Add a libsass integration test

test/extra/sass_test.py

+# skip-if: 'clang' in os.environ['CC']
+# looks like libsass only builds using gcc...
+import os, sys, subprocess
+sys.path.append(os.path.dirname(__file__) + "/../lib")
+
+from test_helper import create_virtenv, run_test
+
+ENV_NAME = "sass_test_env_" + os.path.basename(sys.executable)
+SRC_DIR = os.path.abspath(os.path.join(ENV_NAME, "src"))
+PYTHON_EXE = os.path.abspath(os.path.join(ENV_NAME, "bin", "python"))
+SASS_DIR = os.path.abspath(os.path.join(ENV_NAME, "src", "libsass"))
+
+packages = ["six==1.10", "werkzeug==0.9"]
+packages += ["-e", "git+https://github.com/dahlia/libsass-python@0.8.3#egg=libsass"]
+create_virtenv(ENV_NAME, packages, force_create = True)
+
+expected = [{'ran': 75}]
+run_test([PYTHON_EXE, "setup.py", "test"], cwd=SASS_DIR, expected=expected)
+