示例#1
0
 def test_identical_thresholds(self):
     """ Test the min/max thresholds can be the same. """
     strategy = AllocationStrategy(self.method,
                                   1,
                                   min_equity=0.5,
                                   max_equity=0.5)
     self.assertEqual(strategy.min_equity, strategy.max_equity)
示例#2
0
    def test_strategy_n_minus_age_unadj(self):
        """ Test strategy_n_minus_age with early retirement, unadjusted. """
        # Finally, try n=120 without adjusting the retirement age to
        # confirm that max_equity is respected.
        method = AllocationStrategy.strategy_n_minus_age
        target = 120
        standard_retirement_age = 65
        retirement_age = standard_retirement_age - 20
        strategy = AllocationStrategy(method,
                                      target,
                                      min_equity=0,
                                      max_equity=1,
                                      standard_retirement_age=65,
                                      risk_transition_period=10,
                                      adjust_for_retirement_plan=False)

        for age in range(0, 20):
            self.assertAlmostEqual(strategy(age).stocks, strategy.max_equity)
            self.assertAlmostEqual(
                strategy(age).bonds, 1 - strategy.max_equity)
        for age in range(20, target):
            self.assertAlmostEqual(
                strategy(age, retirement_age=retirement_age).stocks,
                (target - age) / 100)
            self.assertAlmostEqual(
                strategy(age, retirement_age=retirement_age).bonds,
                1 - (target - age) / 100)
        for age in range(target, target + 100):
            self.assertAlmostEqual(
                strategy(age, retirement_age=retirement_age).stocks,
                strategy.min_equity)
            self.assertAlmostEqual(
                strategy(age, retirement_age=retirement_age).bonds,
                1 - strategy.min_equity)
示例#3
0
    def test_strategy_trans_to_const(self):
        """ Test AllocationStrategy.strategy_transition_to_constant. """
        method = AllocationStrategy.strategy_transition_to_const

        # Create a basic strategy that transitions from 100% stocks to
        # 50% stocks between the ages of 55 and 65.
        strategy = AllocationStrategy(method,
                                      0.5,
                                      min_equity=0,
                                      max_equity=1,
                                      standard_retirement_age=65,
                                      risk_transition_period=10,
                                      adjust_for_retirement_plan=False)

        for age in range(18, 54):
            self.assertAlmostEqual(strategy(age).stocks, 1)
            self.assertAlmostEqual(strategy(age).bonds, 0)
        for age in range(55, 65):
            self.assertAlmostEqual(
                strategy(age).stocks,
                1 * (65 - age) / 10 + 0.5 * (age - 55) / 10)
            self.assertAlmostEqual(
                strategy(age).bonds,
                1 - (1 * (65 - age) / 10 + 0.5 * (age - 55) / 10))
        for age in range(66, 100):
            self.assertAlmostEqual(strategy(age).stocks, 0.5)
            self.assertAlmostEqual(strategy(age).bonds, 0.5)
示例#4
0
    def test_strategy_n_minus_age_dec(self):
        """ Test strategy_n_minus_age with Decimal inputs. """
        method = AllocationStrategy.strategy_n_minus_age

        # Create a basic strategy that puts 100-age % into equity
        target = 100
        strategy = AllocationStrategy(method,
                                      target,
                                      min_equity=0,
                                      max_equity=1,
                                      standard_retirement_age=65,
                                      risk_transition_period=10,
                                      adjust_for_retirement_plan=False,
                                      high_precision=Decimal)

        # Test allocations for each age from birth to retirement:
        for age in range(0, target):
            self.assertAlmostEqual(
                strategy(age).stocks, Decimal((target - age) / 100))
            self.assertAlmostEqual(
                strategy(age).bonds, Decimal(1 - (target - age) / 100))
        # Test allocations for each age from retirement onward:
        for age in range(target, target + 100):
            self.assertAlmostEqual(strategy(age).stocks, strategy.min_equity)
            self.assertAlmostEqual(
                strategy(age).bonds, 1 - strategy.min_equity)
示例#5
0
    def test_strategy_n_minus_age_early(self):
        """ Test strategy_n_minus_age with early retirement. """
        method = AllocationStrategy.strategy_n_minus_age
        # Try with adjustments for retirement plans enabled.
        # Use n = 120, but a retirement age that's 20 years early.
        # After adjusting for retirement plans, the results should be
        # the same as in the above test
        target = 120
        standard_retirement_age = 65
        diff = -20
        retirement_age = standard_retirement_age + diff
        strategy = AllocationStrategy(method,
                                      target,
                                      min_equity=0,
                                      max_equity=1,
                                      standard_retirement_age=65,
                                      risk_transition_period=10,
                                      adjust_for_retirement_plan=True)

        for age in range(0, target + diff):
            self.assertAlmostEqual(
                strategy(age, retirement_age=retirement_age).stocks,
                (target + diff - age) / 100)
            self.assertAlmostEqual(
                strategy(age, retirement_age=retirement_age).bonds,
                1 - (target + diff - age) / 100)
        for age in range(target + diff, target + diff + 100):
            self.assertAlmostEqual(
                strategy(age, retirement_age=retirement_age).stocks,
                strategy.min_equity)
            self.assertAlmostEqual(
                strategy(age, retirement_age=retirement_age).bonds,
                1 - strategy.min_equity)
示例#6
0
    def setUp_decimal(self):
        """ Sets up variables based on Decimal inputs. """
        # We use caps because this is a type.
        # pylint: disable=invalid-name
        self.AccountType = Account
        # pylint: enable=invalid-name

        # It's important to synchronize the initial years of related
        # objects, so store it here:
        self.initial_year = 2000
        # Every init requires an owner, so store that here:
        self.scenario = Scenario(inflation=Decimal(0),
                                 stock_return=Decimal(1),
                                 bond_return=Decimal(0.5),
                                 other_return=Decimal(0),
                                 management_fees=Decimal(0.03125),
                                 initial_year=self.initial_year,
                                 num_years=100)
        self.allocation_strategy = AllocationStrategy(
            strategy=AllocationStrategy.strategy_n_minus_age,
            min_equity=Decimal(0.5),
            max_equity=Decimal(0.5),
            target=Decimal(0.5),
            standard_retirement_age=65,
            risk_transition_period=20,
            adjust_for_retirement_plan=False)
        self.owner = Person(
            self.initial_year,
            "test",
            2000,
            raise_rate={year: Decimal(1)
                        for year in range(2000, 2066)},
            retirement_date=2065)

        # We'll also need a timing value for various tests.
        # Use two inflows, at the start and end, evenly weighted:
        self.timing = {Decimal(0): Decimal(1), Decimal(1): Decimal(1)}

