trappy: allow running the testsuite in environments without ipython

nose tries to import all __init__.py files.  Even if you do in
trappy/__init__.py:

try:
    import trappy.nbexport
except ImportError:
    pass

The testsuite fails because it then goes on and tries to import
trappy/nbexport/__init__.py.  To avoid that, let
trappy/nbexport/__init__.py fail gracefully if it fails to import
anything needing for the export.

2 files changed, 15 insertions, 10 deletions

diff --git a/trappy/nbexport/__init__.py b/trappy/nbexport/__init__.py
index 0293318..050a357 100644
--- a/trappy/nbexport/__init__.py
+++ b/trappy/nbexport/__init__.py
@@ -17,13 +17,9 @@
 * Custom Preprocessing
 """
 
-from nbconvert.exporters.html import HTMLExporter
-from trappy.nbexport.preprocessors import TrappyPlotterPreprocessor
-
-
-class HTML(HTMLExporter):
-    """HTML Exporter class for TRAPpy notebooks"""
-
-    def __init__(self, **kwargs):
-        super(HTML, self).__init__(**kwargs)
-        self.register_preprocessor(TrappyPlotterPreprocessor, enabled=True)
+try:
+    from trappy.nbexport.exporter import HTML
+except ImportError:
+    # Avoid testsuite errors when the testsuite is run in an environment without
+    # ipython
+    HTML = object
diff --git a/trappy/nbexport/preprocessors.py b/trappy/nbexport/exporter.py
index 096dab6..d83ca96 100644
--- a/trappy/nbexport/preprocessors.py
+++ b/trappy/nbexport/exporter.py
@@ -16,6 +16,7 @@
 """Preprocessor to remove Marked Lines from IPython Output Cells"""
 
 
+from nbconvert.exporters.html import HTMLExporter
 from nbconvert.preprocessors import Preprocessor
 import os
 import re
@@ -27,6 +28,14 @@ IMPORT_SCRIPT = r'/\* TRAPPY_PUBLISH_IMPORT = "([^"]+)" \*/'
 SOURCE_LIB = r'<!-- TRAPPY_PUBLISH_SOURCE_LIB = "([^"]+)" -->'
 
 
+class HTML(HTMLExporter):
+    """HTML Exporter class for TRAPpy notebooks"""
+
+    def __init__(self, **kwargs):
+        super(HTML, self).__init__(**kwargs)
+        self.register_preprocessor(TrappyPlotterPreprocessor, enabled=True)
+
+
 class TrappyPlotterPreprocessor(Preprocessor):
     """Preprocessor to remove Marked Lines from IPython Output Cells"""