Move test to separate test class & add CHANGES entry

Author: Marcono1234

lucene/CHANGES.txt

@@ -239,6 +239,8 @@ Improvements
 
 * GITHUB#15479: Add NumericDocValueRangeQuery base class to add accessor methods for field, lower and upper values (Alan Woodward)
 
+* GITHUB#15570: Disallow invalid offset 0 for LZ4 decompression (Marcono1234)
+
 Optimizations
 ---------------------
 * GITHUB#15140: Optimize TopScoreDocCollector with TernaryLongHeap for improved performance over Binary-LongHeap. (Ramakrishna Chilaka)

lucene/core/src/test/org/apache/lucene/util/compress/LZ4TestCase.java

@@ -384,34 +384,4 @@ public void testUseDictionary() throws IOException {
     // own
     assertTrue(out.size() < len);
   }
-
-  public void testDecompressOffset0() {
-    byte[] input =
-        new byte[] {
-          // token
-          0xE,
-          // offset 0
-          0,
-          0,
-          // last literal
-          // token
-          7 << 4,
-          // literal
-          0,
-          0,
-          0,
-          0,
-          0,
-          0,
-          0
-        };
-
-    byte[] output = new byte[18];
-
-    var e =
-        assertThrows(
-            IOException.class,
-            () -> LZ4.decompress(new ByteArrayDataInput(input), output.length, output, 0));
-    assertEquals("offset 0 is invalid", e.getMessage());
-  }
 }

lucene/core/src/test/org/apache/lucene/util/compress/TestDecompressLZ4.java

@@ -0,0 +1,53 @@
+/*
+ * 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.lucene.util.compress;
+
+import java.io.IOException;
+import org.apache.lucene.store.ByteArrayDataInput;
+import org.apache.lucene.tests.util.LuceneTestCase;
+
+public class TestDecompressLZ4 extends LuceneTestCase {
+  public void testDecompressOffset0() {
+    byte[] input =
+        new byte[] {
+          // token
+          0xE,
+          // offset 0 (invalid)
+          0,
+          0,
+          // last literal
+          // token
+          7 << 4,
+          // literal
+          0,
+          0,
+          0,
+          0,
+          0,
+          0,
+          0
+        };
+
+    byte[] output = new byte[18];
+
+    var e =
+        assertThrows(
+            IOException.class,
+            () -> LZ4.decompress(new ByteArrayDataInput(input), output.length, output, 0));
+    assertEquals("offset 0 is invalid", e.getMessage());
+  }
+}