explanation of test function

Shell Programming and Scripting
1

I have found a code some where, which looks like

if (test $value)
then
<do something>
fi

I am not understanding what is test doing here. I have seen test with !,-eq, -e etc.
But, the above appears to be a new one to me.
Can anyone please expalin me.

2

man test

man test ("test")

3

I have written sort test/if some years ago.

4

with no operator it is "True if string is not empty."

5 
if test $value   # no need to create subprocess 
then 
    doSomething
fi

if  [ $value ]
then
   doSomething
fi

If value is set, then test return exit code 0 = true

# about same, more generic,  documentation is better
if  [ "$value" != "" ]
then
   doSomething
fi