correct test for shape errors

This test was previously incorrect, but because we didn't actually
check the number of orbitals on constant values on finalization
this was not caught.

kwant/tests/test_system.py

@@ -75,19 +75,15 @@ def test_hamiltonian_submatrix(vectorize):
     raises(ValueError, kwant.solvers.default.greens_function, syst3, 0.2)
 
     # Test for shape errors.
-    syst[chain2(0), chain(2)] = np.array([[1, 2]])
-    syst2 = syst.finalized()
-    raises(ValueError, syst2.hamiltonian_submatrix)
-    raises(ValueError, syst2.hamiltonian_submatrix, sparse=True)
-    syst[chain2(0), chain(2)] = 1
-    syst2 = syst.finalized()
-    raises(ValueError, syst2.hamiltonian_submatrix)
-    raises(ValueError, syst2.hamiltonian_submatrix, sparse=True)
-    if vectorize:  # non-vectorized systems don't check this at finalization
-        # Add another hopping of the same type but with a different
-        # (and still incompatible) shape.
-        syst[chain2(0), chain(1)] = np.array([[1, 2]])
-        raises(ValueError, syst.finalized)
+    for onsite in ([[1, 2]], 1):
+        syst[chain2(0), chain(2)] = onsite
+        if vectorize:
+            # non-vectorized systems don't check this at finalization
+            raises(ValueError, syst.finalized)
+        else:
+            syst2 = syst.finalized()
+            raises(ValueError, syst2.hamiltonian_submatrix)
+            raises(ValueError, syst2.hamiltonian_submatrix, sparse=True)
 
 
 @pytest.mark.parametrize("vectorize", [False, True])