Improve Misleading Error Message in ContentTooLongException

rest5-client/src/main/java/co/elastic/clients/transport/rest5_client/low_level/BufferedByteConsumer.java

@@ -65,9 +65,10 @@ protected int capacityIncrement() {
 
     @Override
     protected void data(final ByteBuffer src, final boolean endOfStream) throws ContentTooLongException {
-        if (buffer.length() + src.limit() > limit) {
+        long contentLength = buffer.length() + src.limit();
+        if (contentLength > limit) {
             throw new ContentTooLongException(
-                "entity content is too long [" + src.limit() + "] for the configured buffer limit [" + limit + "]"
+                "entity content is too long [" + contentLength + "] for the configured buffer limit [" + limit + "]"
             );
         }
         buffer.append(src);

rest5-client/src/test/java/co/elastic/clients/transport/rest5_client/low_level/BufferedByteConsumerTest.java

@@ -0,0 +1,217 @@
+/*
+ * Licensed to Elasticsearch B.V. under one or more contributor
+ * license agreements. See the NOTICE file distributed with
+ * this work for additional information regarding copyright
+ * ownership. Elasticsearch B.V. licenses this file to you under
+ * the Apache License, Version 2.0 (the "License"); you may
+ * not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+
+package co.elastic.clients.transport.rest5_client.low_level;
+
+import org.apache.hc.core5.concurrent.FutureCallback;
+import org.apache.hc.core5.http.ContentTooLongException;
+import org.apache.hc.core5.http.io.entity.ByteArrayEntity;
+import org.junit.jupiter.api.Test;
+
+import java.nio.ByteBuffer;
+import java.nio.charset.StandardCharsets;
+
+import static org.junit.jupiter.api.Assertions.assertThrows;
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertTrue;
+import static org.junit.jupiter.api.Assertions.assertFalse;
+import static org.junit.jupiter.api.Assertions.fail;
+import static org.junit.jupiter.api.Assertions.assertDoesNotThrow;
+import static org.junit.jupiter.api.Assertions.assertNotNull;
+
+class BufferedByteConsumerTest extends RestClientTestCase {
+
+     @Test
+     void testConstructor() {
+         assertThrows(IllegalArgumentException.class, () -> new BufferedByteConsumer(0));
+         assertThrows(IllegalArgumentException.class, () -> new BufferedByteConsumer(-1));
+     }
+
+     @Test
+     void testCapacityIncrement() {
+         int bufferLimit = 1024;
+         BufferedByteConsumer consumer = new BufferedByteConsumer(bufferLimit);
+         assertEquals(bufferLimit, consumer.capacityIncrement());
+     }
+
+     @Test
+     void testContentTooLongException() {
+         int bufferLimit = 10;
+         BufferedByteConsumer consumer = new BufferedByteConsumer(bufferLimit);
+
+         // Start the stream
+         consumer.streamStart(null, null);
+
+         // Try to add data that exceeds the limit
+         byte[] data = "This is a long string that exceeds the buffer limit".getBytes(StandardCharsets.UTF_8);
+         ByteBuffer buffer = ByteBuffer.wrap(data);
+
+         ContentTooLongException exception = assertThrows(ContentTooLongException.class, () -> {
+             consumer.data(buffer, false);
+         });
+         assertEquals("entity content is too long [51] for the configured buffer limit [10]", exception.getMessage());
+     }
+
+    @Test
+    void testContentTooLongExceptionWithTwoCalls() {
+        int bufferLimit = 100;
+        BufferedByteConsumer consumer = new BufferedByteConsumer(bufferLimit);
+
+        // Start the stream
+        consumer.streamStart(null, null);
+
+        // Try to add data that exceeds the limit
+        byte[] data = "This is a long string that exceeds the buffer limit".getBytes(StandardCharsets.UTF_8);
+        ByteBuffer buffer = ByteBuffer.wrap(data);
+
+        ContentTooLongException exception = assertThrows(ContentTooLongException.class, () -> {
+            consumer.data(buffer, false);
+            consumer.data(buffer, false); // This should trigger the exception on the second call
+        });
+        assertEquals("entity content is too long [102] for the configured buffer limit [100]", exception.getMessage());
+    }
+
+     @Test
