uitest: Use subtest here

Change-Id: I0e54b950412b4130bb4155d93af2ccafb03d2950
Reviewed-on: https://gerrit.libreoffice.org/38744Tested-by: Jenkins <ci@libreoffice.org>
Reviewed-by: Xisco Faulí <xiscofauli@libreoffice.org>

uitest/writer_tests/insertBreakDialog.py

@@ -56,15 +56,16 @@ class WriterInsertBreakDialog(UITestCase):
         self.ui_test.create_doc_in_start_center("writer")
 
         for i in range(9):
-            xDialog = self.launch_dialog_and_select_option("pagerb")
+            with self.subTest(i=i):
+                xDialog = self.launch_dialog_and_select_option("pagerb")
 
-            xStyleList = xDialog.getChild("stylelb")
-            xStyleList.executeAction("SELECT", mkPropertyValues({"POS": str(i)}))
+                xStyleList = xDialog.getChild("stylelb")
+                xStyleList.executeAction("SELECT", mkPropertyValues({"POS": str(i)}))
 
-            xOkBtn = xDialog.getChild("ok")
-            xOkBtn.executeAction("CLICK", tuple())
+                xOkBtn = xDialog.getChild("ok")
+                xOkBtn.executeAction("CLICK", tuple())
 
-            self.getPages(i + 2)
+                self.getPages(i + 2)
 
         self.ui_test.close_doc()