        # Inheriting classes should assign to self.account with an
        # instance of an appropriate subclass of Account.
        self.account = Account(self.owner,
                               balance=Decimal(100),
                               rate=Decimal(1.0),
                               high_precision=Decimal)
示例#7
0
    def test_init_decimal(self):
        """ Test AllocationStrategy.__init__ with Decimal inputs."""
        # Arguments for AllocationStrategy are:
        # strategy (str, func)
        # min_equity (Decimal)
        # max_equity (Decimal)
        # target (Decimal)
        # standard_retirement_age (int)
        # risk_transition_period (int)
        # adjust_for_retirement_plan (bool)
        # Test explicit init:
        method = AllocationStrategy.strategy_n_minus_age
        min_equity = 0
        max_equity = 1
        target = '0.5'
        standard_retirement_age = 65.0
        risk_transition_period = '10'
        adjust_for_retirement_plan = 'Evaluates to True'
        strategy = AllocationStrategy(
            method,
            target,
            min_equity=min_equity,
            max_equity=max_equity,
            standard_retirement_age=standard_retirement_age,
            risk_transition_period=risk_transition_period,
            adjust_for_retirement_plan=adjust_for_retirement_plan,
            high_precision=Decimal)
        # Pylint misses this member, which is added by metaclass
        # pylint: disable=no-member
        self.assertEqual(strategy.strategy, method.strategy_key)
        # pylint: enable=no-member
        self.assertEqual(strategy.min_equity, Decimal(min_equity))
        self.assertEqual(strategy.max_equity, Decimal(max_equity))
        self.assertEqual(strategy.target, Decimal(target))
        self.assertEqual(strategy.standard_retirement_age,
                         int(standard_retirement_age))
        self.assertEqual(strategy.risk_transition_period,
                         int(risk_transition_period))
        self.assertEqual(strategy.adjust_for_retirement_plan,
                         bool(adjust_for_retirement_plan))

        # Type-check:
        self.assertIsInstance(strategy.strategy, str)
        self.assertIsInstance(strategy.min_equity, Decimal)
        self.assertIsInstance(strategy.max_equity, Decimal)
        self.assertIsInstance(strategy.target, Decimal)
        self.assertIsInstance(strategy.standard_retirement_age, int)
        self.assertIsInstance(strategy.risk_transition_period, int)
        self.assertIsInstance(strategy.adjust_for_retirement_plan, bool)
示例#8
0
    def test_init_default(self):
        """ Test AllocationStrategy.__init__ with default params."""
        # Arguments for AllocationStrategy are:
        # strategy (str, func)
        # min_equity (float)
        # max_equity (float)
        # target (float)
        # standard_retirement_age (int)
        # risk_transition_period (int)
        # adjust_for_retirement_plan (bool)

        # Test default init:
        method = AllocationStrategy.strategy_n_minus_age
        strategy = AllocationStrategy(method, 100)
        # pylint: disable=no-member
        self.assertEqual(strategy.strategy, method.strategy_key)
        self.assertAlmostEqual(strategy.min_equity, 0)
        self.assertAlmostEqual(strategy.max_equity, 1)
        # The default target varies depending on the strategy
        self.assertAlmostEqual(strategy.target, 100)
        self.assertAlmostEqual(strategy.standard_retirement_age, 65)
        self.assertAlmostEqual(strategy.risk_transition_period, 20)
        self.assertAlmostEqual(strategy.adjust_for_retirement_plan, True)
示例#9
0
 def test_mismatched_thresholds(self):
     """ Tests mismatched min and max equity thresholds. """
     with self.assertRaises(ValueError):
         _ = AllocationStrategy(self.method, 1, min_equity=1, max_equity=0)
示例#10
0
 def setUp(self):
     # Provide default method/strategy for testing:
     self.method = AllocationStrategy.strategy_n_minus_age
     self.strategy = AllocationStrategy(self.method, 100)
示例#11
0
 def test_invalid_strategies(self):
     """ Tests that invalid strategies raise exceptions. """
     with self.assertRaises(ValueError):
         _ = AllocationStrategy(strategy='Not a strategy', target=1)
示例#12
0
    def test_strategy_n_minus_age(self):
        """ Test AllocationStrategy.strategy_n_minus_age. """
        method = AllocationStrategy.strategy_n_minus_age

        # Create a basic strategy that puts 100-age % into equity
        target = 100
        strategy = AllocationStrategy(method,
                                      target,
                                      min_equity=0,
                                      max_equity=1,
                                      standard_retirement_age=65,
                                      risk_transition_period=10,
                                      adjust_for_retirement_plan=False)

        for age in range(0, target):
            self.assertAlmostEqual(
                strategy(age).stocks, Decimal((target - age) / 100))
            self.assertAlmostEqual(
                strategy(age).bonds, Decimal(1 - (target - age) / 100))
        for age in range(target, target + 100):
            self.assertEqual(strategy(age).stocks, strategy.min_equity)
            self.assertEqual(strategy(age).bonds, 1 - strategy.min_equity)

        # Try with adjustments for retirement plans enabled.
        # Use n = 120, but a retirement age that's 20 years early.
        # After adjusting for retirement plans, the results should be
        # the same as in the above test
        target = 120
        standard_retirement_age = 65
        diff = -20
        retirement_age = standard_retirement_age + diff
        strategy = AllocationStrategy(method,
                                      target,
                                      min_equity=0,
                                      max_equity=1,
                                      standard_retirement_age=65,
                                      risk_transition_period=10,
                                      adjust_for_retirement_plan=True)

        for age in range(0, target + diff):
            self.assertAlmostEqual(
                strategy(age, retirement_age=retirement_age).stocks,
                Decimal((target + diff - age) / 100))
            self.assertAlmostEqual(
                strategy(age, retirement_age=retirement_age).bonds,
                Decimal(1 - (target + diff - age) / 100))
        for age in range(target + diff, target + diff + 100):
            self.assertEqual(
                strategy(age, retirement_age=retirement_age).stocks,
                strategy.min_equity)
            self.assertEqual(
                strategy(age, retirement_age=retirement_age).bonds,
                1 - strategy.min_equity)

