add test to make sure only one x axis is non-deleted in exported doc

Change-Id: I8172015668cc43b4383276f2cd20cce4b0704277

chart2/qa/extras/chart2export.cxx

@@ -1457,6 +1457,7 @@ void Chart2ExportTest::testMultipleAxisXLSX()
     assertXPath(pXmlDoc, "/c:chartSpace/c:chart/c:plotArea/c:scatterChart[1]/c:ser", 1);
     assertXPath(pXmlDoc, "/c:chartSpace/c:chart/c:plotArea/c:scatterChart[2]/c:ser", 1);
     assertXPath(pXmlDoc, "/c:chartSpace/c:chart/c:plotArea/c:valAx", 4);
+    assertXPath(pXmlDoc, "/c:chartSpace/c:chart/c:plotArea/c:valAx/c:delete[@val='1']", 1);
 }
 
 CPPUNIT_TEST_SUITE_REGISTRATION(Chart2ExportTest);