Write tests for the followingYour tests must be written using JUnit $5.$

$-$Customer Class

$$ Constructing a Customer

$$ Getting and setting first and last names

$$ Getting customer number

$$ equals$()$

$$ Checking that the customer number auto$-$increments with each new customer object created

$$ toString$()$

public class Customer $\{$

private static int nextNumber $=1$;

private int number;

private String firstName;

private String lastName;

$/**$

$*$ Represents a customer with customer number $($autogenerated$),$ first and last name.

$*$ @param firstName

$*$ @param lastName

$*/$

public Customer$($String firstName, String lastName$)\{$

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

this.firstName $=$ firstName;

this.lastName $=$ lastName;

$\}$

$/**$

$*$ Returns the first name

$*$ @return the first name

$*/$

public String getFirstName$()\{$

return firstName;

$\}$

$/**$

$*$ Returns the last name

$*$ @return the last name

$*/$

public String getLastName$()\{$

return lastName;

$\}$

$/**$

$*$ Sets the first name

$*$ @param firstName

$*/$

public void setFirstName$($String firstName$)\{$

this.firstName $=$ firstName;

$\}$

$/**$

$*$ Sets the last name

$*$ @param lastName

$*/$

public void setLastName$($String lastName$)\{$

this.lastName $=$ lastName;

$\}$

$/**$

$*$ Returns the customer number

$*$ @return the customer number

$*/$

public int getNumber$()\{$

return number;

$\}$

@Override

public String toString$()\{$

return "Customer $[$number$="+$ number $+",$ name$="+$ firstName $+""+$ lastName $+"]"$;

$\}$

$/**$

$*$ Customers are equal $*$only$*$ if their customer 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;

Customer other $=($Customer$)$ obj;

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

return false;

return true;

$\}$

$\}$