diff --git a/.gitlab-ci.yml b/.gitlab-ci.yml
index b0b06e39e4539a1ea59da05d6813f9e8bc7d7eb4..3af8920c8f5c38b40be6833e6bdcc69f916bef4c 100644
--- a/.gitlab-ci.yml
+++ b/.gitlab-ci.yml
@@ -76,7 +76,7 @@ test:frontend:
   script: &test_backend_CellDesigner_plugin_definition
 #xvfb is for X11 connection used by some parts of the java code: https://stackoverflow.com/a/47575851/1127920
     - apt-get update
-    - apt-get install -y xvfb
+    - apt-get install -y xvfb libxext6 libxrender1 libxtst6
     - Xvfb :99 &
     - export DISPLAY=:99
 
diff --git a/CellDesigner-plugin/src/test/java/lcsb/mapviewer/cdplugin/info/InfoFrameTest.java b/CellDesigner-plugin/src/test/java/lcsb/mapviewer/cdplugin/info/InfoFrameTest.java
index 320d311eeb797c8b5157de612d705c0b48f80a7b..29aea974375760678eb727ccadec0ce7200446cc 100644
--- a/CellDesigner-plugin/src/test/java/lcsb/mapviewer/cdplugin/info/InfoFrameTest.java
+++ b/CellDesigner-plugin/src/test/java/lcsb/mapviewer/cdplugin/info/InfoFrameTest.java
@@ -7,7 +7,6 @@ import java.util.Arrays;
 import java.util.List;
 
 import org.junit.Test;
-import org.mockito.Mockito;
 
 import jp.sbi.celldesigner.plugin.PluginSpeciesAlias;
 import lcsb.mapviewer.cdplugin.CdPluginFunctions;
@@ -25,8 +24,6 @@ public class InfoFrameTest extends CdPluginFunctions {
   @Test
   public void testSetNotEmptySpeciesList() {
     InfoFrame frame = InfoFrame.getInstance();
-    frame = Mockito.spy(frame);
-    Mockito.doReturn(null).when(frame).getCaptionFont();
     frame.setSpecies(Arrays.asList(super.createSpeciesAlias("id"), super.createSpeciesAlias("id2")));
     assertEquals(2, frame.getSpecies().size());
   }