Double quote all variable expansions examples

Eg 1. Variables with meta character value
[wen99999@centOS65 practice]$ mkdir empty;cd empty
[wen99999@centOS65 empty]$ myvar='this is *test*'
[wen99999@centOS65 empty]$ echo $myvar
this is *test*
[wen99999@centOS65 empty]$ touch altest testone
[wen99999@centOS65 empty]$ echo $myvar
this is altest testone
[wen99999@centOS65 empty]$ echo "$myvar"
this is *test*

Eg 2. Variables with null value
[wen99999@centOS65 ~]$ myvar=
[wen99999@centOS65 ~]$ if [ $myvar = something ]; then echo yes; fi
-bash: [: =: unary operator expected
[wen99999@centOS65 ~]$ if [ "$myvar" = something ]; then echo yes; fi