Add tests for pmxbot command (and Result.results).

conftest.py

@@ -1,4 +1,32 @@
+import os
+
 import six
 
+import pytest
+
+import wolframalpha
+
+
 if six.PY2:
-    collect_ignore = ['wolframalpha/pmxbot.py']
+    collect_ignore = [
+    	'wolframalpha/pmxbot.py',
+    	'wolframalpha/test_pmxbot.py',
+    ]
+
+
+@pytest.fixture(scope='session')
+def API_key():
+	"""
+	To run the tests fully, the environment must be configured
+	with a WOLFRAMALPHA_API_KEY environment variable. Otherwise,
+	skip them.
+	"""
+	try:
+		return os.environ['WOLFRAMALPHA_API_KEY']
+	except KeyError:
+		pytest.skip("Need WOLFRAMALPHA_API_KEY in environment")
+
+
+@pytest.fixture(scope='session')
+def client(API_key):
+	return wolframalpha.Client(API_key)