Prepend jdbc: to DatabaseMetaData.getURL result

Fixed the PrestoDatabaseMetaData implementation of the getURL method to
include the jdbc: prefix in the resulting URL. A JDBC URL always starts with jdbc:.

Added an unit and a product test to verify that the database connection URL starts with the expected jdbc: prefix.

presto-jdbc/src/main/java/com/facebook/presto/jdbc/PrestoDatabaseMetaData.java

@@ -33,6 +33,7 @@
 public class PrestoDatabaseMetaData
         implements DatabaseMetaData
 {
+    private static final String JDBC_URL_START = "jdbc:";
     private static final String SEARCH_STRING_ESCAPE = "\\";
 
     private final PrestoConnection connection;
@@ -60,7 +61,7 @@ public boolean allTablesAreSelectable()
     public String getURL()
             throws SQLException
     {
-        return connection.getURI().toString();
+        return JDBC_URL_START + connection.getURI().toString();
     }
 
     @Override

presto-jdbc/src/test/java/com/facebook/presto/jdbc/TestPrestoDatabaseMetaData.java

@@ -174,6 +174,14 @@ public void testGetClientInfoProperties()
         }
     }
 
+    @Test
+    public void testGetUrl()
+            throws Exception
+    {
+        DatabaseMetaData metaData = connection.getMetaData();
+        assertEquals(metaData.getURL(), "jdbc:presto://" + server.getAddress());
+    }
+
     private static void assertColumnSpec(ResultSet rs, int dataType, Long precision, Long numPrecRadix, String typeName)
             throws SQLException
     {

presto-product-tests/src/main/java/com/facebook/presto/tests/jdbc/JdbcTests.java

@@ -304,6 +304,17 @@ public void testDeallocate()
         }
     }
 
+    @Test(groups = JDBC)
+    @Requires(ImmutableNationTable.class)
+    public void testMetaDataGetURL()
+            throws SQLException
+    {
+        DatabaseMetaData metaData = metaData();
+        String url = metaData.getURL();
+        assertThat(url).startsWith("jdbc:presto://");
+        assertThat(url).isEqualTo(prestoJdbcURL);
+    }
+
     private QueryResult queryResult(Statement statement, String query)
             throws SQLException
     {