Fix Python unit test.

test/python_unit/geometric_shapes.py

@@ -157,11 +157,21 @@ class TestGeometricShapes(TestCase):
         convex = hppfcl.Convex(verts, faces)
 
         verts.append (np.array([0, 0, 1]))
-        convexHull = hppfcl.Convex.convexHull(verts, False, None)
-        convexHull = hppfcl.Convex.convexHull(verts, False, "")
+        try:
+            convexHull = hppfcl.Convex.convexHull(verts, False, None)
+            qhullAvailable = True
+        except Exception as e:
+            self.assertEqual(str(e), "Library built without qhull. Cannot build object of this type.")
+            qhullAvailable = False
 
-        convexHull = hppfcl.Convex.convexHull(verts, True, "")
+        if qhullAvailable:
+            convexHull = hppfcl.Convex.convexHull(verts, False, "")
+            convexHull = hppfcl.Convex.convexHull(verts, True, "")
 
+            try:
+                convexHull = hppfcl.Convex.convexHull(verts[:3], False, None)
+            except Exception as e:
+                self.assertIn(str(e), "You shouldn't use this function with less than 4 points.")
 
 if __name__ == '__main__':
     unittest.main()