diff --git a/src/test/java/cn/edu/hfut/dmic/contentextractor/ContentExtractorTest.java b/src/test/java/cn/edu/hfut/dmic/contentextractor/ContentExtractorTest.java
new file mode 100644
index 00000000..e5cb0db7
--- /dev/null
+++ b/src/test/java/cn/edu/hfut/dmic/contentextractor/ContentExtractorTest.java
@@ -0,0 +1,78 @@
+package cn.edu.hfut.dmic.contentextractor;
+
+import org.jsoup.nodes.Document;
+import org.junit.Test;
+
+import static org.junit.Assert.*;
+
+/**
+ * Created by LordLRO on 17.09.2019.
+ */
+
+public class ContentExtractorTest {
+    private ContentExtractor contentExtractor = new ContentExtractor(new Document("testUri"));
+
+    @Test
+    public void testStrSim() throws Exception {
+        assertEquals(contentExtractor.strSim("", ""), 0, 0);
+        assertEquals(contentExtractor.strSim("", "abc"), 0, 0);
+        assertEquals(contentExtractor.strSim("132535365", "123456789"), 0.55555555, 0.00000001);
+
+        String longStringOfLetterA = new String(new char[2000000])
+                .replace("\0", "A");
+        assertEquals(contentExtractor
+                .strSim(longStringOfLetterA, "A"), 1.0 /longStringOfLetterA.length(), 0.000001);
+    }
+
+    /**
+     * Test using Robustness Testing skill
+     */
+    @Test public void testLcs() throws Exception {
+        try {
+            assertEquals(contentExtractor.lcs(null, "Hello World!"), 0);
+        }
+        catch (NullPointerException e) {
+        }
+
+        assertEquals(contentExtractor.lcs("", "Hello World!"), 0);
+
+        assertEquals(contentExtractor.lcs("H", "Hello World!"), 1);
+
+        String firstLongString = new String(new char[1000])
+                .replace("\0", "Hello World!");
+        assertEquals(contentExtractor.lcs(firstLongString, "Hello World!"), 12);
+
+        String shorterFirstLongString = new String(new char[1000])
+                .replace("\0", "Hello World");
+        assertEquals(contentExtractor.lcs(shorterFirstLongString, "Hello World!"), 11);
+
+        String longerFirstLongString = new String(new char[1000])
+                .replace("\0", "Hello World!!");
+        assertEquals(contentExtractor.lcs(longerFirstLongString, "Hello World!"), 12);
+
+        try {
+            assertEquals(contentExtractor.lcs("He Word", null), 0);
+        }
+        catch (NullPointerException e) {
+        }
+
+        assertEquals(contentExtractor.lcs("He Word!", ""), 0);
+
+        assertEquals(contentExtractor.lcs("He Word!", "!"), 1);
+
+        String secondLongString = new String(new char[1000])
+                .replace("\0", "He Word!");
+        assertEquals(contentExtractor.lcs(secondLongString, "He Word!"), 8);
+
+        String shorterSecondLongString = new String(new char[1000])
+                .replace("\0", "He Word");
+        assertEquals(contentExtractor.lcs(shorterSecondLongString, "He Word!"), 7);
+
+        String longerSecondLongString = new String(new char[1000])
+                .replace("\0", "!He Word!");
+        assertEquals(contentExtractor.lcs(longerSecondLongString, "He Word!"), 8);
+
+        assertEquals(contentExtractor.lcs("Hello World!", "He Word!"), 8);
+    }
+
+}