PHPUnit Framework - Should I include variables in setup() that appear in some but not all functions

Say I have a test file:

ExampleClassTest.php

And the test file has 3 functions:

public function testOne {
     $testVariable = 1;
     // Assert something
}

public function testTwo {
     $testVariable = 1;
     // Assert something
}

public function testThree {
     // Assert something
}

The first two functions have a shared variable:

$testVariable = 1;

How ever the third one does not. Is it good practice to have the shared variable in setup:

setUp() {
     $testVariable = 1;
}

To save repeating code?

Obviously, it is not being used by all functions.

I know it works either way, this is purely from a framework/coding practice perspective.