MathNerdIntegrationTests.java

public void testCacheUpdate() {
    
    //Arrange
    CalculationCache calcCache = new CalculationCache();
    
    Calculator calculator = new Calculator();
    
    MathNerd mathNerd = new MathNerd(calcCache, calculator);
    
    Calculation calcualation = new Calculation("e^2000");
    
    //Act
    mathNerd.doIntenseCalculationInBackground(calculation, null);
    
    //some smelly Thread.sleep() code...
    
    //Assert
    calcCache.contains(calculation);
}