Add case withdraw 0 sum for ATM task solutions. Unify name of method param

Author: andrei-punko

src/main/java/by/andd3dfx/common/ATM.java

@@ -45,10 +45,10 @@ public Map<Integer, Integer> withdraw(int amount) {
         throw new IllegalStateException("Could not perform withdraw!");
     }
 
-    private Map<Integer, Integer> withdraw(int amount, int startingBanknoteIndex) {
+    private Map<Integer, Integer> withdraw(int amount, int nominalIndex) {
         var result = new HashMap<Integer, Integer>();
 
-        for (var index = startingBanknoteIndex; index < nominals.size(); index++) {
+        for (var index = nominalIndex; index < nominals.size(); index++) {
             var nominal = nominals.get(index);
             if (nominal > amount || state.get(nominal) == 0) {
                 continue;
@@ -57,7 +57,6 @@ private Map<Integer, Integer> withdraw(int amount, int startingBanknoteIndex) {
             int count = amount / nominal;
             count = Math.min(count, state.get(nominal));
             result.put(nominal, count);
-
             amount -= nominal * count;
 
             if (amount == 0) {

src/main/java/by/andd3dfx/common/ATM2.java

@@ -46,6 +46,9 @@ public Map<Integer, Integer> withdraw(int amount) {
     }
 
     private Map<Integer, Integer> withdraw(int amount, int nominalIndex) {
+        if (amount == 0) {
+            return Map.of();
+        }
         if (nominalIndex >= nominals.size()) {
             throw new IllegalStateException("Could not perform withdraw!");
         }

src/test/java/by/andd3dfx/common/ATM2Test.java

@@ -21,6 +21,14 @@ public void setUp() throws Exception {
         ));
     }
 
+    @Test
+    public void withdrawFor0() {
+        var result = atm.withdraw(0);
+
+        assertThat(result).isEqualTo(Map.of(
+        ));
+    }
+
     @Test
     public void withdraw() {
         var result = atm.withdraw(450);

src/test/java/by/andd3dfx/common/ATMTest.java

@@ -21,6 +21,14 @@ public void setUp() throws Exception {
         ));
     }
 
+    @Test
+    public void withdrawFor0() {
+        var result = atm.withdraw(0);
+
+        assertThat(result).isEqualTo(Map.of(
+        ));
+    }
+
     @Test
     public void withdraw() {
         var result = atm.withdraw(450);