diff --git a/tests/test_math.py b/tests/test_math.py
new file mode 100644
index 0000000..5a75858
--- /dev/null
+++ b/tests/test_math.py
@@ -0,0 +1,32 @@
+import numpy
+from wally.statistic import rebin_histogram
+
+
+def array_eq(x: numpy.array, y: numpy.array, max_diff: float = 1E-3) -> bool:
+    return numpy.abs(x - y).max() <= max_diff
+
+
+def test_rebin_histo():
+    curr_histo = numpy.empty((100,), dtype=int)
+    curr_histo[:] = 1
+    edges = numpy.arange(100)
+    new_histo, new_edges = rebin_histogram(curr_histo, edges, 10)
+
+    assert new_edges.shape == (10,)
+    assert new_histo.shape == (10,)
+    assert new_edges.dtype.name.startswith('float')
+    assert new_histo.dtype.name.startswith('int')
+
+    assert array_eq(new_edges, numpy.arange(10) * 9.9)
+    assert new_histo.sum() == curr_histo.sum()
+    assert list(new_histo) == [10] * 10
+
+    new_histo, new_edges = rebin_histogram(curr_histo, edges, 3,
+                                           left_tail_idx=20,
+                                           right_tail_idx=50)
+
+    assert new_edges.shape == (3,)
+    assert new_histo.shape == (3,)
+    assert array_eq(new_edges, numpy.array([20, 30, 40]))
+    assert new_histo.sum() == curr_histo.sum()
+    assert list(new_histo) == [30, 10, 60]