        # Finally, try n=120 without adjusting the retirement age to
        # confirm that max_equity is respected.
        target = 120
        standard_retirement_age = 65
        retirement_age = standard_retirement_age - 20
        strategy = AllocationStrategy(method,
                                      target,
                                      min_equity=0,
                                      max_equity=1,
                                      standard_retirement_age=65,
                                      risk_transition_period=10,
                                      adjust_for_retirement_plan=False)

        for age in range(0, 20):
            self.assertEqual(strategy(age).stocks, strategy.max_equity)
            self.assertEqual(strategy(age).bonds, 1 - strategy.max_equity)
        for age in range(20, target):
            self.assertAlmostEqual(
                strategy(age, retirement_age=retirement_age).stocks,
                Decimal((target - age) / 100))
            self.assertAlmostEqual(
                strategy(age, retirement_age=retirement_age).bonds,
                Decimal(1 - (target - age) / 100))
        for age in range(target, target + 100):
            self.assertEqual(
                strategy(age, retirement_age=retirement_age).stocks,
                strategy.min_equity)
            self.assertEqual(
                strategy(age, retirement_age=retirement_age).bonds,
                1 - strategy.min_equity)
示例#13
0
    def test_init(self):
        """ Test AllocationStrategy.__init__ """
        # Arguments for AllocationStrategy are:
        # strategy (str, func)
        # min_equity (Decimal)
        # max_equity (Decimal)
        # target (Decimal)
        # standard_retirement_age (int)
        # risk_transition_period (int)
        # adjust_for_retirement_plan (bool)

        # Test default init:
        method = AllocationStrategy.strategy_n_minus_age
        strategy = AllocationStrategy(method, 100)
        # pylint: disable=no-member
        self.assertEqual(strategy.strategy, method.strategy_key)
        self.assertEqual(strategy.min_equity, 0)
        self.assertEqual(strategy.max_equity, 1)
        # The default target varies depending on the strategy
        self.assertEqual(strategy.target, 100)
        self.assertEqual(strategy.standard_retirement_age, 65)
        self.assertEqual(strategy.risk_transition_period, 20)
        self.assertEqual(strategy.adjust_for_retirement_plan, True)

        # Test explicit init:
        method = AllocationStrategy.strategy_n_minus_age
        min_equity = 0
        max_equity = 1
        target = '0.5'
        standard_retirement_age = 65.0
        risk_transition_period = '10'
        adjust_for_retirement_plan = 'Evaluates to True'
        strategy = AllocationStrategy(
            method,
            target,
            min_equity=min_equity,
            max_equity=max_equity,
            standard_retirement_age=standard_retirement_age,
            risk_transition_period=risk_transition_period,
            adjust_for_retirement_plan=adjust_for_retirement_plan)
        self.assertEqual(strategy.strategy, method.strategy_key)
        self.assertEqual(strategy.min_equity, Decimal(min_equity))
        self.assertEqual(strategy.max_equity, Decimal(max_equity))
        self.assertEqual(strategy.target, Decimal(target))
        self.assertEqual(strategy.standard_retirement_age,
                         int(standard_retirement_age))
        self.assertEqual(strategy.risk_transition_period,
                         int(risk_transition_period))
        self.assertEqual(strategy.adjust_for_retirement_plan,
                         bool(adjust_for_retirement_plan))

        # Type-check:
        self.assertIsInstance(strategy.strategy, str)
        self.assertIsInstance(strategy.min_equity, Decimal)
        self.assertIsInstance(strategy.max_equity, Decimal)
        self.assertIsInstance(strategy.target, Decimal)
        self.assertIsInstance(strategy.standard_retirement_age, int)
        self.assertIsInstance(strategy.risk_transition_period, int)
        self.assertIsInstance(strategy.adjust_for_retirement_plan, bool)

        # Test invalid strategies
        with self.assertRaises(ValueError):
            strategy = AllocationStrategy(strategy='Not a strategy', target=1)
        with self.assertRaises(TypeError):
            strategy = AllocationStrategy(strategy=1, target=1)
        # Test invalid min_equity (Decimal)
        with self.assertRaises(decimal.InvalidOperation):
            strategy = AllocationStrategy(method, 1, min_equity='invalid')
        # Test invalid max_equity (Decimal)
        with self.assertRaises(decimal.InvalidOperation):
            strategy = AllocationStrategy(method, 1, max_equity='invalid')
        # Test invalid target (Decimal)
        with self.assertRaises(decimal.InvalidOperation):
            strategy = AllocationStrategy(method, target='invalid')
        # Test invalid standard_retirement_age (int)
        with self.assertRaises(ValueError):
            strategy = AllocationStrategy(method,
                                          1,
                                          standard_retirement_age='invalid')
        # Test invalid risk_transition_period (int)
        with self.assertRaises(ValueError):
            strategy = AllocationStrategy(method,
                                          1,
                                          risk_transition_period='invalid')
        # No need to test invalid adjust_for_retirement_plan (bool)

        # Test mismatched min and max equity thresholds
        with self.assertRaises(ValueError):
            strategy = AllocationStrategy(method,
                                          1,
                                          min_equity=1,
                                          max_equity=0)
        # Confirm that the thresholds *can* be the same:
        strategy = AllocationStrategy(method,
                                      1,
                                      min_equity=0.5,
                                      max_equity=0.5)
        self.assertEqual(strategy.min_equity, strategy.max_equity)
示例#14
0
    def setUp_decimal(self):
        """ Builds default strategies/persons/etc. with Decimal inputs. """
        # pylint: disable=invalid-name
        # This name is based on `setUp`, which doesn't follow Pylint's rules
        # pylint: enable=invalid-name

        # Use a default settings object:
        # (This is conditional so that subclasses can assign their own
        # settings object before calling super().setUp())
        if not hasattr(self, 'settings'):
            self.settings = Settings()

        # To simplify tests, modify Settings so that forecasts are
        # just 2 years with easy-to-predict contributions ($1000/yr)
        self.settings.num_years = 2
        self.settings.living_expenses_strategy = (
            LivingExpensesStrategy.strategy_const_contribution)
        self.settings.living_expenses_base_amount = Decimal(1000)

        # Allow subclasses to use subclasses of Forecaster by assigning
        # to forecaster_type
        if not hasattr(self, 'forecaster_type'):
            self.forecaster_type = Forecaster

