diff --git a/git_code_debt_server/metric_config.py b/git_code_debt_server/metric_config.py
index 7c7ed21..0995324 100644
--- a/git_code_debt_server/metric_config.py
+++ b/git_code_debt_server/metric_config.py
@@ -2,6 +2,7 @@
 import collections
 import re
 
+import staticconf.errors
 import staticconf.getters
 
 from git_code_debt_util.config import get_config_watcher
@@ -25,6 +26,11 @@ def contains(self, metric_name):
 
     @classmethod
     def from_yaml(cls, name, metrics, metric_expressions):
+        if not metrics and not metric_expressions:
+            raise staticconf.errors.ValidationError(
+                'Group {0} must define at least one of '
+                '`metrics` or `metric_expressions`'.format(name)
+            )
         return cls(
             name,
             set(metrics),
@@ -38,7 +44,11 @@ def _get_groups_from_yaml(yaml):
     # Here's an example yaml:
     # [{'Bar': {'metrics': ['Foo', 'Bar'], 'metric_expressions': ['^Baz']}}]
     return tuple(
-        Group.from_yaml(*group_dict.keys(), **group_dict.values()[0])
+        Group.from_yaml(
+            group_dict.keys()[0],
+            group_dict.values()[0].get('metrics', []),
+            group_dict.values()[0].get('metric_expressions', []),
+        )
         for group_dict in yaml
     )
 
diff --git a/metric_config.yaml b/metric_config.yaml
index 7b84dd2..1c6e39b 100644
--- a/metric_config.yaml
+++ b/metric_config.yaml
@@ -11,6 +11,7 @@
 #
 # This defines a group named Group1 which explicitly includes the metrics
 # FooMetric and BarMetric and also includes all metrics which match ^.*Baz.*$.
+# NOTE: metrics and metric_expressions may be omitted
 
 Groups:
     - Cheetah:
@@ -18,14 +19,11 @@ Groups:
         metric_expressions:
             - ^.*Cheetah.*$
     - Python:
-        metrics: []
         metric_expressions:
             - ^.*Python.*$
     - CurseWords:
-        metrics: []
         metric_expressions:
             - ^TotalCurseWords.*$
     - LinesOfCode:
-        metrics: []
         metric_expressions:
             - ^TotalLinesOfCode.*$
diff --git a/tests/git_code_debt_server/metric_config_test.py b/tests/git_code_debt_server/metric_config_test.py
index 98de7ab..3d8e0bb 100644
--- a/tests/git_code_debt_server/metric_config_test.py
+++ b/tests/git_code_debt_server/metric_config_test.py
@@ -2,79 +2,106 @@
 import mock
 import re
 
+import staticconf.errors
 import testify as T
 
 from git_code_debt_server.metric_config import _get_groups_from_yaml
 from git_code_debt_server.metric_config import Group
+from testing.base_classes.test import test
 
