Add some rudimentary tests for DiagramGrid.
Add some rudimentary tests for DiagramGrid.

The goal of having this tests is assuring that DiagramGrid.__new__ is
invoked.  Further tests will come together the corresponding
functionality.

kmacinnis/sympy,jerli/sympy,grevutiu-gabriel/sympy,kevalds51/sympy,sahmed95/sympy,asm666/sympy,beni55/sympy,asm666/sympy,beni55/sympy,Mitchkoens/sympy,bukzor/sympy,grevutiu-gabriel/sympy,asm666/sympy,amitjamadagni/sympy,pandeyadarsh/sympy,lidavidm/sympy,moble/sympy,Gadal/sympy,madan96/sympy,wanglongqi/sympy,MridulS/sympy,toolforger/sympy,skirpichev/omg,yashsharan/sympy,mafiya69/sympy,beni55/sympy,liangjiaxing/sympy,ga7g08/sympy,shipci/sympy,sahilshekhawat/sympy,Curious72/sympy,cswiercz/sympy,jerli/sympy,Davidjohnwilson/sympy,MechCoder/sympy,skidzo/sympy,wyom/sympy,Shaswat27/sympy,kaushik94/sympy,ChristinaZografou/sympy,kumarkrishna/sympy,saurabhjn76/sympy,Curious72/sympy,farhaanbukhsh/sympy,wanglongqi/sympy,abhiii5459/sympy,abloomston/sympy,Designist/sympy,farhaanbukhsh/sympy,shikil/sympy,abloomston/sympy,moble/sympy,aktech/sympy,ChristinaZografou/sympy,emon10005/sympy,pbrady/sympy,VaibhavAgarwalVA/sympy,vipulroxx/sympy,vipulroxx/sympy,oliverlee/sympy,AkademieOlympia/sympy,debugger22/sympy,atreyv/sympy,liangjiaxing/sympy,kmacinnis/sympy,sampadsaha5/sympy,Shaswat27/sympy,hargup/sympy,iamutkarshtiwari/sympy,jaimahajan1997/sympy,Vishluck/sympy,postvakje/sympy,Shaswat27/sympy,yukoba/sympy,mcdaniel67/sympy,ahhda/sympy,Designist/sympy,Titan-C/sympy,atreyv/sympy,AunShiLord/sympy,Arafatk/sympy,aktech/sympy,kumarkrishna/sympy,bukzor/sympy,kevalds51/sympy,jamesblunt/sympy,jbbskinny/sympy,Mitchkoens/sympy,garvitr/sympy,chaffra/sympy,maniteja123/sympy,lindsayad/sympy,kmacinnis/sympy,atsao72/sympy,cccfran/sympy,srjoglekar246/sympy,ChristinaZografou/sympy,hrashk/sympy,emon10005/sympy,iamutkarshtiwari/sympy,mcdaniel67/sympy,pandeyadarsh/sympy,saurabhjn76/sympy,sampadsaha5/sympy,Designist/sympy,postvakje/sympy,lidavidm/sympy,toolforger/sympy,ga7g08/sympy,emon10005/sympy,sahmed95/sympy,debugger22/sympy,flacjacket/sympy,Titan-C/sympy,ahhda/sympy,mafiya69/sympy,dqnykamp/sympy,Davidjohnwilson/sympy,drufat/sympy,maniteja123/sympy,cccfran/sympy,ahhda/sympy,Sumith1896/sympy,AunShiLord/sympy,sunny94/temp,hrashk/sympy,liangjiaxing/sympy,rahuldan/sympy,pbrady/sympy,MridulS/sympy,lindsayad/sympy,dqnykamp/sympy,garvitr/sympy,souravsingh/sympy,jbbskinny/sympy,bukzor/sympy,kaichogami/sympy,atsao72/sympy,wyom/sympy,madan96/sympy,mafiya69/sympy,meghana1995/sympy,debugger22/sympy,shikil/sympy,jaimahajan1997/sympy,hargup/sympy,pandeyadarsh/sympy,lidavidm/sympy,sampadsaha5/sympy,farhaanbukhsh/sympy,Curious72/sympy,shikil/sympy,sahilshekhawat/sympy,abloomston/sympy,chaffra/sympy,Titan-C/sympy,toolforger/sympy,Gadal/sympy,pbrady/sympy,garvitr/sympy,cccfran/sympy,yukoba/sympy,Mitchkoens/sympy,AkademieOlympia/sympy,rahuldan/sympy,chaffra/sympy,sunny94/temp,madan96/sympy,cswiercz/sympy,iamutkarshtiwari/sympy,skidzo/sympy,postvakje/sympy,wyom/sympy,kumarkrishna/sympy,aktech/sympy,vipulroxx/sympy,drufat/sympy,kaichogami/sympy,Sumith1896/sympy,maniteja123/sympy,jerli/sympy,moble/sympy,skidzo/sympy,abhiii5459/sympy,meghana1995/sympy,Vishluck/sympy,Vishluck/sympy,drufat/sympy,Sumith1896/sympy,abhiii5459/sympy,shipci/sympy,atsao72/sympy,hargup/sympy,jamesblunt/sympy,Arafatk/sympy,VaibhavAgarwalVA/sympy,Arafatk/sympy,dqnykamp/sympy,Gadal/sympy,rahuldan/sympy,oliverlee/sympy,kevalds51/sympy,amitjamadagni/sympy,kaushik94/sympy,diofant/diofant,ga7g08/sympy,sahilshekhawat/sympy,jbbskinny/sympy,souravsingh/sympy,saurabhjn76/sympy,mcdaniel67/sympy,souravsingh/sympy,cswiercz/sympy,wanglongqi/sympy,AunShiLord/sympy,MridulS/sympy,kaichogami/sympy,yukoba/sympy,yashsharan/sympy,jamesblunt/sympy,shipci/sympy,sahmed95/sympy,sunny94/temp,MechCoder/sympy,kaushik94/sympy,hrashk/sympy,AkademieOlympia/sympy,yashsharan/sympy,atreyv/sympy,MechCoder/sympy,Davidjohnwilson/sympy,grevutiu-gabriel/sympy,oliverlee/sympy,meghana1995/sympy,jaimahajan1997/sympy,lindsayad/sympy,VaibhavAgarwalVA/sympy