Add all_positive checks in surface generator tests

Author: Onur R. Bingol

tests/test_surfgen.py

@@ -180,10 +180,24 @@ def test_bumps1(grid2):
     assert check
 
 
+def test_bumps1_all_positive_heights(grid2):
+    grid2.bumps(num_bumps=2, all_positive=True, bump_height=5, base_extent=2)
+    check_vals = grid2.grid()
+
+    check = False
+    for rows in check_vals:
+        for val in rows:
+            # should consider negative values too
+            if val[2] == 5.0:
+                check = True
+
+    assert check
+
+
 def test_bumps2(grid2):
     with pytest.raises(RuntimeError):
         # impossible to add 10 bumps on this specific grid
-        grid2.bumps(num_bumps=10, all_positive=True, bump_height=5, base_extent=2)
+        grid2.bumps(num_bumps=10, all_positive=False, bump_height=5, base_extent=2)
 
 
 def test_bumps3(gridw):