Мне самому не нравятся такие тесты, но...?

JournalTest.java

    @Test
    public void testAccountsInitialization() {
        AccountTree.Account expenses;
        assertNotNull( expenses = findAccount("expenses", journal.getRootAccounts()) );
        assertNotNull( findAccount("food", expenses.getChildren()) );
    }

    @Test
    public void testTransactionsInitialization() throws Exception {
        List<Transaction> ts = journal.getTransactions();
        Transaction t;
        assertNotNull(t = findByDateAndDesc("3-13", "first transaction"));

        Map<AccountTree.Account,BigDecimal> postings = t.getPostings();
        AccountTree.Account[] accounts = new AccountTree.Account[2];
        accounts = postings.keySet().toArray(accounts);

        assertEquals("expenses", accounts[0].getName());
        assertEquals("assets", accounts[1].getName());
        assertEquals("10", postings.get(accounts[0]).toString());
        assertNull(postings.get(accounts[1]));
    }