Add JAR integration test for JDK compatibility

.github/workflows/test.yml

@@ -63,3 +63,5 @@ jobs:
             export _JAVA_OPTIONS="--enable-native-access=ALL-UNNAMED"
           fi
           ./sbt test
+      - name: JAR Integration Test
+        run: ./script/test-jar-integration.sh

script/test-jar-integration.sh

@@ -0,0 +1,61 @@
+#!/bin/bash
+set -e
+
+echo "=========================================="
+echo "Snappy-Java Integration Test"
+echo "=========================================="
+
+# Detect Java version
+JAVA_VERSION=$(java -version 2>&1 | head -1 | cut -d'"' -f2 | sed 's/^1\.//' | cut -d'.' -f1)
+echo "Java version: $JAVA_VERSION"
+
+# Build the JAR
+echo ""
+echo "Building JAR..."
+./sbt package
+
+# Find the JAR
+JAR_FILE=$(ls -t target/snappy-java-*.jar | grep -v sources | grep -v javadoc | head -1)
+if [ -z "$JAR_FILE" ]; then
+    echo "ERROR: Could not find snappy-java JAR"
+    exit 1
+fi
+echo "Using JAR: $JAR_FILE"
+
+# Create temp directory
+TEMP_DIR=$(mktemp -d)
+echo ""
+echo "Using temp directory: $TEMP_DIR"
+
+# Copy test source
+cp src/test/resources/integration/SnappyIntegrationTest.java "$TEMP_DIR/"
+
+# Compile test
+echo ""
+echo "Compiling test program..."
+javac -cp "$JAR_FILE" -d "$TEMP_DIR" "$TEMP_DIR/SnappyIntegrationTest.java"
+
+# Run test WITHOUT --enable-native-access flag
+echo ""
+echo "=========================================="
+echo "Running test (WITHOUT --enable-native-access flag)..."
+echo "=========================================="
+
+cd "$TEMP_DIR"
+java -cp ".:$OLDPWD/$JAR_FILE" SnappyIntegrationTest 2>&1
+EXIT_CODE=$?
+cd - > /dev/null
+
+echo ""
+echo "=========================================="
+if [ $EXIT_CODE -eq 0 ]; then
+    echo "✓ Test PASSED (exit code: $EXIT_CODE)"
+else
+    echo "✗ Test FAILED (exit code: $EXIT_CODE)"
+fi
+echo "=========================================="
+
+# Cleanup
+rm -rf "$TEMP_DIR"
+
+exit $EXIT_CODE

src/test/resources/integration/SnappyIntegrationTest.java

@@ -0,0 +1,32 @@
+import org.xerial.snappy.Snappy;
+
+/**
+ * Simple integration test to verify snappy-java works in a separate JVM.
+ * This is compiled and run as a standalone program to test the JAR manifest
+ * and native library loading on different JDK versions.
+ */
+public class SnappyIntegrationTest {
+    public static void main(String[] args) throws Exception {
+        String input = "Hello snappy-java! Snappy-java is a JNI-based wrapper of "
+            + "Snappy, a fast compresser/decompresser.";
+
+        // Test compression
+        byte[] compressed = Snappy.compress(input.getBytes("UTF-8"));
+        System.out.println("Compressed " + input.length() + " bytes to " + compressed.length + " bytes");
+
+        // Test decompression
+        byte[] uncompressed = Snappy.uncompress(compressed);
+        String result = new String(uncompressed, "UTF-8");
+
+        // Verify result matches input
+        if (!result.equals(input)) {
+            System.err.println("ERROR: Decompressed data does not match input!");
+            System.err.println("Expected: " + input);
+            System.err.println("Got: " + result);
+            System.exit(1);
+        }
+
+        System.out.println("SUCCESS: " + result);
+        System.exit(0);
+    }
+}