+     void testContentTooLongExceptionWithCallback() throws Exception {
+         int bufferLimit = 10;
+         BufferedByteConsumer consumer = new BufferedByteConsumer(bufferLimit);
+
+         TestFutureCallback callback = new TestFutureCallback();
+         consumer.streamStart(null, callback);
+
+         // Try to add data that exceeds the limit
+         byte[] data = "This is a long string that exceeds the buffer limit".getBytes(StandardCharsets.UTF_8);
+         ByteBuffer buffer = ByteBuffer.wrap(data);
+
+         try {
+             consumer.data(buffer, false);
+             fail("Expected ContentTooLongException");
+         } catch (ContentTooLongException e) {
+             // Verify the exception message contains the expected values
+             assertTrue(e.getMessage().contains("entity content is too long"));
+             assertTrue(e.getMessage().contains(String.valueOf(bufferLimit)));
+         }
+     }
+
+     @Test
+     void testSuccessfulDataConsumption() throws Exception {
+         int bufferLimit = 100;
+         BufferedByteConsumer consumer = new BufferedByteConsumer(bufferLimit);
+
+         TestFutureCallback callback = new TestFutureCallback();
+         consumer.streamStart(null, callback);
+
+         // Add data within the limit
+         byte[] data = "Hello, World!".getBytes(StandardCharsets.UTF_8);
+         ByteBuffer buffer = ByteBuffer.wrap(data);
+
+         consumer.data(buffer, true);
+         consumer.completed();
+
+         // Verify the callback was called successfully
+         assertTrue(callback.isCompleted());
+         assertFalse(callback.isFailed());
+         assertNotNull(consumer.getContent());
+     }
+
+     @Test
+     void testContentAtExactLimit() throws Exception {
+         int bufferLimit = 13;
+         BufferedByteConsumer consumer = new BufferedByteConsumer(bufferLimit);
+
+         consumer.streamStart(null, null);
+
+         // Add data exactly at the limit
+         byte[] data = "Hello, World!".getBytes(StandardCharsets.UTF_8);
+         ByteBuffer buffer = ByteBuffer.wrap(data);
+
+         // Should not throw exception
+         assertDoesNotThrow(() -> consumer.data(buffer, true));
+     }
+
+     @Test
+     void testContentJustOverLimit() throws Exception {
+         int bufferLimit = 12;
+         BufferedByteConsumer consumer = new BufferedByteConsumer(bufferLimit);
+
+         consumer.streamStart(null, null);
+
+         // Add data just over the limit
+         byte[] data = "Hello, World!".getBytes(StandardCharsets.UTF_8);
+         ByteBuffer buffer = ByteBuffer.wrap(data);
+
+         assertThrows(ContentTooLongException.class, () -> consumer.data(buffer, true));
+     }
+
+     @Test
+     void testFailedCallback() {
+         int bufferLimit = 100;
+         BufferedByteConsumer consumer = new BufferedByteConsumer(bufferLimit);
+
+         TestFutureCallback callback = new TestFutureCallback();
+         consumer.streamStart(null, callback);
+
+         Exception testException = new RuntimeException("Test exception");
+         consumer.failed(testException);
+
+         assertTrue(callback.isFailed());
+         assertEquals(testException, callback.getException());
+     }
+
+     private static class TestFutureCallback implements FutureCallback<ByteArrayEntity> {
+         private boolean completed = false;
+         private boolean failed = false;
+         private ByteArrayEntity result;
+         private Exception exception;
+
+         @Override
+         public void completed(ByteArrayEntity result) {
+             this.completed = true;
+             this.result = result;
+         }
+
+         @Override
+         public void failed(Exception ex) {
+             this.failed = true;
+             this.exception = ex;
+         }
+
+         @Override
+         public void cancelled() {
+             // Not used in tests
+         }
+
+         public boolean isCompleted() {
+             return completed;
+         }
+
+         public boolean isFailed() {
+             return failed;
+         }
+
+         public ByteArrayEntity getResult() {
+             return result;
+         }
+
+         public Exception getException() {
+             return exception;
+         }
+     }
+
+}