Working with monetary values

Q. Complete the following “MonetaryProcessingImpl.java” class … so that the unit tests shown below pass? Skeleton code

package com.passing.unittests;

public final class Denomination {

    private long _dollarCount;
    private long _50CentCount;
    private long _20CentCount;
    private long _10CentCount;
    private long _5CentCount;

    public Denomination(long _dollarCount, long _50CentCount, 
                       long _20CentCount, long _10CentCount, long _5CentCount) {
        this._dollarCount = _dollarCount;
        this._50CentCount = _50CentCount;
        this._20CentCount = _20CentCount;
        this._10CentCount = _10CentCount;
        this._5CentCount = _5CentCount;
    }
    
    
    @Override
    public int hashCode() {
        final int prime = 31;
        int result = 1;
        result = prime * result + (int) (_10CentCount ^ (_10CentCount >>> 32));
        result = prime * result + (int) (_20CentCount ^ (_20CentCount >>> 32));
        result = prime * result + (int) (_50CentCount ^ (_50CentCount >>> 32));
        result = prime * result + (int) (_5CentCount ^ (_5CentCount >>> 32));
        result = prime * result + (int) (_dollarCount ^ (_dollarCount >>> 32));
        return result;
    }


    @Override
    public boolean equals(Object obj) {
        if (this == obj)
            return true;
        if (obj == null)
            return false;
        if (getClass() != obj.getClass())
            return false;
        Denomination other = (Denomination) obj;
        if (_10CentCount != other._10CentCount)
            return false;
        if (_20CentCount != other._20CentCount)
            return false;
        if (_50CentCount != other._50CentCount)
            return false;
        if (_5CentCount != other._5CentCount)
            return false;
        if (_dollarCount != other._dollarCount)
            return false;
        return true;
    }

    public long get_dollarCount() {
        return _dollarCount;
    }

    public long get_50CentCount() {
        return _50CentCount;
    }

    public long get_20CentCount() {
        return _20CentCount;
    }

    public long get_10CentCount() {
        return _10CentCount;
    }

    public long get_5CentCount() {
        return _5CentCount;
    }  
}

package com.passing.unittests;

public final class Denomination {

private long _dollarCount;

private long _50CentCount;

private long _20CentCount;

private long _10CentCount;

private long _5CentCount;

public Denomination(long _dollarCount, long _50CentCount,

long _20CentCount, long _10CentCount, long _5CentCount) {

this._dollarCount = _dollarCount;

this._50CentCount = _50CentCount;

this._20CentCount = _20CentCount;

this._10CentCount = _10CentCount;

this._5CentCount = _5CentCount;

}

@Override

public int hashCode() {

final int prime = 31;

int result = 1;

result = prime * result + (int) (_10CentCount ^ (_10CentCount >>> 32));

result = prime * result + (int) (_20CentCount ^ (_20CentCount >>> 32));

result = prime * result + (int) (_50CentCount ^ (_50CentCount >>> 32));

result = prime * result + (int) (_5CentCount ^ (_5CentCount >>> 32));

result = prime * result + (int) (_dollarCount ^ (_dollarCount >>> 32));

return result;

}

@Override

public boolean equals(Object obj) {

if (this == obj)

return true;

if (obj == null)

return false;

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

return false;

Denomination other = (Denomination) obj;

if (_10CentCount != other._10CentCount)

return false;

if (_20CentCount != other._20CentCount)

return false;

if (_50CentCount != other._50CentCount)

return false;

if (_5CentCount != other._5CentCount)

return false;

if (_dollarCount != other._dollarCount)

return false;

return true;

}

public long get_dollarCount() {

return _dollarCount;

}

public long get_50CentCount() {

return _50CentCount;

}

public long get_20CentCount() {

return _20CentCount;

}

public long get_10CentCount() {

return _10CentCount;

}

public long get_5CentCount() {

return _5CentCount;

}

package com.passing.unittests;

import java.math.BigDecimal;
import java.math.RoundingMode;

public interface MonetaryProcessing {
    
    abstract Denomination getDenominations(long amountInCents);
    
    abstract boolean isPositive(BigDecimal amount);

    abstract BigDecimal less(BigDecimal amount, BigDecimal amountToSubtract, boolean ignoreNegativeValue);
    
    abstract BigDecimal divide (BigDecimal input, BigDecimal divisor, RoundingMode roundingMode);
}

package com.passing.unittests;

import java.math.BigDecimal;

import java.math.RoundingMode;

public interface MonetaryProcessing {

abstract Denomination getDenominations(long amountInCents);

abstract boolean isPositive(BigDecimal amount);

abstract BigDecimal less(BigDecimal amount, BigDecimal amountToSubtract, boolean ignoreNegativeValue);

abstract BigDecimal divide (BigDecimal input, BigDecimal divisor, RoundingMode roundingMode);

