Added functions & test cases: deleteAccount and getAllAccounts

src/main/java/bank/Bank.java

@@ -97,4 +97,19 @@ public interface Bank {
      * @return the list of all transactions by type
      */
     List<Transaction> getTransactionsByType(String account, boolean positive);
+
+
+    /**
+     * Delets an existing account
+     * @param account   the account to be deleted
+     * @throws AccountDoesNotExistException
+     * @throws IOException
+     */
+    void deleteAccount(String account) throws AccountDoesNotExistException, IOException;
+
+    /**
+     * Returns a list of all account names
+     * @return
+     */
+    List<String> getAllAccounts();
 }

src/main/java/bank/PrivateBank.java

@@ -354,6 +354,47 @@ public class PrivateBank implements Bank, JsonSerializer<Transaction>, JsonDeser
         return transactions;
     }
 
+    /**
+     * Delets an existing account
+     *
+     * @param account the account to be deleted
+     * @throws AccountDoesNotExistException
+     * @throws IOException
+     */
+    @Override
+    public void deleteAccount(String account) throws AccountDoesNotExistException, IOException {
+        if (this.containsAccount(account)) {
+            // delete account
+            this.accountsToTransactions.remove(account);
+
+            // delete corresponding JSON file
+            String filename = directoryName + "/" + account + ".json";
+            File file = new File(filename);
+            if (!file.delete())
+                throw new IOException();
+        } else {
+            throw new AccountDoesNotExistException();
+        }
+    }
+
+    /**
+     * Returns a list of all account names
+     *
+     * @return List of all accounts
+     */
+    @Override
+    public List<String> getAllAccounts() {
+        List<String> accounts = new ArrayList<>();
+
+        this.accountsToTransactions.forEach(
+                (account, transactions) -> {
+                    accounts.add(account);
+                }
+        );
+
+        return accounts;
+    }
+
     /**
      * Import Accounts from existing JSON Files
      *
@@ -499,4 +540,6 @@ public class PrivateBank implements Bank, JsonSerializer<Transaction>, JsonDeser
 
         return rootObject;
     }
+
+
 }

src/test/java/PrivateBankTest.java

@@ -429,4 +429,67 @@ public class PrivateBankTest {
                 AccountAlreadyExistsException.class, () -> privateBank.readAccounts()
         );
     }
+
+
+    @DisplayName("Delete existing account")
+    @Order(20)
+    @Test
+    public void testDeleteExistingAccount() {
+        assertDoesNotThrow(
+                () -> privateBank.createAccount(
+                        "Konto_X",
+                        List.of(
+                                new OutgoingTransfer(
+                                        "01.01.2000",
+                                        100,
+                                        "OutgoingTransfer to Hans",
+                                        "Konto_X",
+                                        "Hans"
+                                ),
+                                new IncomingTransfer(
+                                        "01.01.2000",
+                                        100,
+                                        "IncomingTransfer from Hans",
+                                        "Hans",
+                                        "Konto_X"
+                                ),
+                                new IncomingTransfer(
+                                        "01.01.2000",
+                                        300,
+                                        "IncomingTransfer from Tom",
+                                        "Tom",
+                                        "Konto_X"
+                                )
+
+                        )
+                )
+        );
+
+        assertDoesNotThrow(
+                () -> privateBank.writeAccount("Konto_X")
+        );
+
+        assertTrue(
+                () -> privateBank.containsAccount("Konto_X")
+        );
+
+        assertDoesNotThrow(
+                () -> privateBank.deleteAccount("Konto_X")
+        );
+
+        assertFalse(
+                () -> privateBank.containsAccount("Konto_X")
+        );
+
+    }
+
+    @DisplayName("Delete non existing account")
+    @Order(21)
+    @Test
+    public void testDeleteNonExistingAccount() {
+        assertThrows(
+                AccountDoesNotExistException.class, () -> privateBank.deleteAccount("Konto_X")
+        );
+    }
+
 }