Fix legacy dockerfile buildpack and add tests

repo2docker/detectors.py

@@ -686,7 +686,7 @@ class DockerBuildPack(BuildPack):
         ):
             yield line
 
-class LegacyBinderDockerBuildPack(BuildPack):
+class LegacyBinderDockerBuildPack(DockerBuildPack):
 
     name = 'Legacy Binder Dockerfile'
 

tests/dockerfile/legacy/Dockerfile

@@ -0,0 +1,15 @@
+FROM andrewosh/binder-base
+
+USER root
+
+# Add Julia dependencies
+RUN apt-get update
+RUN apt-get install -y julia libnettle4 && apt-get clean
+
+USER main
+
+# Install Julia kernel
+RUN julia -e 'Pkg.add("IJulia")'
+RUN julia -e 'Pkg.add("Gadfly")' && julia -e 'Pkg.add("RDatasets")'
+
+ADD verify verify

tests/dockerfile/legacy/verify

@@ -0,0 +1,6 @@
+#!/usr/bin/env python
+import sys
+
+assert sys.version_info[:2] == (2, 7)
+
+import jupyter