Please develop Junit tests for at least $3$ of the methods in class ArrayOperations. Try to reach $100\%$ statement coverage and $100\%$ branch coverage.

package inclass;

public class ArrayOperations

$\{$

$//$ Adapted from "Introduction to Software Testing",

$//$ by Ammann and Offutt

public static int numZero$($int$[]$ x$)$

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$//$ Effects: if x $==$ null throw NullPointerException

$//$ else return the number of occurrences of $0$ in x

int count $=0$;

for $($int i$=1$; i$0$; i$--)$

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if $($x$[$i$]==$ y$)$

return i;

$\}$

return $-1$;

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$//$ test: x $=[2,3,5]$; y $=2$;

$//$ expected $=0$

public static int countPositive $($int$[]$ x$)$

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if $($x $==$ null$)$

throw new NullPointerException$()$;

int count $=0$;

for $($int i$=0$; i$=0)$

count$++$;

$\}$

return count;

$\}$

$//$ test: x $=[-4,2,0,2]$

$//$ expected $=2$

public static int lastZero $($int$[]$ x$)$

$\{$

if $($x $==$ null$)$

throw new NullPointerException$()$;

for $($int i$=0$; i $0)$

count$++$;

$\}$

return count;

$\}$

$//$ test: x $=[-3,-2,0,1,4]$

$//$ expected $=3$

$\}$