diff --git a/tests/test_data_posting.py b/tests/test_data_posting.py
index b9ee686cf755e80fed4dd72d0ce161ac316428ac..5f6dc05b18547dc793e86020bf4c889aca37a74f 100644
--- a/tests/test_data_posting.py
+++ b/tests/test_data_posting.py
@@ -39,25 +39,64 @@ NON_PAYMENT_ACCOUNTS = {
     'UnearnedIncome:MatchPledges',
 }
 
+AMOUNTS = [
+    None,
+    '-25.50',
+    0,
+    '25.75',
+]
+
 def Posting(account, number,
             currency='USD', cost=None, price=None, flag=None,
             **meta):
     if not meta:
         meta = None
+    if number is not None:
+        number = Decimal(number)
     return data.Posting(
         data.Account(account),
-        bc_amount.Amount(Decimal(number), currency),
+        bc_amount.Amount(number, currency),
         cost,
         price,
         flag,
         meta,
     )
 
-def check_all_thresholds(post, threshold, expected):
-    assert post.is_payment(threshold) is expected
-    assert post.is_payment(-threshold) is expected
-    assert post.is_payment(Decimal(threshold)) is expected
-    assert post.is_payment(Decimal(-threshold)) is expected
+def check_all_thresholds(expected, method, threshold, *args):
+    assert method(threshold, *args) is expected
+    assert method(Decimal(threshold), *args) is expected
+
+@pytest.mark.parametrize('amount', AMOUNTS)
+def test_is_credit(amount):
+    expected = None if amount is None else float(amount) > 0
+    assert Posting('Assets:Cash', amount).is_credit() is expected
+
+def test_is_credit_threshold():
+    post = Posting('Assets:Cash', 25)
+    check_all_thresholds(True, post.is_credit, 0)
+    check_all_thresholds(True, post.is_credit, 20)
+    check_all_thresholds(False, post.is_credit, 40)
+
+def test_is_credit_default():
+    post = Posting('Assets:Cash', None)
+    assert post.is_credit(default=True) is True
+    assert post.is_credit(default=False) is False
+
+@pytest.mark.parametrize('amount', AMOUNTS)
+def test_is_debit(amount):
+    expected = None if amount is None else float(amount) < 0
+    assert Posting('Assets:Cash', amount).is_debit() is expected
+
+def test_is_debit_threshold():
+    post = Posting('Assets:Cash', -25)
+    check_all_thresholds(True, post.is_debit, 0)
+    check_all_thresholds(True, post.is_debit, 20)
+    check_all_thresholds(False, post.is_debit, 40)
+
+def test_is_debit_default():
+    post = Posting('Assets:Cash', None)
+    assert post.is_debit(default=True) is True
+    assert post.is_debit(default=False) is False
 
 @pytest.mark.parametrize('acct', PAYMENT_ACCOUNTS)
 def test_is_payment(acct):
@@ -71,24 +110,24 @@ def test_is_payment(acct):
 def test_is_not_payment_account(acct, amount, threshold):
     post = Posting(acct, -amount)
     assert not post.is_payment()
-    check_all_thresholds(post, threshold, False)
+    check_all_thresholds(False, post.is_payment, threshold)
 
 @pytest.mark.parametrize('acct', PAYMENT_ACCOUNTS)
 def test_is_payment_with_threshold(acct):
     threshold = len(acct) * 10
     post = Posting(acct, -500)
-    check_all_thresholds(post, threshold, True)
+    check_all_thresholds(True, post.is_payment, threshold)
 
 @pytest.mark.parametrize('acct', PAYMENT_ACCOUNTS)
 def test_is_not_payment_by_threshold(acct):
     threshold = len(acct) * 10
     post = Posting(acct, -9)
-    check_all_thresholds(post, threshold, False)
+    check_all_thresholds(False, post.is_payment, threshold)
 
 @pytest.mark.parametrize('acct', PAYMENT_ACCOUNTS)
 def test_is_not_payment_but_credit(acct):
     post = Posting(acct, 9)
     assert not post.is_payment()
-    check_all_thresholds(post, 0, False)
-    check_all_thresholds(post, 5, False)
-    check_all_thresholds(post, 10, False)
+    check_all_thresholds(False, post.is_payment, 0)
+    check_all_thresholds(False, post.is_payment, 5)
+    check_all_thresholds(False, post.is_payment, 10)