 
-class GroupTest(T.TestCase):
-    def test_from_yaml(self):
-        # Simulate a call we would get from yaml
-        group = Group.from_yaml('BazGroup', **{
-            'metrics': ['Foo', 'Bar'],
-            'metric_expressions': ['^.*Baz.*$'],
-        })
-
-        T.assert_equal(
-            group,
-            Group('BazGroup', set(['Foo', 'Bar']), (re.compile('^.*Baz.*$'),)),
-        )
-
-    def test_contains_does_not_contain(self):
-        group = Group('G', set(['Foo', 'Bar']), (re.compile('^.*Baz.*$'),))
-        T.assert_is(group.contains('buz'), False)
-
-    def test_contains_contains_by_name(self):
-        group = Group('G', set(['Foo', 'Bar']), (re.compile('^.*Baz.*$'),))
-        T.assert_is(group.contains('Foo'), True)
-
-    def test_contains_by_regex(self):
-        group = Group('G', set(['Foo', 'Bar']), (re.compile('^.*Baz.*$'),))
-        T.assert_is(group.contains('FooBaz'), True)
-
-
-class TestGetGroupsFromYaml(T.TestCase):
-    def test_get_groups_from_yaml(self):
-        # Grapped from sample run
-        groups_yaml = [
-            {'Cheetah': {
-                'metrics': [],
-                'metric_expressions': ['^.*Cheetah.*$'],
-            }},
-            {'Python': {
-                'metrics': [],
-                'metric_expressions': ['^.*Python.*$'],
-            }},
-            {'CurseWords': {
-                'metrics': [],
-                'metric_expressions': ['^TotalCurseWords.*$'],
-            }},
-            {'LinesOfCode': {
-                'metrics': [],
-                'metric_expressions': ['^TotalLinesOfCode.*$'],
-            }}
-        ]
-
-        groups = _get_groups_from_yaml(groups_yaml)
-        T.assert_equal(
-            groups,
-            (
-                # Regexes tested below
-                Group('Cheetah', set([]), (mock.ANY,)),
-                Group('Python', set([]), (mock.ANY,)),
-                Group('CurseWords', set([]), (mock.ANY,)),
-                Group('LinesOfCode', set([]), (mock.ANY,)),
-            ),
-        )
-
-        regexes = [group.metric_expressions[0].pattern for group in groups]
-        T.assert_equal(
-            regexes,
-            [
-                '^.*Cheetah.*$',
-                '^.*Python.*$',
-                '^TotalCurseWords.*$',
-                '^TotalLinesOfCode.*$',
-            ],
-        )
+@test
+def test_Group_from_yaml():
+    # Simulate a call we would get from yaml
+    group = Group.from_yaml('BazGroup', **{
+        'metrics': ['Foo', 'Bar'],
+        'metric_expressions': ['^.*Baz.*$'],
+    })
+
+    T.assert_equal(
+        group,
+        Group('BazGroup', set(['Foo', 'Bar']), (re.compile('^.*Baz.*$'),)),
+    )
+
+@test
+def test_Group_from_yaml_complains_if_nothing_useful_specified():
+    with T.assert_raises_exactly(
+        staticconf.errors.ValidationError,
+        'Group G1 must define at least one of `metrics` or `metric_expressions`'
+    ):
+        Group.from_yaml('G1', [], [])
+
+@test
+def test_Group_contains_does_not_contain():
+    group = Group('G', set(['Foo', 'Bar']), (re.compile('^.*Baz.*$'),))
+    T.assert_is(group.contains('buz'), False)
+
+@test
+def test_Group_contains_contains_by_name():
+    group = Group('G', set(['Foo', 'Bar']), (re.compile('^.*Baz.*$'),))
+    T.assert_is(group.contains('Foo'), True)
+
+@test
+def test_Group_contains_by_regex():
+    group = Group('G', set(['Foo', 'Bar']), (re.compile('^.*Baz.*$'),))
+    T.assert_is(group.contains('FooBaz'), True)
+
+
+@test
+def test_get_groups_from_yaml_smoke():
+    # Grapped from sample run
+    groups_yaml = [
+        {'Cheetah': {
+            'metrics': [],
+            'metric_expressions': ['^.*Cheetah.*$'],
+        }},
+        {'Python': {
+            'metrics': [],
+            'metric_expressions': ['^.*Python.*$'],
+        }},
+        {'CurseWords': {
+            'metrics': [],
+            'metric_expressions': ['^TotalCurseWords.*$'],
+        }},
+        {'LinesOfCode': {
+            'metrics': [],
+            'metric_expressions': ['^TotalLinesOfCode.*$'],
+        }}
+    ]
+
+    groups = _get_groups_from_yaml(groups_yaml)
+    T.assert_equal(
+        groups,
+        (
+            # Regexes tested below
+            Group('Cheetah', set([]), (mock.ANY,)),
+            Group('Python', set([]), (mock.ANY,)),
+            Group('CurseWords', set([]), (mock.ANY,)),
+            Group('LinesOfCode', set([]), (mock.ANY,)),
+        ),
+    )
+
+    regexes = [group.metric_expressions[0].pattern for group in groups]
+    T.assert_equal(
+        regexes,
+        [
+            '^.*Cheetah.*$',
+            '^.*Python.*$',
+            '^TotalCurseWords.*$',
+            '^TotalLinesOfCode.*$',
+        ],
+    )
+
+@test
+def test_get_groups_from_yaml_no_metrics_provided():
+    groups_yaml = [{'G1': {'metric_expressions': ['^Foo.*$']}}]
+    groups = _get_groups_from_yaml(groups_yaml)
+    # Regex tested below
+    T.assert_equal(groups, (Group('G1', set([]), (mock.ANY,)),))
+    T.assert_equal(groups[0].metric_expressions[0].pattern, '^Foo.*$')
+
+@test
+def test_get_groups_from_yaml_no_metric_expressions_provided():
+    groups_yaml = [{'G1': {'metrics': ['Foo']}}]
+    groups = _get_groups_from_yaml(groups_yaml)
+    T.assert_equal(groups, (Group('G1', set(['Foo']), tuple()),))