diff --git a/base/test/unittest/common/utils_observer_test.cpp b/base/test/unittest/common/utils_observer_test.cpp
index 208f4f156c8a1149ac3b7c77650a69ece35ae2a8..67da7460cfc82759defd6f965ba395ec96fd6e9b 100644
--- a/base/test/unittest/common/utils_observer_test.cpp
+++ b/base/test/unittest/common/utils_observer_test.cpp
@@ -84,6 +84,21 @@ void UtilsObserverTest::TearDown(void)
 {
 }
 
+/*
+ * @tc.name: test_Observer
+ * @tc.desc: Test add null or repeat observer to the observable object.
+ */
+HWTEST_F(UtilsObserverTest, test_Observer, TestSize.Level0)
+{
+    BookList bookList;
+    bookList.AddObserver(nullptr);
+    shared_ptr<BookObserver> bookObserver1 = make_shared<BookObserver>();
+    bookList.AddObserver(bookObserver1);
+    bookList.AddObserver(bookObserver1);
+    int ret = bookList.GetObserversCount();
+    EXPECT_EQ(ret, 1);
+}
+
 HWTEST_F(UtilsObserverTest, test_ObserverNotify, TestSize.Level0)
 {
     BookList bookList;
@@ -140,4 +155,4 @@ HWTEST_F(UtilsObserverTest, test_RemoveAllObserver, TestSize.Level0)
     EXPECT_EQ(bookList.GetObserversCount(), 0);
 }
 }  // namespace
-}  // namespace OHOS
\ No newline at end of file
+}  // namespace OHOS