        # Build default `SubForecast` inputs based on `settings`:
        self.initial_year = self.settings.initial_year
        self.scenario = Scenario(
            inflation=Decimal(self.settings.inflation),
            stock_return=Decimal(self.settings.stock_return),
            bond_return=Decimal(self.settings.bond_return),
            other_return=Decimal(self.settings.other_return),
            management_fees=Decimal(self.settings.management_fees),
            initial_year=self.settings.initial_year,
            num_years=self.settings.num_years)
        self.living_expenses_strategy = LivingExpensesStrategy(
            strategy=self.settings.living_expenses_strategy,
            base_amount=Decimal(self.settings.living_expenses_base_amount),
            rate=Decimal(self.settings.living_expenses_rate),
            inflation_adjust=self.scenario.inflation_adjust)
        self.saving_strategy = TransactionStrategy(
            strategy=self.settings.saving_strategy,
            weights={
                year: Decimal(val)
                for (year, val) in self.settings.saving_weights.items()
            })
        self.withdrawal_strategy = TransactionStrategy(
            strategy=self.settings.withdrawal_strategy,
            weights={
                year: Decimal(val)
                for (year, val) in self.settings.withdrawal_weights.items()
            })
        self.allocation_strategy = AllocationStrategy(
            strategy=self.settings.allocation_strategy,
            min_equity=Decimal(self.settings.allocation_min_equity),
            max_equity=Decimal(self.settings.allocation_max_equity),
            target=Decimal(self.settings.allocation_target),
            standard_retirement_age=(
                self.settings.allocation_std_retirement_age),
            risk_transition_period=self.settings.allocation_risk_trans_period,
            adjust_for_retirement_plan=(
                self.settings.allocation_adjust_retirement))
        self.debt_payment_strategy = DebtPaymentStrategy(
            strategy=self.settings.debt_payment_strategy,
            high_precision=Decimal)
        self.tax_treatment = Tax(
            tax_brackets={
                year: {
                    Decimal(lower): Decimal(upper)
                }
                for (year, vals) in self.settings.tax_brackets.items()
                for (lower, upper) in vals.items()
            },
            personal_deduction={
                year: Decimal(val)
                for (year,
                     val) in self.settings.tax_personal_deduction.items()
            },
            credit_rate={
                year: Decimal(val)
                for (year, val) in self.settings.tax_credit_rate.items()
            },
            inflation_adjust=self.scenario.inflation_adjust,
            high_precision=Decimal)

        # Now build some Ledger objects to test against:
        # A person making $10,000/yr
        self.person = Person(initial_year=self.initial_year,
                             name="Test 1",
                             birth_date="1 January 1980",
                             retirement_date="31 December 2040",
                             gross_income=Decimal(10000),
                             raise_rate=Decimal(0),
                             spouse=None,
                             tax_treatment=self.tax_treatment,
                             high_precision=Decimal)
        # An account with $1000 in it (and no interest)
        self.account = Account(owner=self.person,
                               balance=Decimal(1000),
                               high_precision=Decimal)
        # A debt with a $100 balance (and no interest)
        self.debt = Debt(owner=self.person,
                         balance=Decimal(100),
                         high_precision=Decimal)

        # Init a Forecaster object here for convenience:
        self.forecaster = self.forecaster_type(settings=self.settings,
                                               high_precision=Decimal)
示例#15
0
    def setUp(self):
        """ Builds default strategies, persons, etc. """
        # Use a default settings object:
        # (This is conditional so that subclasses can assign their own
        # settings object before calling super().setUp())
        if not hasattr(self, 'settings'):
            self.settings = Settings()

        # To simplify tests, modify Settings so that forecasts are
        # just 2 years with easy-to-predict contributions ($1000/yr)
        self.settings.num_years = 2
        self.settings.living_expenses_strategy = (
            LivingExpensesStrategy.strategy_const_contribution)
        self.settings.living_expenses_base_amount = 1000

        # Allow subclasses to use subclasses of Forecaster by assigning
        # to forecaster_type
        if not hasattr(self, 'forecaster_type'):
            self.forecaster_type = Forecaster

        # Build default `SubForecast` inputs based on `settings`:
        self.initial_year = self.settings.initial_year
        self.scenario = Scenario(inflation=self.settings.inflation,
                                 stock_return=self.settings.stock_return,
                                 bond_return=self.settings.bond_return,
                                 other_return=self.settings.other_return,
                                 management_fees=self.settings.management_fees,
                                 initial_year=self.settings.initial_year,
                                 num_years=self.settings.num_years)
        self.living_expenses_strategy = LivingExpensesStrategy(
            strategy=self.settings.living_expenses_strategy,
            base_amount=self.settings.living_expenses_base_amount,
            rate=self.settings.living_expenses_rate,
            inflation_adjust=self.scenario.inflation_adjust)
        self.saving_strategy = TransactionStrategy(
            strategy=self.settings.saving_strategy,
            weights=self.settings.saving_weights)
        self.withdrawal_strategy = TransactionStrategy(
            strategy=self.settings.withdrawal_strategy,
            weights=self.settings.withdrawal_weights)
        self.allocation_strategy = AllocationStrategy(
            strategy=self.settings.allocation_strategy,
            min_equity=self.settings.allocation_min_equity,
            max_equity=self.settings.allocation_max_equity,
            target=self.settings.allocation_target,
            standard_retirement_age=(
                self.settings.allocation_std_retirement_age),
            risk_transition_period=self.settings.allocation_risk_trans_period,
            adjust_for_retirement_plan=(
                self.settings.allocation_adjust_retirement))
        self.debt_payment_strategy = DebtPaymentStrategy(
            strategy=self.settings.debt_payment_strategy)
        self.tax_treatment = Tax(
            tax_brackets=self.settings.tax_brackets,
            personal_deduction=self.settings.tax_personal_deduction,
            credit_rate=self.settings.tax_credit_rate,
            inflation_adjust=self.scenario.inflation_adjust)

        # Now build some Ledger objects to test against:
        # A person making $10,000/yr
        self.person = Person(initial_year=self.initial_year,
                             name="Test 1",
                             birth_date="1 January 1980",
                             retirement_date="31 December 2040",
                             gross_income=10000,
                             raise_rate=0,
                             spouse=None,
                             tax_treatment=self.tax_treatment)
        # An account with $1000 in it (and no interest)
        self.account = Account(owner=self.person, balance=1000)
        # A debt with a $100 balance (and no interest)
        self.debt = Debt(owner=self.person, balance=100)

        # Init a Forecaster object here for convenience:
        self.forecaster = self.forecaster_type(settings=self.settings)
示例#16
0
class TestAccountMethods(unittest.TestCase):
    """ A test suite for the `Account` class.

    For each Account subclass, create a test case that subclasses from
    this (or an intervening subclass). Then, in the setUp method,
    assign to class attributes `args`, and/or `kwargs` to
    determine which arguments will be prepended, postpended, or added
    via keyword when an instance of the subclass is initialized.
    Don't forget to also assign the subclass your're testing to
    `self.AccountType`, and to run `super().setUp()` at the top!

