An algorithm for our company's dishwasher. Because people need instructions.

DishwasherAlgo.java

public class Dishwasher {

  public enum StatusCode { READY_TO_WASH, WASHING, READY_TO_EMPTY }
	public enum Reason { OK, FULL, MUST_REMOVE_DISHES, MUST_EXECUTE_WASH_CYCLE }
	
	public Integer capacity {get; set;} // 0 - 100
	public StatusCode status {get; set;}
	public hasSoap {get; set;}
	
	public Dishwasher() {
		this.capacity = 0;
	}
	
	public String addDish(Dish dirtyDish) {
		Reason addDishMessage = Reason.OK;
	
		// Can we add a dish?
		Reason canAddMessage = this.canAdd(dirtyDish);
		
		if (canAddMessage != Reason.OK) {
			addDishMessage = canAddMessage;
			return addDishMessage;
		}
	
		// We can add a dish, so add it.
		this.capacity += dirtyDish.getSizeCode();
		
		// Are we full?
		if (this.capacity >= 97)
			addDishMessage = Reason.FULL;
		
		return addDishMessage;
	}

	public Reason canAdd(Dish dirtyDish) {
		Reason resultReason = Reason.OK;
		
		if (this.status == StatusCode.WASHING)
			resultReason = Reason.IS_WASHING;
		if (this.status == StatusCode.READY_TO_EMPTY)
			resultReason = Reason.MUST_REMOVE_DISHES;
		
		if (resultReason != Reason.OK)
			return resultReason;
		
		if (this.capacity + dirtyDish.getSizeCode() > 100)
			resultReason = Reason.MUST_EXECUTE_WASH_CYCLE;
		
		return resultReason;
	}
	
	public Boolean executeWashCycle() {
		if (this.hasSoap == false)
			return false;
		
		this.status = StatusCode.WASHING;
		// * Washing dishes *
		this.status = StatusCode.READY_TO_EMPTY;
		
		return true;
	}

}


public class Dish {

	public enum SizeCode { S, M, L }
	public SizeCode sizeCode {get; set;}
	
	public Dish(SizeCode sizeCode) {
		this.sizeCode = sizeCode'
	}
	
	public Integer getSize() {
		if (this.sizeCode == SizeCode.S)
			return 1;
		else if (this.sizeCode == SizeCode.M)
			return 2;
		else if (this.sizeCode == SizeCode.L)
			return 3;
	}

}


public class Sink {
	
	public addDish() {
		throw new Exception('Sink is for rinsing. Please add dish to a Dishwasher.');
	}
	
}


public class TestDishwasherInteraction {

	public void testMethod testDirtyDish_AddToSink_ShouldError() {
		// Create test data
		Dish dirtyCup = new Dish(SizeCode.S);		
		Sink fourthFloorSink = new Sink();
		
		// Can we add a dirty dish to the sink?
		String sinkError = '';
		try {
			// Invoke functionality
			fourthFloorSink.addDish(dirtyCup);
		}
		catch (Exception e) {
			sinkError = e.getMessage();
		}
		
		// Check results
		System.assert(sinkError.contains('add dish to a Dishwasher')); // No!
	}
	
	public void testMethod testDirtyDish_AddToEmptyDishwasher_ShouldAccept() {
		// Create test data
		Dish dirtyCup = new Dish(SizeCode.S);
		Dishwasher fourthFloorDishwasher = new Dishwasher();
		
		// Can we add a dirty dish to an empty dishwasher?
		// Invoke functionality
		Dishwasher.Reason addMessage = fourthFloorDishwasher.addDish(dirtyCup);
		
		// Check results
		System.assertEquals(Reason.OK, addMessage); // Yes!
	}
	
	public void testMethod testDirtyDish_AddToFullDishwasher_ShouldFail() {
		// Create test data
		Dish dirtyCup = new Dish(SizeCode.S);
		Dishwasher fourthFloorDishwasher = new Dishwasher();
		fourthFloorDishwasher.capacity = 100;
		
		// Can we add a dirty dish to a full dishwasher?
		// Invoke functionality
		Dishwasher.Reason addMessage = fourthFloorDishwasher.addDish(dirtyCup);
		
		// Check results
		System.assertEquals(Dishwasher.Reason.MUST_EXECUTE_WASH_CYCLE, addMessage);
	}
	
	public void testMethod testDirtyDish_HasSoap_RunDishwasher_ShouldComplete() {
		//Create test data
		Dishwasher fourthFloorDishwasher = new Dishwasher();
		fourthFloorDishwasher.hasSoap = true;
		
		//Invoke functionality
		Boolean isCycleComplete = fourthFloorDishwasher.executeWashCycle();
		
		// Check results
		System.assertEquals(true, isCycleComplete);
	}
}