diff --git a/components/application-mgt/org.wso2.carbon.device.application.mgt.store.api/src/test/java/org/wso2/carbon/device/application/mgt/store/api/services/CommentManagementAPITest.java b/components/application-mgt/org.wso2.carbon.device.application.mgt.store.api/src/test/java/org/wso2/carbon/device/application/mgt/store/api/services/CommentManagementAPITest.java
index 42ccb83149..cd795abe09 100644
--- a/components/application-mgt/org.wso2.carbon.device.application.mgt.store.api/src/test/java/org/wso2/carbon/device/application/mgt/store/api/services/CommentManagementAPITest.java
+++ b/components/application-mgt/org.wso2.carbon.device.application.mgt.store.api/src/test/java/org/wso2/carbon/device/application/mgt/store/api/services/CommentManagementAPITest.java
@@ -31,7 +31,6 @@ import org.testng.annotations.BeforeClass;
 import org.testng.annotations.ObjectFactory;
 import org.testng.annotations.Test;
 import org.wso2.carbon.device.application.mgt.common.Comment;
-import org.wso2.carbon.device.application.mgt.common.PaginationRequest;
 import org.wso2.carbon.device.application.mgt.common.exception.ApplicationManagementException;
 import org.wso2.carbon.device.application.mgt.common.exception.CommentManagementException;
 import org.wso2.carbon.device.application.mgt.common.services.CommentsManager;
@@ -41,8 +40,6 @@ import org.wso2.carbon.device.application.mgt.store.api.services.util.CommentMgt
 
 import javax.ws.rs.core.Response;
 
-import java.util.List;
-
 import static org.mockito.MockitoAnnotations.initMocks;
 
 @PowerMockIgnore("javax.ws.rs.*")
@@ -80,6 +77,17 @@ public class CommentManagementAPITest {
         Mockito.reset(commentsManager);
     }
 
+    @Test
+    public void testGetAllCommentsInternalError() throws Exception {
+        PowerMockito.stub(PowerMockito.method(APIUtil.class, "getCommentsManager")).toReturn(this.commentsManager);
+        Mockito.doThrow(new CommentManagementException()).when(this.commentsManager).getAllComments(Mockito.any(),Mockito.anyString());
+        Response response = this.commentManagementAPI.getAllComments("a", 1, 4);
+        Assert.assertEquals(response.getStatus(), Response.Status.INTERNAL_SERVER_ERROR.getStatusCode(),
+            "The response status should be 500.");
+        Mockito.reset(commentsManager);
+        Assert.assertNotNull(response, "The response object is null.");
+    }
+
     @Test
     public void testAddComments() throws Exception {
         Comment comment = CommentMgtTestHelper.getDummyComment("a", "a");
@@ -143,6 +151,17 @@ public class CommentManagementAPITest {
             "The response status should be 404.");
     }
 
+    @Test
+    public void testUpdateCommentInternalServerError() throws Exception {
+        Comment comment = CommentMgtTestHelper.getDummyComment("a", "a");
+        PowerMockito.stub(PowerMockito.method(APIUtil.class, "getCommentsManager")).toReturn(this.commentsManager);
+        Mockito.doThrow(new CommentManagementException()).when(this.commentsManager).updateComment(comment, 9);
+        Response response = this.commentManagementAPI.updateComment(comment, 9);
+        Assert.assertNotNull(response, "The response object is null.");
+        Assert.assertEquals(response.getStatus(), Response.Status.INTERNAL_SERVER_ERROR.getStatusCode(),
+            "The response status should be 500.");
+    }
+
     @Test
     public void testDeleteComment() throws Exception {
         PowerMockito.stub(PowerMockito.method(APIUtil.class, "getCommentsManager")).toReturn(this.commentsManager);
@@ -187,7 +206,8 @@ public class CommentManagementAPITest {
     @Test
     public void testGetStarsApplicationError() throws Exception {
         PowerMockito.stub(PowerMockito.method(APIUtil.class, "getCommentsManager")).toReturn(this.commentsManager);
-        Mockito.when(this.commentManagementAPI.getStars(Mockito.anyString())).thenThrow(new ApplicationManagementException());
+        Mockito.when(this.commentManagementAPI.getStars(Mockito.anyString()))
+            .thenThrow(new ApplicationManagementException());
         Response response = this.commentManagementAPI.getStars("a");
         Assert.assertNotNull(response, "The response object is null.");
         Assert.assertEquals(response.getStatus(), Response.Status.INTERNAL_SERVER_ERROR.getStatusCode(),
@@ -208,7 +228,8 @@ public class CommentManagementAPITest {
     @Test
     public void testGetRatedUserCommentError() throws Exception {
         PowerMockito.stub(PowerMockito.method(APIUtil.class, "getCommentsManager")).toReturn(this.commentsManager);
-        Mockito.when(this.commentManagementAPI.getRatedUser(Mockito.anyString())).thenThrow(new CommentManagementException());
+        Mockito.when(this.commentManagementAPI.getRatedUser(Mockito.anyString()))
+            .thenThrow(new CommentManagementException());
         Response response = this.commentManagementAPI.getRatedUser("a");
         Assert.assertNotNull(response, "The response object is null.");
         Assert.assertEquals(response.getStatus(), Response.Status.INTERNAL_SERVER_ERROR.getStatusCode(),
@@ -219,7 +240,8 @@ public class CommentManagementAPITest {
     @Test
     public void testGetRatedUserApplicationError() throws Exception {
         PowerMockito.stub(PowerMockito.method(APIUtil.class, "getCommentsManager")).toReturn(this.commentsManager);
-        Mockito.when(this.commentManagementAPI.getRatedUser(Mockito.anyString())).thenThrow(new ApplicationManagementException());
+        Mockito.when(this.commentManagementAPI.getRatedUser(Mockito.anyString()))
+            .thenThrow(new ApplicationManagementException());
         Response response = this.commentManagementAPI.getRatedUser("a");
         Assert.assertNotNull(response, "The response object is null.");
         Assert.assertEquals(response.getStatus(), Response.Status.INTERNAL_SERVER_ERROR.getStatusCode(),
@@ -247,4 +269,15 @@ public class CommentManagementAPITest {
         Mockito.reset(commentsManager);
     }
 
+    @Test
+    public void testUpdateStarsApplicationError() throws Exception {
+        PowerMockito.stub(PowerMockito.method(APIUtil.class, "getCommentsManager")).toReturn(this.commentsManager);
+        Mockito.doThrow(new ApplicationManagementException()).when(this.commentsManager)
+            .updateStars(Mockito.anyInt(), Mockito.anyString());
+        Response response = this.commentManagementAPI.updateStars(3, "a");
+        Assert.assertNotNull(response, "The response object is null.");
+        Assert.assertEquals(response.getStatus(), Response.Status.INTERNAL_SERVER_ERROR.getStatusCode(),
+            "The response status should be 500.");
+        Mockito.reset(commentsManager);
+    }
 }
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