Fix NPE with Statement.closeOnCompletion()

src/main/java/com/microsoft/sqlserver/jdbc/SQLServerPreparedStatement.java

@@ -657,7 +657,7 @@ private boolean retryBasedOnFailedReuseOfCachedHandle(SQLException e, int attemp
     boolean consumeExecOutParam(TDSReader tdsReader) throws SQLServerException {
         final class PrepStmtExecOutParamHandler extends StmtExecOutParamHandler {
 
-            PrepStmtExecOutParamHandler(SQLServerStatement statement) {            
+            PrepStmtExecOutParamHandler(SQLServerStatement statement) {
                 super(statement);
             }
 
@@ -954,7 +954,7 @@ private void getParameterEncryptionMetadata(Parameter[] params) throws SQLServer
                                             DescribeParameterEncryptionResultSet2.ColumnEncryptionAlgorithm.value()),
                                     null, encType.value, (byte) secondRs.getInt(
                                             DescribeParameterEncryptionResultSet2.NormalizationRuleVersion.value()));
-                            
+
                             SQLServerStatement statement = (SQLServerStatement) stmt;
                             // Decrypt the symmetric key.(This will also validate and throw if needed).
                             SQLServerSecurityUtility.decryptSymmetricKey(params[paramIndex].cryptoMeta, connection, statement);

src/main/java/com/microsoft/sqlserver/jdbc/SQLServerStatement.java

@@ -409,7 +409,7 @@ final boolean isCursorable(int executeMethod) {
 
     class StmtExecOutParamHandler extends TDSTokenHandler {
         SQLServerStatement statement;
-        StmtExecOutParamHandler(SQLServerStatement statement) {            
+        StmtExecOutParamHandler(SQLServerStatement statement) {
             super("StmtExecOutParamHandler");
             this.statement = statement;
         }
@@ -1320,6 +1320,7 @@ final void ensureExecuteResultsReader(TDSReader tdsReader) {
     final void processExecuteResults() throws SQLServerException {
         if (wasExecuted()) {
             processBatch();
+            checkClosed(); // processBatch could have resulted in a closed connection if isCloseOnCompletion is set
             TDSParser.parse(resultsReader(), "batch completion");
             ensureExecuteResultsReader(null);
         }

src/main/java/com/microsoft/sqlserver/jdbc/SQLServerSymmetricKeyCache.java

@@ -88,7 +88,7 @@ SQLServerSymmetricKey getKey(EncryptionKeyInfo keyInfo, SQLServerConnection conn
 
                 // search system/global key store providers
                 SQLServerColumnEncryptionKeyStoreProvider provider = connection.getSystemOrGlobalColumnEncryptionKeyStoreProvider(keyInfo.keyStoreName);
-                assert null != provider : "Provider should not be null.";                
+                assert null != provider : "Provider should not be null.";
 
                 byte[] plaintextKey;
 

src/test/java/com/microsoft/sqlserver/jdbc/TestUtils.java

@@ -477,7 +477,6 @@ public static String bytesToHexString(byte[] b, int length) {
         return sb.toString();
     }
 
-
     /**
      * 
      * @param b

src/test/java/com/microsoft/sqlserver/jdbc/unit/statement/StatementTest.java

@@ -7,6 +7,7 @@
 import static org.junit.Assert.assertArrayEquals;
 import static org.junit.Assert.fail;
 import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertNotNull;
 import static org.junit.jupiter.api.Assertions.assertTrue;
 
 import java.io.StringReader;
@@ -2052,6 +2053,41 @@ public void testClosedResultSet() throws Exception {
             }
         }
 
+        /**
+         * Tests reusing Statement after being automatically closed via closeOnCompletion().
+         *
+         * @throws Exception
+         */
+        @Test
+        public void testReuseAfterCloseOnCompletion() throws Exception {
+            try (Connection conn = getConnection(); Statement stmt = conn.createStatement()) {
+
+                // enable isCloseOnCompletion
+                try {
+                    stmt.closeOnCompletion();
+                } catch (Exception e) {
+                    fail(TestResource.getResource("R_unexpectedException") + e.getMessage());
+                }
+
+                try (SQLServerResultSet rs = (SQLServerResultSet) stmt.executeQuery("SELECT 1")) {
+                    assertNotNull(rs, TestResource.getResource("R_resultsetNull"));
+
+                    try {
+                        // Executing a new command should close the previous ResultSet
+                        // ... and closing the original ResultSet should close the Statement
+                        // ... so this should fail with an error indicating that the Statement is closed.
+                        stmt.executeQuery("SELECT 1");
+                        fail(TestResource.getResource("R_expectedExceptionNotThrown"));
+                    } catch (SQLException e) {
+                        assertEquals(TestResource.getResource("R_statementClosed"), e.getMessage());
+                    } catch (Exception e) {
+                        e.printStackTrace();
+                        fail(TestResource.getResource("R_unexpectedException") + e.getMessage());
+                    }
+                }
+            }
+        }
+
         /**
          * Tests closing statement will close resultset
          *