Demo PR

Account.java

package com.example.demo;

import org.springframework.lang.NonNull;

import java.util.UUID;

public class Account {
    private final UUID id;
    private final String name;

    public Account(@NonNull final UUID id, final String name) {
        this.id = id;
        this.name = name;
    }

    @NonNull
    public UUID getId() {
        return id;
    }

    public String getName() {
        return name;
    }
}

AccountController.java

package com.example.demo;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.PostMapping;
import org.springframework.web.bind.annotation.RequestMapping;

import java.util.List;
import java.util.stream.Collectors;

import static java.util.stream.Collectors.toList;

@Controller()
@RequestMapping("/accounts")
public class AccountController {

    @Autowired
    AccountDao dao;

    public AccountController(AccountDao dao) {
        this.dao = dao;
    }

    // get all accounts
    @GetMapping
    public List<Account> accounts() {
        return dao.getAllAccounts();
    }

    // get all account names
    @GetMapping
    public List<String> accountNames() {
        return dao.getAllAccounts().stream()
                .map(Account::getName)
                .map(String::toUpperCase)
                .collect(toList());
    }

    // get all accounts
    @PostMapping
    public Account createAccount(Account account) {
        return dao.createAccount(account);
    }
}

AccountControllerTest.java

package com.example.demo;

import org.junit.jupiter.api.Test;

import java.lang.reflect.Field;
import java.util.UUID;

import static org.junit.jupiter.api.Assertions.*;
import static org.mockito.Mockito.mock;
import static org.mockito.Mockito.when;

class AccountControllerTest {

    @Test
    public void getAccountName() throws NoSuchFieldException, IllegalAccessException {

        Account a = new Account(UUID.randomUUID(), "Bosse");

        Field privateField = Account.class.getDeclaredField("name");
        privateField.setAccessible(true);

        String name = (String)privateField.get(a);

        assertEquals("Bosse", name);
    }

    @Test
    public void testGetAccountNames() throws Exception {

        Account mockAccount = mock(Account.class);
        UUID rand = UUID.randomUUID();

        when(mockAccount.getName()).thenReturn("Bosse");
        when(mockAccount.getId()).thenReturn(rand);

        AccountDao accountDaoMock = mock(AccountDao.class);
        when(accountDaoMock.getAccountById(rand)).thenReturn(mockAccount);

        String result = accountDaoMock.getUserNameById(1);

        // verify the result
        assertEquals("Bosse", result);
    }
}

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