Question

java code

=============

public class BankAccount {
        
        private String accountID;
        private double balance;
        

           /**
              Constructs a bank account with a zero balance
              @param accountID - ID of the Account
           */
           public BankAccount(String accountID)
           {   
              balance = 0;
              this.accountID = accountID;
           }

           /**
              Constructs a bank account with a given balance
              @param initialBalance the initial balance
              @param accountID - ID of the Account
           */
           public BankAccount(double initialBalance, String accountID) 
           {   

                        this.accountID = accountID;
                        balance = initialBalance;
           }
           
           /**
                 * Returns the Account ID
                 * @return the accountID
                 */
                public String getAccountID() {
                        return accountID;
                }
                
                /**
                 * Sets the Account ID
                 * @param accountID
                 */
                public void setAccountID(String accountID) {
                        this.accountID = accountID;
                }

           /**
              Deposits money into the bank account.
              @param amount the amount to deposit
           */
           public void deposit(double amount) 
           {  

                        balance += amount;
           }

           /**
              Withdraws money from the bank account.
              @param amount the amount to withdraw
              @return true if allowed to withdraw
           */
           public boolean withdraw(double amount) 
           {   
                  boolean isAllowed = balance >= amount;
                  if (isAllowed)
                          balance -= amount;
                  return isAllowed;
           }

           /**
              Gets the current balance of the bank account.
              @return the current balance
           */
           public double getBalance()
           {   
              return balance;
           }
          
        }

==========================================

You must write tests for the following:

Unit Testing with JUnit 5

• BankAccount Class
  • Constructing a Bank Account with zero Balance.
  • Constructing a Bank Account with Initial Balance greater than zero.
  • Setting AccountID (AccountID should only accept a string of length 4 with first letter as a character followed by 3 integers, Eg., "A001", is a valid AccountID).
  • Getting AccountID.
  • Depositing an amount in Bank.
  • Withdrawing an amount from bank.
  • Getting balance amount.

Answer 1

import static org.junit.Assert.assertEquals;
import static org.junit.Assert.assertFalse;

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

public class BankAccountTest {

        BankAccount b;
        
        @Before
        public void setup() {
                b = new BankAccount("A123");
        }
        
        @Test
        public void testBadDeposit() {
                double bal = b.getBalance();
                
                try {
                        b.deposit(10001);
                        Assert.fail(); // If we reached here, it means no exception came.
                } catch(Exception e) {
                        // we are good here.
                }
                // the balance should remain same, Because more than 10000 should not be accepted.
                assertEquals(bal, b.getBalance(), 0.000001);
        }
        
        @Test
        public void testLowBalance() {
                double bal = b.getBalance();
                assertFalse(b.withdraw(bal + 100));

                // the balance should remain same, Because it can not be negative.
                assertEquals(bal, b.getBalance(), 0.000001);
        }
        
        @Test
        public void testValidId() {
                
                String ids[] = new String[] {"123", "A", null, "", "AAAA", "a12"};
                
                for(String x: ids) {
                        try {
                                BankAccount ba = new BankAccount(x);
                                Assert.fail(); // If we reached here, it means no exception came.
                        } catch(Exception e) {
                                // we are good here.
                        }
                }
        }
        
        @Test
        public void testBalance() {
                
                String ids[] = new String[] {"123", "A", null, "", "AAAA", "a12"};
                
                for(String x: ids) {
                        try {
                                BankAccount ba = new BankAccount(x);
                                Assert.fail(); // If we reached here, it means no exception came.
                        } catch(Exception e) {
                                // we are good here.
                        }
                }
        }
        
        @Test
        public void testInitialization() {

                try {
                        BankAccount ba = new BankAccount(-2, "A123");
                        Assert.fail(); // If we reached here, it means no exception came.
                } catch(Exception e) {
                        // we are good here.
                }
                
                try {
                        BankAccount ba = new BankAccount(12000, "A123");
                        Assert.fail(); // If we reached here, it means no exception came.
                } catch(Exception e) {
                        // we are good here.
                }
        }
}

class BankAccount {

        private String accountID;
        private double balance;
        
        private void validateId(String accountID) {
                if(accountID == null || accountID.length() != 4 ||
                                !Character.isAlphabetic(accountID.charAt(0)) ||
                                !Character.isDigit(accountID.charAt(1)) ||
                                !Character.isDigit(accountID.charAt(2)) ||
                                !Character.isDigit(accountID.charAt(3))) {
                                throw new IllegalArgumentException("Invalid accountId");
                        }
        }
        /**
         * Constructs a bank account with a zero balance
         * 
         * @param accountID - ID of the Account
         */
        public BankAccount(String accountID) {
                validateId(accountID);
                balance = 0;
                this.accountID = accountID;
        }

        /**
         * Constructs a bank account with a given balance
         * 
         * @param initialBalance the initial balance
         * @param accountID      - ID of the Account
         */
        public BankAccount(double initialBalance, String accountID) {
                validateId(accountID);
                
                if(initialBalance > 10000 || initialBalance < 0) {
                        throw new IllegalArgumentException("Invalid Balance");
                }
                
                this.accountID = accountID;
                balance = initialBalance;
        }

        /**
         * Returns the Account ID
         * 
         * @return the accountID
         */
        public String getAccountID() {
                return accountID;
        }

        /**
         * Sets the Account ID
         * 
         * @param accountID
         */
        public void setAccountID(String accountID) {
                this.accountID = accountID;
        }

        /**
         * Deposits money into the bank account.
         * 
         * @param amount the amount to deposit
         */
        public void deposit(double amount) {
                if(amount > 10000) {
                        throw new IllegalArgumentException("Deposit amount can not be more than 10000");
                }
                balance += amount;
        }

        /**
         * Withdraws money from the bank account.
         * 
         * @param amount the amount to withdraw
         * @return true if allowed to withdraw
         */
        public boolean withdraw(double amount) {
                boolean isAllowed = balance >= amount;
                if (isAllowed)
                        balance -= amount;
                return isAllowed;
        }

        /**
         * Gets the current balance of the bank account.
         * 
         * @return the current balance
         */
        public double getBalance() {
                return balance;
        }

}

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