test(plot): check also matplotlib show=True

Author: ankostis

graphkit/network.py

@@ -496,6 +496,7 @@ def plot_graph(graph, filename=None, show=False, steps=None,
         call :func:`network.supported_plot_formats()` for more.
     :param boolean show:
         If it evaluates to true, opens the  diagram in a  matplotlib window.
+        If it equals ``-1``, it plots but does not open the Window.
     :param steps:
         a list of nodes & instructions to overlay on the diagram
     :param inputs:
@@ -616,6 +617,7 @@ def get_node_name(a):
         sio = io.BytesIO(png)
         img = mpimg.imread(sio)
         plt.imshow(img, aspect="equal")
-        plt.show()
+        if show != -1:
+            plt.show()
 
     return g

setup.py

@@ -35,7 +35,11 @@
      extras_require={
           'plot': ['pydot', 'matplotlib']
      },
-     tests_require=['numpy'],
+     tests_require=[
+          "numpy",
+          "pydot",       # to test plot
+          "matplotlib"   # to test plot
+     ],
      license='Apache-2.0',
      keywords=['graph', 'computation graph', 'DAG', 'directed acyclical graph'],
      classifiers=[

test/test_graphkit.py

@@ -138,6 +138,16 @@ def test_plotting():
     finally:
         shutil.rmtree(tdir, ignore_errors=True)
 
+    ## Don't open matplotlib window.
+    #
+    if sys.version_info < (3, 5):
+        # On PY< 3.5 it fails with:
+        #   nose.proxy.TclError: no display name and no $DISPLAY environment variable
+        # eg https://travis-ci.org/ankostis/graphkit/jobs/593957996
+        import matplotlib
+        matplotlib.use("Agg") 
+    pipeline.plot(show=-1)
+
     try:
         pipeline.plot('bad.format')
         assert False, "Should had failed writting arbitrary file format!"