    This way, the methods of this class will still be called even for
    subclasses with mandatory positional arguments. You should still
    override the relevant methods to test subclass-specific logic (e.g.
    if the subclass modifies the treatment of the `rate` attribute
    based on an init arg, you'll want to test that by overriding
    `test_rate`)
    """
    def setUp(self):
        """ Sets up some class-specific variables for calling methods. """
        # We use caps because this is a type.
        # pylint: disable=invalid-name
        self.AccountType = Account
        # pylint: enable=invalid-name

        # It's important to synchronize the initial years of related
        # objects, so store it here:
        self.initial_year = 2000
        # Every init requires an owner, so store that here:
        self.scenario = Scenario(inflation=0,
                                 stock_return=1,
                                 bond_return=0.5,
                                 other_return=0,
                                 management_fees=0.03125,
                                 initial_year=self.initial_year,
                                 num_years=100)
        self.allocation_strategy = AllocationStrategy(
            strategy=AllocationStrategy.strategy_n_minus_age,
            min_equity=Decimal(0.5),
            max_equity=Decimal(0.5),
            target=Decimal(0.5),
            standard_retirement_age=65,
            risk_transition_period=20,
            adjust_for_retirement_plan=False)
        self.owner = Person(self.initial_year,
                            "test",
                            2000,
                            raise_rate={year: 1
                                        for year in range(2000, 2066)},
                            retirement_date=2065)

        # We'll also need a timing value for various tests.
        # Use two inflows, at the start and end, evenly weighted:
        self.timing = {Decimal(0): 1, Decimal(1): 1}

        # Inheriting classes should assign to self.account with an
        # instance of an appropriate subclass of Account.
        self.account = Account(self.owner, balance=100, rate=1.0)

    def test_init_basic(self, *args, **kwargs):
        """ Tests Account.__init__ """
        # Basic test: All correct values, check for equality and type
        owner = self.owner
        balance = Money(0)
        rate = 1.0
        nper = 1  # This is the easiest case to test
        initial_year = self.initial_year
        account = self.AccountType(owner,
                                   *args,
                                   balance=balance,
                                   rate=rate,
                                   nper=nper,
                                   **kwargs)
        # Test primary attributes
        # pylint: disable=no-member
        # Pylint is confused by members added by metaclass
        self.assertEqual(account.balance_history, {initial_year: balance})
        self.assertEqual(account.rate_history, {initial_year: rate})
        self.assertEqual(account.transactions_history, {initial_year: {}})
        self.assertEqual(account.balance, balance)
        self.assertEqual(account.rate, rate)
        self.assertEqual(account.nper, 1)
        self.assertEqual(account.initial_year, initial_year)
        self.assertEqual(account.this_year, initial_year)

        # Check types
        # pylint: disable=no-member
        # Pylint is confused by members added by metaclass
        self.assertTrue(type_check(account.balance_history, {int: Money}))
        self.assertIsInstance(account.balance, Money)
        self.assertTrue(type_check(account.rate_history, {int: Decimal}))
        self.assertIsInstance(account.rate, Decimal)
        self.assertIsInstance(account.nper, int)
        self.assertIsInstance(account.initial_year, int)

    def test_init_rate_function(self, *args, **kwargs):
        """ Tests using a function as an input for arg `rate`. """
        # Infer the rate from the account owner's asset allocation
        # (which is 50% stocks, 50% bonds, with 75% return overall)
        # pylint: disable=no-member
        # Pylint is confused by members added by metaclass
        balance = 0
        rate = self.allocation_strategy.rate_function(self.owner,
                                                      self.scenario)
        account = self.AccountType(self.owner,
                                   *args,
                                   balance=balance,
                                   rate=rate,
                                   **kwargs)
        self.assertEqual(account.balance_history, {self.initial_year: balance})
        self.assertEqual(account.transactions_history, {self.initial_year: {}})
        self.assertEqual(account.balance, balance)
        self.assertEqual(account.rate, Decimal(0.75))
        self.assertEqual(account.rate_history,
                         {self.initial_year: Decimal(0.75)})
        self.assertEqual(account.transactions, {})
        self.assertEqual(account.nper, 1)
        self.assertEqual(account.initial_year, self.initial_year)
        self.assertEqual(account.rate_callable, rate)

    def test_init_type_conversion(self, *args, **kwargs):
        """ Tests using (Decimal-convertible) strings as input. """
        balance = "0"
        rate = "1.0"
        nper = 'A'
        initial_year = self.initial_year
        account = self.AccountType(self.owner,
                                   *args,
                                   balance=balance,
                                   rate=rate,
                                   nper=nper,
                                   **kwargs)
        # pylint: disable=no-member
        # Pylint is confused by members added by metaclass
        self.assertEqual(account.balance_history, {initial_year: Money(0)})
        self.assertEqual(account.rate_history, {initial_year: 1})
        self.assertEqual(account.transactions_history, {initial_year: {}})
        self.assertEqual(account.balance, Money(0))
        self.assertEqual(account.rate, 1)
        self.assertEqual(account.nper, 1)
        self.assertEqual(account.initial_year, initial_year)
        # Check types for conversion
        self.assertIsInstance(account.balance_history[initial_year], Money)
        self.assertIsInstance(account.rate_history[initial_year], Decimal)
        self.assertIsInstance(account.nper, int)
        self.assertIsInstance(account.initial_year, int)

    def test_init_invalid_balance(self, *args, **kwargs):
        """ Test Account.__init__ with invalid balance input. """
        # Let's test invalid Decimal conversions next.
        # (BasicContext causes most Decimal-conversion errors to raise
        # exceptions. Invalid input will raise InvalidOperation)
        decimal.setcontext(decimal.BasicContext)

        # Test with values not convertible to Decimal
        with self.assertRaises(decimal.InvalidOperation):
            account = self.AccountType(self.owner,
                                       *args,
                                       balance="invalid input",
                                       **kwargs)
            # In some contexts, Decimal returns NaN instead of raising an error
            if account.balance == Money("NaN"):
                raise decimal.InvalidOperation()

    def test_init_invalid_rate(self, *args, **kwargs):
        """ Test Account.__init__ with invalid rate input. """
        decimal.setcontext(decimal.BasicContext)
        with self.assertRaises(decimal.InvalidOperation):
            account = self.AccountType(self.owner,
                                       *args,
                                       balance=0,
                                       rate="invalid input",
                                       **kwargs)
            # `rate` is not callable if we use non-callable input
            # pylint: disable=comparison-with-callable
            if account.rate == Decimal("NaN"):
                raise decimal.InvalidOperation()
            # pylint: enable=comparison-with-callable

    def test_init_invalid_owner(self, *args, **kwargs):
        """ Test Account.__init__ with invalid rate input. """
        # Finally, test passing an invalid owner:
        with self.assertRaises(TypeError):
            _ = self.AccountType("invalid owner", *args, **kwargs)

