Write tests for the following

$$ Order Class

o Constructing an Order

o Adding a product with non$-$negative quantity to the order

o Removing a product with a non$-$negative quantity from the order

o Checking if a product is in the order

o Checking the quantity of a product in the order

o Getting the total price of the order

o Getting the number of unique products in the order

o Getting the total number of items in the order

public class Order $\{$

private static int nextNumber;

private int number;

private Customer customer;

private Map lines;

$/**$

$*$ Represents an order with an ordernumber $($autogenerated$),$ customer, and order lines with products and quantities.

$*$ @param customer

$*/$

public Order$($Customer customer$)\{$

this.number $=$ nextNumber$++$;

this.customer $=$ customer;

this.lines $=$ new HashMap$()$;

$\}$

$/**$

$*$ Adds a quantity of a product to the order. If the product is already in the order, increase the order quantity by the quantity.

$*$ @param product

$*$ @param quantity must be non$-$negative

$*$ @throws IllegalArgumentException if the quantity is negative

$*/$

public void addToOrder$($Product product, int quantity$)\{$

if $($quantity $<0)\{$

throw new IllegalArgumentException$("$Quantity must be non$-$negative."$)$;

$\}$

if $($lines$.$containsKey$($product$))\{$

lines.put$($product$,$ lines.get$($product$)+$ quantity$)$;

$\}$ else $\{$

lines.put$($product$,$ quantity$)$;

$\}$

$\}$

$/**$

$*$ Remove a quantity of a product from the order. If the product is already in the order, decrease the order quantity by the quantity.

$*$ If the quantity is reduced to zero, remove the product from the order.

$*$ If the product is in the order, return true. If the product is not in the order, return false.

$*$ @param product

$*$ @param quantity must be non$-$negative

$*$ @return true if the product was in the order, false otherwise

$*/$

public boolean removeFromOrder$($Product product, int quantity$)\{$

if $($quantity $<0)\{$

throw new IllegalArgumentException$("$Quantity must be non$-$negative."$)$;

$\}$

if $($lines$.$containsKey$($product$))\{$

if $($lines$.$get$($product$)<=$ quantity$)\{$

lines.remove$($product$)$;

$\}$ else $\{$

lines.put$($product$,$ lines.get$($product$)-$ quantity$)$;

$\}$

return true;

$\}$ else $\{$

return false;

$\}$

$\}$

$/**$

$*$ Determine if a product is in the order

$*$ @param product to check for

$*$ @return whether the product is in the order

$*/$

public boolean contains$($Product product$)\{$

return lines.containsKey$($product$)$;

$\}$

$/**$

$*$ Determine the quantity of a product in the order

$*$ @param product to check

$*$ @return quantity of the product in the order

$*/$

public int getItemQuantity$($Product product$)\{$

if $($contains$($product$))\{$

return lines.get$($product$)$;

$\}$ else $\{$

return $0$;

$\}$

$\}$

$/**$

$*$ Returns the total cost of the order $($unit prices $*$ quantity$)$

$*$ @return the total cost of the order $($unit prices $*$ quantity$)$

$*/$

public double getOrderTotal$()\{$

double total $=0$;

for $($Map$.$Entry entry : lines.entrySet$())\{$

Product key $=$ entry.getKey$()$;

Integer value $=$ entry.getValue$()$;

total $+=$ key.getUnitPrice$()*$ value;

$\}$

return total;

$\}$

$/**$

$*$ Returns the number of order lines.

$*$ @return the number of order lines

$*/$

public int getOrderLineCount$()\{$

return lines.size$()$;

$\}$

$/**$

$*$ Returns the number of items in the order $($sum of quantity of all lines$)$

$*$ @returnthe number of items in the order $($sum of quantity of all lines$)$

$*/$

public int getOrderItemCount$()\{$

int total $=0$;

for $($Map$.$Entry entry : lines.entrySet$())\{$

total $+=$ entry.getValue$()$;

$\}$

return total;

$\}$

@Override

public String toString$()\{$

return "Order $[$number$="+$ number $+",$ customer$="+$ customer $+",$ lines$="+$ lines $+"]"$;

$\}$

$/**$

$*$ Orders are equal $*$only$*$ if their order numbers are equal

$*$ @see java.lang.Object#equals$($java$.$lang.Object$)$

$*/$

@Override

public boolean equals$($Object obj$)\{$

if $($this $==$ obj$)$

return true;

if $($obj $==$ null$)$

return false;

if $($getClass$()!=$ obj.getClass$())$

return false;

Order other $=($Order$)$ obj;

if $($number $!=$ other.number$)$

return false;

return true;

$\}$

$\}$