Using JUnit Tests for Statement Coverage For Method With No Return

I'm new to JUnit testing with Java. I'm trying to do statement coverage over a method, but I don't quite understand how to get it to work when there's no input to the method and no return statement.

Method:

public void applyCost(){
    this.current = this.current - this.Cost.getTotal();
    
    if(this.current > 99f){
        this.current = 99f;
    }
}

My current attempt at the tests:

class applyCostTest {

    @Test
    void testApplyCost() {
        //fail("Not yet implemented");
    }

    public void testLargeCurrent() {
        assertEquals(current = 100f, 99f);
    }
}

I currently get a popup saying that current cannot be resolved to a variable