diff --git a/webmagic-core/src/test/java/us/codecraft/webmagic/utils/CharsetUtilsTest.java b/webmagic-core/src/test/java/us/codecraft/webmagic/utils/CharsetUtilsTest.java
new file mode 100644
index 0000000..987a6f7
--- /dev/null
+++ b/webmagic-core/src/test/java/us/codecraft/webmagic/utils/CharsetUtilsTest.java
@@ -0,0 +1,16 @@
+package us.codecraft.webmagic.utils;
+
+import static org.junit.jupiter.api.Assertions.assertNull;
+
+import java.io.IOException;
+
+import org.junit.jupiter.api.Test;
+
+class CharsetUtilsTest {
+
+    @Test
+    void testDetectCharset() throws IOException {
+        assertNull(CharsetUtils.detectCharset(null, new byte[0]));
+    }
+
+}