Add unit test for conda environment management

- Also fix a bug caught by unit test!

tests/test_conda.py

@@ -0,0 +1,53 @@
+"""
+Test conda commandline wrappers
+"""
+from tljh import conda
+import os
+import pytest
+import subprocess
+import tempfile
+
+
+@pytest.fixture
+def prefix():
+    """
+    Provide a temporary directory to make environments in.
+    """
+    with tempfile.TemporaryDirectory() as tmpdir:
+        yield tmpdir
+
+
+def test_create_environment(prefix):
+    """
+    Test conda environment creation
+
+    An empty conda environment doesn't seem to have anything in it,
+    so we just check for directory existence.
+    """
+    conda.ensure_conda_env(prefix)
+    assert os.path.exists(prefix)
+
+
+def test_ensure_environment(prefix):
+    """
+    Test second call to ensure_conda_env works as expected
+
+    A conda environment already exists, so we it should just do nothing
+    """
+    conda.ensure_conda_env(prefix)
+    assert os.path.exists(prefix)
+    conda.ensure_conda_env(prefix)
+
+
+def test_ensure_packages(prefix):
+    """
+    Test installing packages in conda environment
+    """
+    conda.ensure_conda_env(prefix)
+    conda.ensure_conda_packages(prefix, ['numpy'])
+    # Throws an error if this fails
+    subprocess.check_call([
+        os.path.join(prefix, 'bin', 'python'),
+        '-c',
+        'import numpy'
+    ])

tljh/conda.py

@@ -26,7 +26,7 @@ def ensure_conda_env(prefix):
 
 def ensure_conda_packages(prefix, packages):
     """
-    Ensure packages are installed in the conda prefix
+    Ensure packages are installed in the conda prefix.
     """
     abspath = os.path.abspath(prefix)
     # Let subprocess errors propagate
@@ -41,7 +41,8 @@ def ensure_conda_packages(prefix, packages):
     # parse this outside of this kludge.
     filtered_output = '\n'.join([
         l for l in raw_output.split('\n')
-        if not l.startswith('{"fetch"')
+        # Sometimes the JSON messages start with a \00. The lstrip removes these.
+        if not l.lstrip().startswith('{"fetch"')
     ])
     output = json.loads(filtered_output)
     if 'success' in output and output['success'] == True: