TST: fix error in test assertion.

Author: phmbressan

tests/test_tank.py

@@ -191,7 +191,9 @@ def test_mass_based_tank():
 
     # Assert volume bounds
     assert (real_tank_lox.gas_height <= real_tank_lox.geometry.top).all
-    assert (example_tank_lox.gas_height <= example_tank_lox.geometry.total_volume).all
+    assert (real_tank_lox.fluid_volume <= real_tank_lox.geometry.total_volume).all
+    assert (example_tank_lox.gas_height <= example_tank_lox.geometry.top).all
+    assert (example_tank_lox.fluid_volume <= example_tank_lox.geometry.total_volume).all
 
     initial_liquid_mass = 5
     initial_gas_mass = 0