diff --git a/tests/mathutil/test_bounding_plane.py b/tests/mathutil/test_bounding_plane.py
new file mode 100644
index 0000000000..eeb9b2b11e
--- /dev/null
+++ b/tests/mathutil/test_bounding_plane.py
@@ -0,0 +1,64 @@
+from panda3d.core import Plane, BoundingPlane, BoundingSphere, BoundingVolume
+
+
+def test_plane_contains_sphere():
+    plane = BoundingPlane((0, 0, 1, 0))
+
+    # Sphere above plane
+    assert plane.contains(BoundingSphere((0, 0, 2), 1)) == BoundingVolume.IF_no_intersection
+
+    # Sphere intersecting surface of plane
+    assert plane.contains(BoundingSphere((0, 0, 0), 1)) == BoundingVolume.IF_possible | BoundingVolume.IF_some
+
+    # Sphere below plane
+    assert plane.contains(BoundingSphere((0, 0, -2), 1)) == BoundingVolume.IF_possible | BoundingVolume.IF_some | BoundingVolume.IF_all
+
+
+def test_plane_contains_plane():
+    # Plane should always fully contain itself.
+    a = BoundingPlane((1, 0, 0, 1))
+    assert a.contains(a) == BoundingVolume.IF_possible | BoundingVolume.IF_some | BoundingVolume.IF_all
+
+    # Plane with its mirror image
+    a = BoundingPlane((1, 0, 0, 1))
+    b = BoundingPlane((-1, 0, 0, -1))
+    assert a.contains(b) == BoundingVolume.IF_no_intersection
+    assert b.contains(a) == BoundingVolume.IF_no_intersection
+
+    # One plane above the other
+    a = BoundingPlane(Plane((1, 0, 0), (1, 0, 0)))
+    b = BoundingPlane(Plane((1, 0, 0), (2, 0, 0)))
+    assert a.contains(b) == BoundingVolume.IF_possible | BoundingVolume.IF_some
+    assert b.contains(a) == BoundingVolume.IF_possible | BoundingVolume.IF_some | BoundingVolume.IF_all
+
+    # Opposing planes with distance between them.
+    a = BoundingPlane(Plane((1, 0, 0), (1, 0, 0)))
+    b = BoundingPlane(Plane((-1, 0, 0), (2, 0, 0)))
+    assert a.contains(b) == BoundingVolume.IF_no_intersection
+    assert b.contains(a) == BoundingVolume.IF_no_intersection
+
+    # Planes overlapping in the same axis.
+    a = BoundingPlane(Plane((1, 0, 0), (2, 0, 0)))
+    b = BoundingPlane(Plane((-1, 0, 0), (1, 0, 0)))
+    assert a.contains(b) == BoundingVolume.IF_possible | BoundingVolume.IF_some
+    assert b.contains(a) == BoundingVolume.IF_possible | BoundingVolume.IF_some
+
+    # Planes overlapping due to not sharing a normal vector.
+    a = BoundingPlane(Plane((1, 0, 0), (2, 0, 0)))
+    b = BoundingPlane(Plane((0.8, 0.6, 0), (4, 0, 0)))
+    assert a.contains(b) == BoundingVolume.IF_possible | BoundingVolume.IF_some
+    assert b.contains(a) == BoundingVolume.IF_possible | BoundingVolume.IF_some
+
+    # Same as above.
+    a = BoundingPlane(Plane((1, 0, 0), (2, 0, 0)))
+    b = BoundingPlane(Plane((-0.8, -0.6, 0), (4, 0, 0)))
+    assert a.contains(b) == BoundingVolume.IF_possible | BoundingVolume.IF_some
+    assert b.contains(a) == BoundingVolume.IF_possible | BoundingVolume.IF_some
+
+    # Planes pointing along different major axes.
+    a = BoundingPlane(Plane((1, 0, 0, 0)))
+    b = BoundingPlane(Plane((0, 1, 0, 0)))
+    c = BoundingPlane(Plane((0, 0, 1, 0)))
+    assert a.contains(b) == BoundingVolume.IF_possible | BoundingVolume.IF_some
+    assert b.contains(c) == BoundingVolume.IF_possible | BoundingVolume.IF_some
+    assert a.contains(c) == BoundingVolume.IF_possible | BoundingVolume.IF_some