    def test_add_trans_in_range(self):
        """ Test 'when' values inside of the range [0,1]. """
        self.account.add_transaction(1, when=0)
        self.assertEqual(self.account.transactions[Decimal(0)], Money(1))

        self.account.add_transaction(1, when=0.5)
        self.assertEqual(self.account.transactions[Decimal(0.5)], Money(1))

        self.account.add_transaction(1, when=1)
        self.assertEqual(self.account.transactions[Decimal(1)], Money(1))

    def test_add_trans_out_range(self):
        """ Test 'when' values outside of the range [0,1]. """
        # All of these should raise exceptions.
        with self.assertRaises(ValueError):  # test negative
            self.account.add_transaction(1, when=-1)
        with self.assertRaises(ValueError):  # test positive
            self.account.add_transaction(1, when=2)

    def test_returns(self, *args, **kwargs):
        """ Tests Account.returns and Account.returns_history. """
        # Account with $1 balance and 100% non-compounded growth.
        # Should have returns of $1 in its first year:
        account = self.AccountType(self.owner,
                                   *args,
                                   balance=1,
                                   rate=1.0,
                                   nper=1,
                                   **kwargs)
        # pylint: disable=no-member
        # Pylint is confused by members added by metaclass
        self.assertEqual(account.returns, Money(1))  # $1 return
        self.assertEqual(account.returns_history,
                         {self.initial_year: Money(1)})

    def test_returns_next_year(self, *args, **kwargs):
        """ Tests Account.returns after calling next_year. """
        # Account with $1 balance and 100% non-compounded growth.
        # Should have returns of $2 in its second year:
        account = self.AccountType(self.owner,
                                   *args,
                                   balance=1,
                                   rate=1.0,
                                   nper=1,
                                   **kwargs)
        account.next_year()
        # pylint: disable=no-member
        # Pylint is confused by members added by metaclass
        self.assertEqual(account.returns_history, {
            self.initial_year: Money(1),
            self.initial_year + 1: Money(2)
        })
        self.assertEqual(account.returns, Money(2))

    def test_next(self, *args, **kwargs):
        """ Tests next_year with basic scenario. """
        # Simple account: Start with $1, apply 100% growth once per
        # year, no transactions. Should yield a new balance of $2.
        account = self.AccountType(self.owner,
                                   *args,
                                   balance=1,
                                   rate=1.0,
                                   nper=1,
                                   **kwargs)
        account.next_year()
        self.assertEqual(account.balance, Money(2))

    def test_next_no_growth(self, *args, **kwargs):
        """ Tests next_year with no growth. """
        # Start with $1 and apply 0% growth.
        account = self.AccountType(self.owner,
                                   *args,
                                   balance=1,
                                   rate=0,
                                   **kwargs)
        account.next_year()
        self.assertEqual(account.balance, Money(1))

    def test_next_cont_growth(self, *args, **kwargs):
        """ Tests next_year with continuous growth. """
        account = self.AccountType(self.owner,
                                   *args,
                                   balance=1,
                                   rate=1,
                                   nper='C',
                                   **kwargs)
        account.next_year()
        self.assertAlmostEqual(account.balance, Money(math.e), 3)

    def test_next_disc_growth(self, *args, **kwargs):
        """ Tests next_year with discrete (monthly) growth. """
        account = self.AccountType(self.owner,
                                   *args,
                                   balance=1,
                                   rate=1,
                                   nper='M',
                                   **kwargs)
        account.next_year()
        self.assertAlmostEqual(account.balance, Money((1 + 1 / 12)**12), 3)

    def test_next_basic_trans(self, *args, **kwargs):
        """ Tests next_year with a mid-year transaction. """
        # Start with $1 (which grows to $2), contribute $2 mid-year.
        # NOTE: The growth of the $2 transaction is not well-defined,
        # since it occurs mid-compounding-period. However, the output
        # should be sensible. In  particular, it should grow by $0-$1.
        # So check to confirm that the result is in the range [$4, $5]
        account = self.AccountType(self.owner,
                                   *args,
                                   balance=1,
                                   rate=1.0,
                                   nper=1,
                                   **kwargs)
        account.add_transaction(Money(2), when='0.5')
        account.next_year()
        self.assertGreaterEqual(account.balance, Money(4))
        self.assertLessEqual(account.balance, Money(5))

    def test_next_no_growth_trans(self, *args, **kwargs):
        """ Tests next_year with no growth and a transaction. """
        # Start with $1, add $2, and apply 0% growth.
        account = self.AccountType(self.owner,
                                   *args,
                                   balance=1,
                                   rate=0,
                                   nper=1,
                                   **kwargs)
        account.add_transaction(Money(2), when='0.5')
        account.next_year()
        self.assertEqual(account.balance, Money(3))

    def test_next_cont_growth_trans(self, *args, **kwargs):
        """ Tests next_year with continuous growth and a transaction. """
        # This can be calculated from P = P_0 * e^rt
        account = self.AccountType(self.owner,
                                   *args,
                                   balance=1,
                                   rate=1,
                                   nper='C',
                                   **kwargs)
        account.add_transaction(Money(2), when='0.5')
        next_val = Money(1 * math.e + 2 * math.e**0.5)
        account.next_year()
        self.assertAlmostEqual(account.balance, next_val, 5)

    def test_next_disc_growth_trans(self, *args, **kwargs):
        """ Tests next_year with discrete growth and a transaction. """
        # The $2 transaction happens at the start of a compounding
        # period, so behaviour is well-defined. It should grow by a
        # factor of (1 + r/n)^nt, for n = 12 (monthly) and t = 0.5
        account = self.AccountType(self.owner,
                                   *args,
                                   balance=1,
                                   rate=1,
                                   nper='M',
                                   **kwargs)
        account.add_transaction(Money(2), when='0.5')
        next_val = Money((1 + 1 / 12)**(12) + 2 * (1 + 1 / 12)**(12 * 0.5))
        account.next_year()
        self.assertAlmostEqual(account.balance, next_val, 5)

    def test_add_trans(self, *args, **kwargs):
        """ Tests add_transaction. """
        # Start with an empty account and add a transaction.
        # pylint: disable=no-member
        # Pylint is confused by members added by metaclass
        account = self.AccountType(self.owner, *args, **kwargs)
        self.assertEqual(account.transactions_history, {self.initial_year: {}})
        account.add_transaction(Money(1), when='end')
        self.assertEqual(account.transactions_history,
                         {self.initial_year: {
                             1: Money(1)
                         }})
        self.assertEqual(account.transactions, {1: Money(1)})
        self.assertEqual(account.inflows(), Money(1))

