Trac #12364: ValueError + AttributeError when calling layout_graphviz…

… on a Hasse diagram

With sage-4.7.2 and {{{sage -i dot2tex}}} installed :

{{{
sage: m = WordMorphism('a->abb,b->ba')
sage: w = m.fixed_point('a')
sage: prefix = Word(list(w[:100]))
sage: pals = prefix.palindromes()
sage: poset = Poset((pals, lambda x,y: x.is_factor(y)))
sage: H = poset.hasse_diagram()
sage: H.layout_graphviz()         #require dot2tex
ERROR    Failed to process input
Traceback (most recent call last):
...
ValueError: invalid literal for int() with base 10: '249.88'
-------------------------------------------------------
Traceback (most recent call last):
...
AttributeError: 'str' object has no attribute 'iteritems'
}}}

This came up in #12351.

URL: https://trac.sagemath.org/12364
Reported by: slabbe
Ticket author(s): Sébastien Labbé
Reviewer(s): Travis Scrimshaw

src/sage/graphs/generic_graph.py

@@ -17947,6 +17947,18 @@ def layout_graphviz(self, dim = 2, prog = 'dot', **options):
 
             Use the graphviz functionality of Networkx 1.0 once it
             will be merged into Sage.
+
+        TESTS:
+
+        Make sure that :trac:`12364` is fixed::
+
+            sage: m = WordMorphism('a->abb,b->ba')
+            sage: w = m.fixed_point('a')
+            sage: prefix = Word(list(w[:100]))
+            sage: pals = prefix.palindromes()
+            sage: poset = Poset((pals, lambda x,y: x.is_factor(y)))
+            sage: H = poset.hasse_diagram()
+            sage: d = H.layout_graphviz()     # optional - dot2tex graphviz
         """
         assert_have_dot2tex()
         assert dim == 2, "3D graphviz layout not implemented"