Fix getTransactionIsolationLevel for read-only and read-write

Author: Michael-A-McMahon

src/main/java/oracle/r2dbc/impl/OracleConnectionImpl.java

@@ -643,8 +643,16 @@ public Publisher<Void> setStatementTimeout(Duration timeout) {
    * <p>
    * Implements the R2DBC SPI method by returning the isolation level set for
    * the database session of this {@code Connection}, if the session is not
-   * currently in a transaction. If the session is in a transaction, then the
-   * isolation level of that transaction is returned.
+   * currently in a transaction.
+   * </p><p>
+   * If the session is in a transaction, and an isolation level was
+   * explicitly specified via {@link TransactionDefinition#ISOLATION_LEVEL},
+   * then the isolation level of that transaction is returned. If the current
+   * transaction is read-only, then {@link IsolationLevel#SERIALIZABLE} is
+   * returned as read-only transactions have the same behavior as if the
+   * SERIALIZABLE isolation level. Otherwise, if no isolation level was
+   * explicitly set, then the current transaction should have the isolation
+   * level set for the database session.
    * </p>
    * @throws IllegalStateException If this {@code Connection} is closed
    */
@@ -659,10 +667,11 @@ public IsolationLevel getTransactionIsolationLevel() {
       IsolationLevel currentIsolationLevel =
         currentTransaction.getAttribute(ISOLATION_LEVEL);
 
-      if (currentIsolationLevel == null)
-        return isolationLevel;
-      else
-        return currentIsolationLevel;
+      return currentIsolationLevel != null
+        ? currentIsolationLevel
+        : Boolean.TRUE == currentTransaction.getAttribute(READ_ONLY)
+          ? SERIALIZABLE
+          : isolationLevel;
     }
   }
 

src/test/java/oracle/r2dbc/impl/OracleConnectionImplTest.java

@@ -241,11 +241,14 @@ public void testBeginTransactionReadOnly() {
         awaitUpdate(1, sessionB.createStatement(
           "INSERT INTO testBeginTransactionReadOnly VALUES ('b')"));
 
-        // Begin a READ ONLY transaction with sessionA and expect a query result
-        // having only the committed row, and not the uncomitted row
+        // Begin a READ ONLY transaction with sessionA. Expect
+        // getTransactionIsolationLevel to return SERIALIZABLE as read-only
+        // transactions have the same behavior. Expect a query result
+        // having only the committed row, and not the uncommitted row
         awaitNone(sessionA.commitTransaction());
         awaitNone(sessionA.beginTransaction(transactionDefinition(Map.of(
           READ_ONLY, true))));
+        assertEquals(SERIALIZABLE, sessionA.getTransactionIsolationLevel());
         awaitQuery(List.of("a"), row -> row.get(0, String.class),
           sessionA.createStatement(
             "SELECT value FROM testBeginTransactionReadOnly"));
@@ -288,6 +291,12 @@ public void testBeginTransactionReadWrite() {
       verifyReadCommittedIsolation(connection, () ->
         connection.beginTransaction(transactionDefinition(Map.of(
           READ_ONLY, false))));
+
+      // Expect read write transactions to have the session's isolation level
+      awaitNone(connection.setTransactionIsolationLevel(SERIALIZABLE));
+      verifySerializableIsolation(connection, () ->
+        connection.beginTransaction(transactionDefinition(Map.of(
+          READ_ONLY, false))));
     }
     finally {
       tryAwaitNone(connection.close());
@@ -367,6 +376,7 @@ private static void verifyReadCommittedIsolation(
         sessionA.isAutoCommit(),
         "Unexpected return value from isAutoCommit() after" +
           " beginTransaction()");
+      assertEquals(READ_COMMITTED, sessionA.getTransactionIsolationLevel());
       awaitUpdate(1, sessionA.createStatement(
         "INSERT INTO verifyReadCommittedIsolation VALUES ('A')"));
 
@@ -455,6 +465,7 @@ private static void verifySerializableIsolation(
         sessionA.isAutoCommit(),
         "Unexpected return value from isAutoCommit() after" +
           " beginTransaction()");
+      assertEquals(SERIALIZABLE, sessionA.getTransactionIsolationLevel());
       awaitUpdate(1, sessionA.createStatement(
         "INSERT INTO verifySerializableIsolation VALUES ('A')"));
 
@@ -1018,7 +1029,25 @@ public void testGetTransactionIsolationLevel() {
         "Unexpected return value of getTransactionIsolationLevel() for a" +
           " newly created connection");
 
-      // TODO: Verify serializable
+
+      // Begin a transaction with a different level that what was passed to
+      // setTransactionIsolationLevel. Expect the getter to return the level
+      // of the current transaction
+      awaitNone(connection.beginTransaction(SERIALIZABLE));
+      assertEquals(SERIALIZABLE, connection.getTransactionIsolationLevel());
+
+      // End the transaction and expect the getter to return the setter value
+      awaitNone(connection.commitTransaction());
+      assertEquals(READ_COMMITTED, connection.getTransactionIsolationLevel());
+
+      // Set the level and expect the getter to return it
+      awaitNone(connection.setTransactionIsolationLevel(SERIALIZABLE));
+      assertEquals(SERIALIZABLE, connection.getTransactionIsolationLevel());
+
+      // Begin a READ ONLY transaction, expect the READ COMMITTED ISOLATION
+      // level.
+      //TODO
+
     }
     finally {
       tryAwaitNone(connection.close());