Reflection to change value of a private static final field for unit testing.

I'm using the following snippet from this answer .

static void setFinalStatic(Field field, Object newValue) throws Exception {
    field.setAccessible(true);

    // remove final modifier from field
    Field modifiersField = Field.class.getDeclaredField("modifiers");
    modifiersField.setAccessible(true);
    modifiersField.setInt(field, field.getModifiers() & ~Modifier.FINAL);

    field.set(null, newValue);
}

Here's a part of my MyClassTest that calls the above method.(pathToFile is a private static final field in MyClass).

public static void main (String ... args) {
        try{
            setFinalStatic(MyClass.class.getDeclaredField("pathtoFile"), "test-propFile.properties");
            System.out.println(LMSValidation.class.getDeclaredField("pathtoFile"));// prints the original value of pathToFile.
// how do I access the  modified value  pathToFile here?
        }
        catch(Exception e){
            e.printStackTrace();

        }

Also, is doing this, the right approach to unit testing a private static final field? Any comments/suggestions/links appreciated.