tests: add neg integer test (#641)

Author: henryiii

docs/CHANGELOG.md

@@ -7,6 +7,7 @@
 #### User changes
 * Python 3.10 officially supported, with wheels.
 * Support subtraction on histograms [#636][]
+* Integer histograms are now signed [#636][]
 
 #### Bug fixes
 * Support custom setters on AxesTuple subclasses. [#627][]

tests/conftest.py

@@ -43,3 +43,16 @@ def metadata(request):
 )
 def count_storage(request):
     return request.param
+
+
+@pytest.fixture(
+    params=(
+        bh.storage.Double,
+        bh.storage.Int64,
+        bh.storage.AtomicInt64,
+        bh.storage.Unlimited,
+    ),
+    ids=("Double", "Int64", "AtomicInt64", "Unlimited"),
+)
+def count_single_storage(request):
+    return request.param

tests/test_histogram.py

@@ -152,12 +152,8 @@ def test_fill_1d(flow):
         assert get(h, bh.overflow) == 1
 
 
-@pytest.mark.parametrize(
-    "storage",
-    [bh.storage.Int64, bh.storage.Double, bh.storage.Unlimited, bh.storage.AtomicInt64],
-)
-def test_setting(storage):
-    h = bh.Histogram(bh.axis.Regular(10, 0, 1), storage=storage())
+def test_setting(count_single_storage):
+    h = bh.Histogram(bh.axis.Regular(10, 0, 1), storage=count_single_storage())
     h[bh.underflow] = 1
     h[0] = 2
     h[1] = 3
@@ -1284,3 +1280,12 @@ def test_sum_empty_axis():
     )
     assert hist.sum().value == 0
     assert "Str" in repr(hist)
+
+
+# Issue 618
+def test_negative_fill(count_storage):
+    h = bh.Histogram(bh.axis.Integer(0, 3), storage=count_storage())
+    h.fill(1, weight=-1)
+
+    answer = np.array([0, -1, 0])
+    assert h.values() == approx(answer)