a few more fixes for various doctests

src/sage/graphs/base/dense_graph.pyx

@@ -487,6 +487,10 @@ def _test_adjacency_sequence_out():
     high = 500
     randg = DiGraph(GraphGenerators().RandomGNP(randint(low, high), random()))
     n = randg.order()
+    while n <= 1:
+        randg = DiGraph(GraphGenerators().RandomGNP(randint(low, high), random()))
+        n = randg.order()
+
     cdef DenseGraph g = DenseGraph(n,
                                    verts=randg.vertex_iterator(),
                                    arcs=randg.edge_iterator(labels=False))

src/sage/graphs/digraph.py

@@ -1576,6 +1576,8 @@ def feedback_edge_set(self, constraint_generation=True, value_only=False, solver
         `vu` is in the returned feedback arc set::
 
            sage: g = graphs.RandomGNP(5,.3)
+           sage: while not g.num_edges():
+           ....:     g = graphs.RandomGNP(5,.3)
            sage: dg = DiGraph(g)
            sage: feedback = dg.feedback_edge_set()
            sage: u,v,l = next(g.edge_iterator())

src/sage/rings/number_field/number_field_ideal.py

@@ -2196,8 +2196,13 @@ def invertible_residues(self, reduce=True):
         Check that the integrality is not lost,  cf. :trac:`30801`::
 
             sage: K.<a> = NumberField(x^2 + x + 1)
-            sage: list(K.ideal(8).invertible_residues())[:5]
-            [1, a - 1, -3*a, -2*a + 3, -a - 1]
+            sage: for k in K.ideal(8).invertible_residues():
+            ....:     assert k.is_unit() and k.is_integral()
+            sage: some_residues = list(K.ideal(8).invertible_residues())[:5]
+            sage: one = [1, a - 1, -3*a, -2*a + 3, -a - 1]
+            sage: other = [1, a + 2, 3*a + 3, -2*a + 3, a]
+            sage: some_residues in (one, other)
+            True
 
         AUTHOR: John Cremona
         """