}

package com.passing.unittests;

import java.math.BigDecimal;
import java.math.RoundingMode;


public class MonetaryProcessingImpl implements MonetaryProcessing {

    public Denomination getDenominations(long amountInCents) {
       return null;
    }

    public boolean isPositive(BigDecimal amount) {
        return false;
    }

    public BigDecimal less(BigDecimal balance, BigDecimal amountToSubtract, boolean ignoreNegativeValue) {
        return null;
    }

    public BigDecimal divide(BigDecimal input, BigDecimal divisor, RoundingMode roundingMode) {
       return null;
    }
   
}

package com.passing.unittests;

import java.math.BigDecimal;

import java.math.RoundingMode;

public class MonetaryProcessingImpl implements MonetaryProcessing {

public Denomination getDenominations(long amountInCents) {

return null;

}

public boolean isPositive(BigDecimal amount) {

return false;

}

public BigDecimal less(BigDecimal balance, BigDecimal amountToSubtract, boolean ignoreNegativeValue) {

return null;

}

public BigDecimal divide(BigDecimal input, BigDecimal divisor, RoundingMode roundingMode) {

return null;

}

The unit test that fails

package com.passing.unittests;

import java.math.BigDecimal;
import java.math.RoundingMode;

import org.junit.Assert;
import org.junit.Before;
import org.junit.Test;

public class MonetaryProcessingTest {

    private MonetaryProcessing mp = null;

    @Before
    public void init() {
        mp = new MonetaryProcessingImpl();
    }

    @Test
    public void testGetDenominations() {
        Denomination denomination = new Denomination(9, 1, 1, 0, 1);
        Assert.assertEquals("Wrong", denomination, mp.getDenominations(975));
    }
    
    @Test(expected=IllegalArgumentException.class)
    public void testNegativeGetDenominations() {
       mp.getDenominations(0);
    }

    
    @Test
    public void testLess() {
        Assert.assertEquals("Wrong", BigDecimal.valueOf(875.00),  
            mp.less(BigDecimal.valueOf(900.00), BigDecimal.valueOf(25.00), false)); 
    }
    
    @Test
    public void testLess2() {
        Assert.assertEquals("Wrong", BigDecimal.valueOf(-925.00),  
            mp.less(BigDecimal.valueOf(-900.00), BigDecimal.valueOf(25.00), false)); 
    }
    
    
    @Test
    public void testLess3() {
        Assert.assertEquals("Wrong", BigDecimal.valueOf(-900.00),  
            mp.less(BigDecimal.valueOf(-900.00), BigDecimal.valueOf(25.00), true)); 
    }
    
    @Test(expected=IllegalArgumentException.class)
    public void testLessNegativeTest() {
        Assert.assertEquals("Wrong", BigDecimal.valueOf(-900.00),  
            mp.less(BigDecimal.valueOf(-900.00), BigDecimal.valueOf(-25.00), true)); 
    }
    
    
    @Test
    public void testDevide() {
        Assert.assertEquals("Wrong", BigDecimal.valueOf(3.14),  
            mp.divide(BigDecimal.valueOf(22.00), BigDecimal.valueOf(7.00), RoundingMode.HALF_EVEN)); 
    }
    
    
    @Test(expected=IllegalArgumentException.class)
    public void testDevideHegativeTest() {
        Assert.assertEquals("Wrong", BigDecimal.valueOf(3.14),  
            mp.divide(BigDecimal.valueOf(22.00), BigDecimal.valueOf(-7.00), RoundingMode.HALF_EVEN)); 
    }  
}

package com.passing.unittests;

import java.math.BigDecimal;

import java.math.RoundingMode;

import org.junit.Assert;

import org.junit.Before;

import org.junit.Test;

public class MonetaryProcessingTest {

private MonetaryProcessing mp = null;

@Before

public void init() {

mp = new MonetaryProcessingImpl();

}

@Test

public void testGetDenominations() {

Denomination denomination = new Denomination(9, 1, 1, 0, 1);

Assert.assertEquals("Wrong", denomination, mp.getDenominations(975));

}

@Test(expected=IllegalArgumentException.class)

public void testNegativeGetDenominations() {

mp.getDenominations(0);

}

@Test

public void testLess() {

Assert.assertEquals("Wrong", BigDecimal.valueOf(875.00),

mp.less(BigDecimal.valueOf(900.00), BigDecimal.valueOf(25.00), false));

}

@Test

public void testLess2() {

Assert.assertEquals("Wrong", BigDecimal.valueOf(-925.00),

mp.less(BigDecimal.valueOf(-900.00), BigDecimal.valueOf(25.00), false));

}

@Test

public void testLess3() {

Assert.assertEquals("Wrong", BigDecimal.valueOf(-900.00),

mp.less(BigDecimal.valueOf(-900.00), BigDecimal.valueOf(25.00), true));

