unit tests cleanup: use testify library for assertions, use cleanup f…

…unction, improve styling

go.mod

@@ -3,9 +3,10 @@ module github.com/trinodb/trino-go-client
 go 1.14
 
 require (
+	github.com/davecgh/go-spew v1.1.1 // indirect
 	github.com/hashicorp/go-uuid v1.0.2 // indirect
 	github.com/jcmturner/gofork v1.0.0 // indirect
-	github.com/stretchr/testify v1.5.1 // indirect
+	github.com/stretchr/testify v1.5.1
 	golang.org/x/crypto v0.0.0-20200221231518-2aa609cf4a9d // indirect
 	gopkg.in/jcmturner/aescts.v1 v1.0.1 // indirect
 	gopkg.in/jcmturner/dnsutils.v1 v1.0.1 // indirect

go.sum

@@ -1,5 +1,6 @@
-github.com/davecgh/go-spew v1.1.0 h1:ZDRjVQ15GmhC3fiQ8ni8+OwkZQO4DARzQgrnXU1Liz8=
 github.com/davecgh/go-spew v1.1.0/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
+github.com/davecgh/go-spew v1.1.1 h1:vj9j/u1bqnvCEfJOwUhtlOARqs3+rkHYY13jYWTU97c=
+github.com/davecgh/go-spew v1.1.1/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
 github.com/hashicorp/go-uuid v1.0.2 h1:cfejS+Tpcp13yd5nYHWDI6qVCny6wyX2Mt5SGur2IGE=
 github.com/hashicorp/go-uuid v1.0.2/go.mod h1:6SBZvOh/SIDV7/2o3Jml5SYk/TvGqwFJ/bN7x4byOro=
 github.com/jcmturner/gofork v1.0.0 h1:J7uCkflzTEhUZ64xqKnkDxq3kzc96ajM1Gli5ktUem8=