make external_graph_libs tests optional (only run if ext lib is installed)

networkx shouldn't be a dependency of rdflib just to run tests. Also
graph_tool heavily depends on C libs and can't easily be installed via pip
(or via apt-get on travis).
Hence, the doctests are duplicated into proper tests that auto skip if
networkx or graph_tool can't be imported.

3 files changed, 98 insertions, 4 deletions

diff --git a/rdflib/extras/external_graph_libs.py b/rdflib/extras/external_graph_libs.py
index 8423f4a0..10daf949 100644
--- a/rdflib/extras/external_graph_libs.py
+++ b/rdflib/extras/external_graph_libs.py
@@ -10,6 +10,10 @@ from __future__ import unicode_literals
 Currently the following libraries are supported:
 - networkx: MultiDiGraph, DiGraph, Graph
 - graph_tool: Graph
+
+Doctests in this file are all skipped, as we can't run them conditionally if
+networkx or graph_tool are available and they would err otherwise.
+see ../../test/test_extras_external_graph_libs.py for conditional tests
 """
 
 import logging
@@ -333,13 +337,10 @@ def rdflib_to_graphtool(
     return g
 
 
-def main(): # pragma: no cover
+if __name__ == '__main__':
     import sys
     import logging.config
     logging.basicConfig(level=logging.DEBUG)
 
     import nose
     nose.run(argv=[sys.argv[0], sys.argv[0], '-v', '--with-doctest'])
-
-if __name__ == '__main__':
-    main()
diff --git a/setup.cfg b/setup.cfg
index a4e33487..74635d08 100644
--- a/setup.cfg
+++ b/setup.cfg
@@ -4,3 +4,4 @@ attr=!known_issue,!non_core,!performancetest
 verbosity=1
 with-doctest=1
 exclude=rdflib.plugins.sparql.paths
+exclude=rdflib.extras.external_graph_libs
diff --git a/test/test_extras_external_graph_libs.py b/test/test_extras_external_graph_libs.py
new file mode 100644
index 00000000..2986d258
--- /dev/null
+++ b/test/test_extras_external_graph_libs.py
@@ -0,0 +1,92 @@
+from nose import SkipTest
+from rdflib import Graph, URIRef, Literal
+
+def test_rdflib_to_networkx():
+    try:
+        import networkx
+    except ImportError:
+        raise SkipTest("couldn't find networkx")
+    from rdflib.extras.external_graph_libs import rdflib_to_networkx_multidigraph
+    from rdflib.extras.external_graph_libs import rdflib_to_networkx_digraph
+    from rdflib.extras.external_graph_libs import rdflib_to_networkx_graph
+    g = Graph()
+    a, b, l = URIRef('a'), URIRef('b'), Literal('l')
+    p, q = URIRef('p'), URIRef('q')
+    edges = [(a, p, b), (a, q, b), (b, p, a), (b, p, l)]
+    for t in edges:
+        g.add(t)
+
+
+    mdg = rdflib_to_networkx_multidigraph(g)
+    assert len(mdg.edges()) == 4
+    assert mdg.has_edge(a, b)
+    assert mdg.has_edge(a, b, key=p)
+    assert mdg.has_edge(a, b, key=q)
+
+    mdg = rdflib_to_networkx_multidigraph(g, edge_attrs=lambda s, p, o: {})
+    assert mdg.has_edge(a, b, key=0)
+    assert mdg.has_edge(a, b, key=1)
+
+
+    dg = rdflib_to_networkx_digraph(g)
+    assert dg[a][b]['weight'] == 2
+    assert sorted(dg[a][b]['triples']) == [(a, p, b), (a, q, b)]
+    assert len(dg.edges()) == 3
+    assert dg.size() == 3
+    assert dg.size(weight='weight') == 4.0
+
+    dg = rdflib_to_networkx_graph(g, False, edge_attrs=lambda s, p, o:{})
+    assert 'weight' not in dg[a][b]
+    assert 'triples' not in dg[a][b]
+
+
+    ug = rdflib_to_networkx_graph(g)
+    assert ug[a][b]['weight'] == 3
+    assert sorted(ug[a][b]['triples']) == [(a, p, b), (a, q, b), (b, p, a)]
+    assert len(ug.edges()) == 2
+    assert ug.size() == 2
+    assert ug.size(weight='weight') == 4.0
+
+    ug = rdflib_to_networkx_graph(g, False, edge_attrs=lambda s, p, o:{})
+    assert 'weight' not in ug[a][b]
+    assert 'triples' not in ug[a][b]
+
+
+def test_rdflib_to_graphtool():
+    try:
+        from graph_tool import util as gt_util
+    except ImportError:
+        raise SkipTest("couldn't find graph_tool")
+    from rdflib.extras.external_graph_libs import rdflib_to_graphtool
+    g = Graph()
+    a, b, l = URIRef('a'), URIRef('b'), Literal('l')
+    p, q = URIRef('p'), URIRef('q')
+    edges = [(a, p, b), (a, q, b), (b, p, a), (b, p, l)]
+    for t in edges:
+        g.add(t)
+
+    mdg = rdflib_to_graphtool(g)
+    assert len(list(mdg.edges())) == 4
+
+    vpterm = mdg.vertex_properties['term']
+    va = gt_util.find_vertex(mdg, vpterm, a)[0]
+    vb = gt_util.find_vertex(mdg, vpterm, b)[0]
+    vl = gt_util.find_vertex(mdg, vpterm, l)[0]
+    assert (va, vb) in [(e.source(), e.target()) for e in list(mdg.edges())]
+
+    epterm = mdg.edge_properties['term']
+    assert len(list(gt_util.find_edge(mdg, epterm, p))) == 3
+    assert len(list(gt_util.find_edge(mdg, epterm, q))) == 1
+
+    mdg = rdflib_to_graphtool(
+        g,
+        e_prop_names=[str('name')],
+        transform_p=lambda s, p, o: {str('name'): unicode(p)})
+    epterm = mdg.edge_properties['name']
+    assert len(list(gt_util.find_edge(mdg, epterm, unicode(p)))) == 3
+    assert len(list(gt_util.find_edge(mdg, epterm, unicode(q)))) == 1
+
+if __name__ == "__main__":
+    import sys
+    import nose
+    nose.main(defaultTest=sys.argv[0])