThrows;
+import static org.junit.jupiter.api.Assertions.assertTrue;
 
 import org.junit.jupiter.api.Test;
 
@@ -31,4 +34,28 @@ public void testColumnNames() throws SQLException {
         rs.close();
         stmt.close();
     }
+
+    @Test
+    public void testUnwrap() throws SQLException {
+        try (
+                Statement statement = conn.createStatement();
+                ResultSet resultSet = statement.executeQuery("SELECT * FROM test")
+        ) {
+            ResultSetMetaData metaData = resultSet.getMetaData();
+            assertEquals(metaData, metaData.unwrap(SQLResultSetMetaData.class));
+            assertThrows(SQLException.class, () -> metaData.unwrap(Integer.class));
+        }
+    }
+
+    @Test
+    public void testIsWrapperFor() throws SQLException {
+        try (
+                Statement statement = conn.createStatement();
+                ResultSet resultSet = statement.executeQuery("SELECT * FROM test")
+        ) {
+            ResultSetMetaData metaData = resultSet.getMetaData();
+            assertTrue(metaData.isWrapperFor(SQLResultSetMetaData.class));
+            assertFalse(metaData.isWrapperFor(Integer.class));
+        }
+    }
 }

src/test/java/org/tarantool/jdbc/JdbcStatementIT.java

@@ -94,4 +94,17 @@ public void execute() throws Throwable {
         }
         assertEquals(3, i);
     }
+
+    @Test
+    public void testUnwrap() throws SQLException {
+        assertEquals(stmt, stmt.unwrap(SQLStatement.class));
+        assertThrows(SQLException.class, () -> stmt.unwrap(Integer.class));
+    }
+
+    @Test
+    public void testIsWrapperFor() throws SQLException {
+        assertTrue(stmt.isWrapperFor(SQLStatement.class));
+        assertFalse(stmt.isWrapperFor(Integer.class));
+    }
+
 }