    def test_add_trans_mult_diff_time(self, *args, **kwargs):
        """ Tests add_transaction with transactions at different times. """
        account = self.AccountType(self.owner, *args, **kwargs)
        account.add_transaction(Money(1), 'start')
        account.add_transaction(Money(2), 1)
        self.assertEqual(account.transactions, {0: Money(1), 1: Money(2)})
        self.assertEqual(account.inflows(), Money(3))
        self.assertEqual(account.outflows(), Money(0))

    def test_add_trans_mult_same_time(self, *args, **kwargs):
        """ Tests add_transaction with transactions at the same time. """
        account = self.AccountType(self.owner, *args, **kwargs)
        account.add_transaction(Money(1), 'start')
        account.add_transaction(Money(1), 0)
        self.assertEqual(account.transactions, {0: Money(2)})
        self.assertEqual(account.inflows(), Money(2))
        self.assertEqual(account.outflows(), Money(0))

    def test_add_trans_diff_in_out(self, *args, **kwargs):
        """ Tests add_transaction with in- and outflows at different times. """
        account = self.AccountType(self.owner, *args, **kwargs)
        account.add_transaction(Money(1), 'start')
        account.add_transaction(Money(-2), 'end')
        self.assertEqual(account.transactions, {0: Money(1), 1: Money(-2)})
        self.assertEqual(account.inflows(), Money(1))
        self.assertEqual(account.outflows(), Money(-2))

    def test_add_trans_same_in_out(self, *args, **kwargs):
        """ Tests add_transaction with simultaneous inflows and outflows. """
        # NOTE: Consider whether this behaviour (i.e. simultaneous flows
        # being combined into one net flow) should be revised.
        account = self.AccountType(self.owner, *args, **kwargs)
        account.add_transaction(Money(1), 'start')
        account.add_transaction(Money(-2), 'start')
        self.assertEqual(account.transactions, {0: Money(-1)})
        self.assertEqual(account.inflows(), 0)
        self.assertEqual(account.outflows(), Money(-1))

        # TODO: Test add_transactions again after performing next_year
        # (do this recursively?)

    def test_max_outflows_constant(self, *args, **kwargs):
        """ Test max_outflows with constant-balance account """
        # Simple scenario: $100 in a no-growth account with no
        # transactions. Should return $100 for any point in time.
        account = self.AccountType(self.owner,
                                   *args,
                                   balance=100,
                                   rate=0,
                                   nper=1,
                                   **kwargs)
        result = account.max_outflows(self.timing)
        for when, value in result.items():
            account.add_transaction(value, when=when)
        # Result of `max_outflows` should bring balance to $0 if
        # applied as transactions:
        self.assertAlmostEqual(account.balance_at_time('end'), Money(0))

    def test_max_outflows_negative(self, *args, **kwargs):
        """ Test max_outflows with negative-balance account. """
        # Try with negative balance - should return $0
        account = self.AccountType(self.owner,
                                   *args,
                                   balance=-100,
                                   rate=1,
                                   nper=1,
                                   **kwargs)
        result = account.max_outflows(self.timing)
        for value in result.values():
            self.assertAlmostEqual(value, Money(0), places=4)

    def test_max_outflows_simple(self, *args, **kwargs):
        """ Test max_outflows with simple growth, no transactions """
        # $100 in account that grows to $200 in one compounding period.
        # No transactions.
        account = self.AccountType(self.owner,
                                   *args,
                                   balance=100,
                                   rate=1,
                                   nper=1,
                                   **kwargs)
        result = account.max_outflows(self.timing)
        for when, value in result.items():
            account.add_transaction(value, when=when)
        # Result of `max_outflows` should bring balance to $0 if
        # applied as transactions:
        self.assertAlmostEqual(account.balance_at_time('end'),
                               Money(0),
                               places=4)

    def test_max_outflows_simple_trans(self, *args, **kwargs):
        """ Test max_outflows with simple growth and transactions """
        # $100 in account that grows linearly by 100%. Add $100
        # transactions at the start and end of the year.
        account = self.AccountType(self.owner,
                                   *args,
                                   balance=100,
                                   rate=1,
                                   nper=1,
                                   **kwargs)
        account.add_transaction(100, when='start')
        account.add_transaction(100, when='end')
        result = account.max_outflows(self.timing)
        for when, value in result.items():
            account.add_transaction(value, when=when)
        # Result of `max_outflows` should bring balance to $0 if
        # applied as transactions:
        self.assertAlmostEqual(account.balance_at_time('end'),
                               Money(0),
                               places=4)

    def test_max_outflows_neg_to_pos(self, *args, **kwargs):
        """ Test max_outflows going from neg. to pos. balance """
        # Try with a negative starting balance and a positive ending
        # balance. With -$100 start and 200% interest compounding at
        # t=0.5, balance should be -$200 at t=0.5. Add $200 transaction
        # at t=0.5 so balance = 0 and another transaction at t='end' so
        # balance = $100.
        account = self.AccountType(self.owner,
                                   *args,
                                   balance=-200,
                                   rate=2.0,
                                   nper=2,
                                   **kwargs)
        account.add_transaction(100, when='start')
        account.add_transaction(200, when='0.5')
        account.add_transaction(100, when='end')
        result = account.max_outflows(self.timing)
        for when, value in result.items():
            account.add_transaction(value, when=when)
        # Result of `max_outflows` should bring balance to $0 if
        # applied as transactions:
        self.assertAlmostEqual(account.balance_at_time('end'),
                               Money(0),
                               places=4)

    def test_max_outflows_compound_disc(self, *args, **kwargs):
        """ Test max_outflows with discrete compounding """
        # Test compounding. First: discrete compounding, once at the
        # halfway point. Add a $100 transaction at when=0.5 just to be
        # sure.
        account = self.AccountType(self.owner,
                                   *args,
                                   balance=100,
                                   rate=1,
                                   nper=2,
                                   **kwargs)
        account.add_transaction(100, when=0.5)
        # Three evenly-weighted transactions for some extra complexity:
        timing = {Decimal(0): 1, Decimal(0.5): 1, Decimal(1): 1}
        result = account.max_outflows(timing)
        for when, value in result.items():
            account.add_transaction(value, when=when)
        # Result of `max_outflows` should bring balance to $0 if
        # applied as transactions:
        self.assertAlmostEqual(account.balance_at_time('end'),
                               Money(0),
                               places=4)

