Added tests for has_callback() function
Added tests for has_callback() function

rajul/ginga,rajul/ginga,rajul/ginga,pllim/ginga,ejeschke/ginga,Cadair/ginga,naojsoft/ginga,Cadair/ginga,naojsoft/ginga,pllim/ginga,Cadair/ginga,stscieisenhamer/ginga,pllim/ginga,rupak0577/ginga,naojsoft/ginga,rupak0577/ginga,stscieisenhamer/ginga,stscieisenhamer/ginga,ejeschke/ginga,rupak0577/ginga,ejeschke/ginga