Add tests for BenchmarkResult serialization, percentile handling, and

ScenarioGroup addition behavior

Author: Евгений Блинов

tests/units/test_benchmark_result.py

@@ -40,11 +40,12 @@ def test_mean_computed_correctly(self) -> None:
         assert result.mean == expected
 
     def test_mean_uses_fsum_precision(self) -> None:
-        # floating point: sum of many small numbers may differ from fsum
-        durations = tuple(0.1 for _ in range(10))
+        # fsum handles cancellation correctly; plain sum loses precision:
+        # sum([1e20, 1.0, -1e20]) == 0.0, fsum == 1.0
+        durations = (1e20, 1.0, -1e20)
         result = make_result(durations)
-        expected = math.fsum(durations) / len(durations)
-        assert result.mean == expected
+        assert result.mean == pytest.approx(1.0 / 3)
+        assert result.mean != sum(durations) / len(durations)
 
     def test_best_is_min(self) -> None:
         result = make_result((3.0, 1.0, 2.0))
@@ -114,6 +115,8 @@ def test_percentile_100_returns_all(self) -> None:
         result = make_result((1.0, 2.0, 3.0))
         trimmed = result.percentile(100)
         assert len(trimmed.durations) == 3
+        assert trimmed.is_primary is False
+        assert trimmed.durations == tuple(sorted(result.durations))
 
     def test_percentile_small_number(self) -> None:
         result = make_result((1.0, 2.0, 3.0))
@@ -213,6 +216,9 @@ def test_to_json_valid_json(self) -> None:
         result = make_result((0.1, 0.2))
         data = json.loads(result.to_json())
         assert isinstance(data, dict)
+        assert isinstance(data['durations'], list)
+        assert isinstance(data['is_primary'], bool)
+        assert 'scenario' in data
 
     def test_to_json_contains_durations(self) -> None:
         result = make_result((0.1, 0.2, 0.3))
@@ -312,6 +318,18 @@ def test_from_json_is_primary_not_bool_raises(self) -> None:
         with pytest.raises(ValueError, match='is_primary'):
             BenchmarkResult.from_json(payload)
 
+    def test_from_json_is_primary_int_raises(self) -> None:
+        # int 1 is not a bool even though bool is a subclass of int
+        payload = json.dumps({'durations': [0.1], 'is_primary': 1})
+        with pytest.raises(ValueError, match='is_primary'):
+            BenchmarkResult.from_json(payload)
+
+    def test_percentile_single_element(self) -> None:
+        result = make_result((5.0,))
+        trimmed = result.percentile(50)
+        assert trimmed.durations == (5.0,)
+        assert trimmed.is_primary is False
+
     def test_from_json_missing_is_primary_raises(self) -> None:
         payload = json.dumps({'durations': [0.1, 0.2]})
         with pytest.raises(ValueError, match='required fields'):

tests/units/test_scenario.py

@@ -209,7 +209,7 @@ def test_run_result_is_primary(self) -> None:
 
     def test_run_args_incompatible_raises_type_error(self) -> None:
         s = Scenario(lambda: None, args=[1, 2], name='s', number=1)
-        with pytest.raises(TypeError):
+        with pytest.raises(TypeError, match='argument'):
             s.run()
 
     def test_run_exception_mid_iteration(self) -> None:
@@ -249,6 +249,9 @@ def test_radd_group_scenario(self) -> None:
         s1 = Scenario(lambda: None, name='s1')
         s2 = Scenario(lambda: None, name='s2')
         g = ScenarioGroup(s1)
-        # g + s2 is g.__add__(s2), but we also want s2.__radd__(g) to work
+        # s2.__radd__(g) = ScenarioGroup(*g._scenarios, s2) = [s1, s2]
         group = s2.__radd__(g)
         assert isinstance(group, ScenarioGroup)
+        results = group.run()
+        assert results[0].scenario is s1
+        assert results[1].scenario is s2