#include

#include

using namespace std;

class Invoice $\{$

private:

string a;

string b;

int c;

int d;

public:

Invoice$($string pA$,$ string pB$,$ int pC$,$ int pD$)\{$

a $=$ pA;

b $=$ pB;

setC$($pC$)$;

setD$($pD$)$;

$\}$

void setA$($string pA$)\{$

a $=$ pA;

$\}$

void setB$($string pB$)\{$

b $=$ pB;

$\}$

void setC$($int pC$)\{$

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

c $=0$;

$\}$ else $\{$

c $=$ pC;

$\}$

$\}$

void setD$($int pD$)\{$

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

d $=0$;

$\}$ else $\{$

d $=$ pD;

$\}$

$\}$

string getA$()$ const $\{$

return a;

$\}$

string getB$()$ const $\{$

return b;

$\}$

int getC$()$ const $\{$

return c;

$\}$

int getD$()$ const $\{$

return d;

$\}$

int getInvoiceAmount$()$ const $\{$

return c $*$ d;

$\}$

$//$The Copy constructor

Invoice$($const Invoice& other$)\{$

a $=$ other.a;

b $=$ other.b;

c $=$ other.c;

d $=$ other.d;

$\}$

$//$ The Destructor

~Invoice$()\{$

cout $<<$ "Invoice for $"<<$ a $<<"$ is being destroyed." $<<$ endl;

$\}$

$//$ The Clone method

Invoice clone$()$ const $\{$

return Invoice$(*$this$)$;

$\}$

$//$The Overloaded clone method with reference

Invoice clone$($const Invoice& other$)$ const $\{$

return Invoice$($other$)$;

$\}$

$\}$;

use the above code, add:

Task $1\mathrm{.}6$ write a test program to demonstrates class Invoice$$s capabilities defined in

Task $1\mathrm{.}21\mathrm{.}5.$ The test program should follow the unit testing structure introduced at the lecture demos. $($A reference example is on the $$Summary and reference$$ web page on Moodle.$)(10$ points$)$

The main$()$ function should follow the assertion format to print out $$pass$$ or $$fail$$ for each unit test. For example

$//$ unit testing

std:: string message $=$ testArrayAccess$()?$ "passes!": "fails!";

$//$assertion form for calling the unit testing function;

std:: cout $<<$ "The case for array access $"<$ message $<$ std::endl

Finally, it should print out a statistics as $$ m $/$ n pass and k $/$ n fail $$ given the runtime unit test output, where m is the number of pass cases and k is the number of fail cases, and n is the number of total unit testing cases.

For example, if $5$ total number of test cases are invoked in the main$()$ and $5$ cases pass. The program should print out $5/5$ pass and $0/5$ fail$.$