    def test_max_outflows_compound_cont(self, *args, **kwargs):
        """ Test max_outflows with continuous compounding. """
        # Now to test continuous compounding. Add a $100 transaction at
        # when=0.5 just to be sure.
        account = self.AccountType(self.owner,
                                   *args,
                                   balance=100,
                                   rate=1,
                                   nper='C',
                                   **kwargs)
        account.add_transaction(100, when='0.5')
        # Three evenly-weighted transactions, for extra complexity:
        timing = {Decimal(0): 1, Decimal(0.5): 1, Decimal(1): 1}
        result = account.max_outflows(timing)
        for when, value in result.items():
            account.add_transaction(value, when=when)
        # Result of `max_outflows` should bring balance to $0 if
        # applied as transactions:
        self.assertAlmostEqual(account.balance_at_time('end'),
                               Money(0),
                               places=4)

    def test_max_inflows_pos(self, *args, **kwargs):
        """ Test max_inflows with positive balance """
        # This method should always return Money('Infinity')
        account = self.AccountType(self.owner, *args, balance=100, **kwargs)
        result = account.max_inflows(self.timing)
        for value in result.values():
            self.assertEqual(value, Money('Infinity'))

    def test_max_inflows_neg(self, *args, **kwargs):
        """ Test max_inflows with negative balance """
        # This method should always return Money('Infinity')
        account = self.AccountType(self.owner, *args, balance=-100, **kwargs)
        result = account.max_inflows(self.timing)
        for value in result.values():
            self.assertEqual(value, Money('Infinity'))

    def test_min_outflows_pos(self, *args, **kwargs):
        """ Test Account.min_outflow with positive balance """
        # This method should always return $0
        account = self.AccountType(self.owner, *args, balance=100, **kwargs)
        result = account.min_outflows(self.timing)
        for value in result.values():
            self.assertAlmostEqual(value, Money(0), places=4)

    def test_min_outflows_neg(self, *args, **kwargs):
        """ Test min_outflow with negative balance """
        account = self.AccountType(self.owner, *args, balance=-100, **kwargs)
        result = account.min_outflows(self.timing)
        for value in result.values():
            self.assertAlmostEqual(value, Money(0), places=4)

    def test_min_inflows_pos(self, *args, **kwargs):
        """ Test min_inflow with positive balance """
        # This method should always return $0
        account = self.AccountType(self.owner, *args, balance=100, **kwargs)
        result = account.min_inflows(self.timing)
        for value in result.values():
            self.assertAlmostEqual(value, Money(0), places=4)

    def test_min_inflows_neg(self, *args, **kwargs):
        """ Test min_inflows with negative balance """
        account = self.AccountType(self.owner, *args, balance=-100, **kwargs)
        result = account.min_inflows(self.timing)
        for value in result.values():
            self.assertAlmostEqual(value, Money(0), places=4)

    def test_max_outflows_example(self, *args, **kwargs):
        """ Test max_outflows with its docstring example. """
        account = self.AccountType(self.owner,
                                   *args,
                                   balance=100,
                                   rate=1,
                                   nper=1,
                                   **kwargs)
        # This is taken straight from the docstring example:
        result = account.max_outflows({0: 1, 1: 1})
        target = {0: Money(-200) / 3, 1: Money(-200) / 3}
        self.assertEqual(result.keys(), target.keys())
        for timing in result:
            self.assertAlmostEqual(result[timing], target[timing], places=4)

    def test_taxable_income_gain(self, *args, **kwargs):
        """ Test Account.taxable_income with gains in account """
        # This method should return the growth in the account, which is
        # $200 at the start of the period. (The $100 withdrawal at the
        # end of the period doesn't affect taxable income.)
        account = self.AccountType(self.owner,
                                   *args,
                                   balance=100,
                                   rate=1.0,
                                   **kwargs)
        account.add_transaction(100, when='start')
        account.add_transaction(-100, when='end')
        self.assertEqual(account.taxable_income, Money(200))

    def test_taxable_income_loss(self, *args, **kwargs):
        """ Test Account.taxable_income with losses in account """
        # Losses are not taxable:
        account = self.AccountType(self.owner,
                                   *args,
                                   balance=-100,
                                   rate=1.0,
                                   **kwargs)
        account.add_transaction(100, when='start')
        account.add_transaction(-100, when='end')
        self.assertEqual(account.taxable_income, Money(0))

    def test_tax_withheld_pos(self, *args, **kwargs):
        """ Test Account.tax_withheld with positive balance. """
        # This method should always return $0
        account = self.AccountType(self.owner,
                                   *args,
                                   balance=100,
                                   rate=1.0,
                                   **kwargs)
        account.add_transaction(100, when='start')
        account.add_transaction(-100, when='end')
        self.assertEqual(account.tax_withheld, Money(0))

    def test_tax_withheld_neg(self, *args, **kwargs):
        """ Test Account.tax_withheld with negative balance. """
        account = self.AccountType(self.owner,
                                   *args,
                                   balance=-100,
                                   rate=1.0,
                                   **kwargs)
        account.add_transaction(100, when='start')
        account.add_transaction(-100, when='end')
        self.assertEqual(account.tax_withheld, Money(0))

    def test_tax_credit_pos(self, *args, **kwargs):
        """ Test Account.tax_credit with positive balance """
        # This method should always return $0, regardless of balance,
        # inflows, or outflows
        account = self.AccountType(self.owner,
                                   *args,
                                   balance=100,
                                   rate=1.0,
                                   **kwargs)
        account.add_transaction(100, when='start')
        account.add_transaction(-100, when='end')
        self.assertEqual(account.tax_credit, Money(0))

    def test_tax_credit_neg(self, *args, **kwargs):
        """ Test Account.tax_credit with negative balance """
        # Test with negative balance
        account = self.AccountType(self.owner,
                                   *args,
                                   balance=-100,
                                   rate=1.0,
                                   **kwargs)
        account.add_transaction(100, when='start')
        account.add_transaction(-100, when='end')
        self.assertEqual(account.tax_credit, Money(0))

    def test_tax_deduction_pos(self, *args, **kwargs):
        """ Test Account.tax_deduction with positive balance """
        # This method should always return $0, regardless of balance,
        # inflows, or outflows
        account = self.AccountType(self.owner,
                                   *args,
                                   balance=100,
                                   rate=1.0,
                                   **kwargs)
        account.add_transaction(100, when='start')
        account.add_transaction(-100, when='end')
        self.assertEqual(account.tax_deduction, Money(0))

    def test_tax_deduction_neg(self, *args, **kwargs):
        """ Test Account.tax_deduction with negative balance """
        # Test with negative balance
        account = self.AccountType(self.owner,
                                   *args,
                                   balance=-100,
                                   rate=1.0,
                                   **kwargs)
        account.add_transaction(100, when='start')
        account.add_transaction(-100, when='end')
        self.assertEqual(account.tax_deduction, Money(0))