[FLINK-35215][core] Add a test for deserializing an object whose seri…

…alization result is an empty byte array

flink-core/src/test/java/org/apache/flink/testutils/runtime/NoFetchingInputTest.java

@@ -0,0 +1,80 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF 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 org.apache.flink.testutils.runtime;
+
+import org.apache.flink.api.java.typeutils.runtime.NoFetchingInput;
+
+import com.esotericsoftware.kryo.Kryo;
+import com.esotericsoftware.kryo.Serializer;
+import com.esotericsoftware.kryo.io.ByteBufferOutput;
+import com.esotericsoftware.kryo.io.Input;
+import com.esotericsoftware.kryo.io.Output;
+import org.junit.jupiter.api.Test;
+
+import java.io.ByteArrayInputStream;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+/** Tests for the {@link NoFetchingInput}. */
+class NoFetchingInputTest {
+
+    /**
+     * Try deserializing an object whose serialization result is an empty byte array, and don't
+     * expect any exceptions.
+     */
+    @Test
+    void testDeserializeEmptyObject() {
+        EmptyObjectSerializer emptyObjectSerializer = new EmptyObjectSerializer();
+
+        Output output = new ByteBufferOutput(1000);
+        emptyObjectSerializer.write(null, output, new Object());
+
+        Input input = new NoFetchingInput(new ByteArrayInputStream(output.toBytes()));
+        final Object deserialized = emptyObjectSerializer.read(null, input, Object.class);
+
+        assertThat(deserialized).isExactlyInstanceOf(Object.class);
+    }
+
+    /** The serializer that serialize the empty object. */
+    public static class EmptyObjectSerializer extends Serializer<Object> {
+
+        @Override
+        public void write(Kryo kryo, Output output, Object mes) {
+            byte[] ser = new byte[0];
+            output.writeInt(ser.length, true);
+            output.writeBytes(ser);
+        }
+
+        @Override
+        public Object read(Kryo kryo, Input input, Class<Object> pbClass) {
+            try {
+                int size = input.readInt(true);
+                assertThat(size).isZero();
+
+                // Try to read an empty byte array, and don't expect any exception.
+                byte[] barr = new byte[size];
+                input.readBytes(barr);
+
+                return new Object();
+            } catch (Exception e) {
+                throw new RuntimeException("Could not create " + pbClass, e);
+            }
+        }
+    }
+}