add test checking that js deps are present

- which should make debugging somewhat less painful

Author: etpinard

plotly/tests/test_optional/test_jupyter/test_jupyter.py

@@ -12,10 +12,17 @@
 import subprocess
 
 PATH_ROOT = path.dirname(__file__)
+PATH_NODE_MODULES = path.join(PATH_ROOT, 'node_modules')
 PATH_FIXTURES = path.join(PATH_ROOT, 'fixtures')
 PATH_JS_TESTS = path.join(PATH_ROOT, 'js_tests')
 
 
+class PlotlyJupyterTestDeps(TestCase):
+
+    def test_node_modules(self):
+        self.assertTrue(path.isdir(PATH_NODE_MODULES))
+
+
 class Common(TestCase):
     __test__ = False
     name = None