}

@Test(expected=IllegalArgumentException.class)

public void testLessNegativeTest() {

Assert.assertEquals("Wrong", BigDecimal.valueOf(-900.00),

mp.less(BigDecimal.valueOf(-900.00), BigDecimal.valueOf(-25.00), true));

}

@Test

public void testDevide() {

Assert.assertEquals("Wrong", BigDecimal.valueOf(3.14),

mp.divide(BigDecimal.valueOf(22.00), BigDecimal.valueOf(7.00), RoundingMode.HALF_EVEN));

}

@Test(expected=IllegalArgumentException.class)

public void testDevideHegativeTest() {

Assert.assertEquals("Wrong", BigDecimal.valueOf(3.14),

mp.divide(BigDecimal.valueOf(22.00), BigDecimal.valueOf(-7.00), RoundingMode.HALF_EVEN));

}

A. Code that passes the test cases

package com.passing.unittests;

import java.math.BigDecimal;
import java.math.RoundingMode;


public class MonetaryProcessingImpl implements MonetaryProcessing {

    /**
     * the comments are for input of 975  cents
     */
    public Denomination getDenominations(long amountInCents) {
        
        if(amountInCents <= 0){
            throw new IllegalArgumentException("Invalid amount in cents: " + amountInCents);
        }
        
       long varDollarCount, var50CentCount, var20CentCount, var10CentCount, var5CentCount = 0;
       long balance = amountInCents;
       
       varDollarCount = balance/100; //9
       balance = balance%100; // 75
       
       var50CentCount = balance/50;   //1
       balance = balance%50; //25
       
       var20CentCount = balance/20; //1 
       balance = balance%20; //5
       
       var10CentCount = balance/10; //0
       balance = balance%10; //5
       
       var5CentCount = balance/5; //1
       balance = balance%5; //0
       
        
       return new Denomination(varDollarCount, var50CentCount, var20CentCount, var10CentCount, var5CentCount);
    }

    public boolean isPositive(BigDecimal amount) {
        return amount != null && amount.signum() == 1;
    }

    public BigDecimal less(BigDecimal balance, BigDecimal amountToSubtract, boolean ignoreNegativeValue) {
        
        if(amountToSubtract != null && amountToSubtract.signum() == -1){
            throw new IllegalArgumentException("Amount to sbtract cannot be -ve: " + amountToSubtract);
        }
        
        if (isPositive(balance) || !ignoreNegativeValue) {
            balance = balance.subtract(amountToSubtract);
        }
        
        return balance;
    }

    public BigDecimal divide(BigDecimal input, BigDecimal divisor, RoundingMode roundingMode) {
       if(input == null || divisor == null){
           throw new IllegalArgumentException("Invalid input");
       }
       
       if (divisor.compareTo(BigDecimal.ZERO) == 0 || divisor.compareTo(BigDecimal.ZERO) == -1){
           throw new IllegalArgumentException("Divisor cannot be zero or negative: " +  divisor);
       }
       
        return input.divide(divisor, 2, roundingMode);
    }  
}

package com.passing.unittests;

import java.math.BigDecimal;

import java.math.RoundingMode;

public class MonetaryProcessingImpl implements MonetaryProcessing {

/**

* the comments are for input of 975 cents

public Denomination getDenominations(long amountInCents) {

if(amountInCents <= 0){

throw new IllegalArgumentException("Invalid amount in cents: " + amountInCents);

}

long varDollarCount, var50CentCount, var20CentCount, var10CentCount, var5CentCount = 0;

long balance = amountInCents;

varDollarCount = balance/100; //9

balance = balance%100; // 75

var50CentCount = balance/50; //1

balance = balance%50; //25

var20CentCount = balance/20; //1

balance = balance%20; //5

var10CentCount = balance/10; //0

balance = balance%10; //5

var5CentCount = balance/5; //1

balance = balance%5; //0

return new Denomination(varDollarCount, var50CentCount, var20CentCount, var10CentCount, var5CentCount);

}

public boolean isPositive(BigDecimal amount) {

return amount != null && amount.signum() == 1;

}

public BigDecimal less(BigDecimal balance, BigDecimal amountToSubtract, boolean ignoreNegativeValue) {

if(amountToSubtract != null && amountToSubtract.signum() == -1){

throw new IllegalArgumentException("Amount to sbtract cannot be -ve: " + amountToSubtract);

}

if (isPositive(balance) || !ignoreNegativeValue) {

balance = balance.subtract(amountToSubtract);

}

return balance;

}

public BigDecimal divide(BigDecimal input, BigDecimal divisor, RoundingMode roundingMode) {

if(input == null || divisor == null){

throw new IllegalArgumentException("Invalid input");

}

if (divisor.compareTo(BigDecimal.ZERO) == 0 || divisor.compareTo(BigDecimal.ZERO) == -1){

throw new IllegalArgumentException("Divisor cannot be zero or negative: " + divisor);

}

return input.divide(divisor, 2, roundingMode);

}

Key Points Take note that test…

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