Tests edited to support versions <= 2.0
Tests edited to support versions <= 2.0

abinashmeher999/symengine.rb,abinashmeher999/symengine.rb,rajithv/symengine.rb,rajithv/symengine.rb,isuruf/symengine.rb,rajithv/symengine.rb,isuruf/symengine.rb,abinashmeher999/symengine.rb,symengine/symengine.rb,isuruf/symengine.rb,symengine/symengine.rb,symengine/symengine.rb