Merge pull request #318 from GladysNalvarte/test_images

Checks if the environment.yml file is empty and if it contains a dict…

repo2docker/buildpacks/conda/__init__.py

@@ -136,6 +136,12 @@ class CondaBuildPack(BaseImage):
             py_version = None
             with open(environment_yml) as f:
                 env = YAML().load(f)
+                # check if the env file is empty, if so instantiate an empty dictionary.
+                if env is None:
+                    env = {}
+                # check if the env file has a dictionary not a list or other data structure.
+                if not isinstance(env, dict):
+                    raise TypeError("environment.yml should contain a dictionary. Got %r" % type(env))
                 for dep in env.get('dependencies', []):
                     if not isinstance(dep, str):
                         continue

tests/test_env_yml.py

@@ -0,0 +1,26 @@
+"""
+Test if the environment.yml is empty or it constains other data structure than a dictionary
+"""
+import os
+import sys
+import pytest
+from repo2docker import buildpacks
+
+
+def test_empty_env_yml(tmpdir):
+    tmpdir.chdir()
+    p = tmpdir.join("environment.yml")
+    p.write("")
+    bp = buildpacks.CondaBuildPack()
+    py_ver = bp.python_version
+    # If the environment.yml is empty python_version will get an empty string
+    assert py_ver == ''
+
+def test_no_dict_env_yml(tmpdir):
+    tmpdir.chdir()
+    q = tmpdir.join("environment.yml")
+    q.write("numpy\n "
+            "matplotlib\n")
+    bq = buildpacks.CondaBuildPack()
+    with pytest.raises(TypeError):
+        py_ver = bq.python_version