diff --git a/tests/test_reports_balance.py b/tests/test_reports_balance.py
index 07e238662870c712fc76a39a84f210ac8aa691c1..7913156940639c97d059d69c585b24c8fbfa7d4d 100644
--- a/tests/test_reports_balance.py
+++ b/tests/test_reports_balance.py
@@ -24,6 +24,14 @@ from . import testutil
 
 from conservancy_beancount.reports import core
 
+DEFAULT_STRINGS = [
+    ({}, "Zero balance"),
+    ({'JPY': 0, 'BRL': 0}, "Zero balance"),
+    ({'USD': '20.00'}, "20.00 USD"),
+    ({'EUR': '50.00', 'GBP': '80.00'}, "80.00 GBP, 50.00 EUR"),
+    ({'JPY': '-5500.00', 'BRL': '-8500.00'}, "-8,500.00 BRL, -5,500 JPY"),
+]
+
 def test_empty_balance():
     balance = core.Balance()
     assert not balance
@@ -150,13 +158,44 @@ def test_eq(kwargs1, kwargs2, expected):
     actual = bal1 == bal2
     assert actual == expected
 
-@pytest.mark.parametrize('balance_map_kwargs,expected', [
-    ({}, "Zero balance"),
-    ({'JPY': 0, 'BRL': 0}, "Zero balance"),
-    ({'USD': '20.00'}, "20.00 USD"),
-    ({'EUR': '50.00', 'GBP': '80.00'}, "80.00 GBP, 50.00 EUR"),
-    ({'JPY': '-55.00', 'BRL': '-85.00'}, "-85.00 BRL, -55.00 JPY"),
-])
+@pytest.mark.parametrize('balance_map_kwargs,expected', DEFAULT_STRINGS)
 def test_str(balance_map_kwargs, expected):
     amounts = testutil.balance_map(**balance_map_kwargs)
     assert str(core.Balance(amounts.items())) == expected
+
+@pytest.mark.parametrize('bal_kwargs,expected', DEFAULT_STRINGS)
+def test_format_defaults(bal_kwargs, expected):
+    amounts = testutil.balance_map(**bal_kwargs)
+    assert core.Balance(amounts).format() == expected
+
+@pytest.mark.parametrize('fmt,expected', [
+    ('¤##0.0', '¥5000, -€1500.00'),
+    ('#,#00.0¤¤', '5,000JPY, -1,500.00EUR'),
+    ('¤+##0.0;¤-##0.0', '¥+5000, €-1500.00'),
+    ('#,#00.0 ¤¤;(#,#00.0 ¤¤)', '5,000 JPY, (1,500.00 EUR)'),
+])
+def test_format_fmt(fmt, expected):
+    amounts = testutil.balance_map(JPY=5000, EUR=-1500)
+    balance = core.Balance(amounts)
+    assert balance.format(fmt) == expected
+
+@pytest.mark.parametrize('sep', [
+    '; ',
+    '—',
+    '\0',
+])
+def test_format_sep(sep):
+    bal_kwargs, expected = DEFAULT_STRINGS[-1]
+    expected = expected.replace(', ', sep)
+    amounts = testutil.balance_map(**bal_kwargs)
+    balance = core.Balance(amounts)
+    assert balance.format(sep=sep) == expected
+
+@pytest.mark.parametrize('empty', [
+    "N/A",
+    "Zero",
+    "ø",
+])
+def test_format_empty(empty):
+    balance = core.Balance()
+    assert balance.format(empty=empty) == empty