add tests

tests/test.py

@@ -0,0 +1,25 @@
+import unittest
+import materials
+import json
+import shlex
+import subprocess
+
+
+class TestGet(unittest.TestCase):
+
+  def test_property(self):
+    self.assertEqual(materials.get_value(json.loads('{"rho": 2.5}'), "rho"), 2.5, "Should be 6")
+
+  def test_property_nested(self):
+    self.assertEqual(materials.get_value(json.loads('{"node": {"rho": 2.5}}'), "node/rho"), 2.5, "Should be 6")
+
+class TestCLI(unittest.TestCase):
+
+  def test_property(self):
+    cmd = shlex.split("materials get Al -r")
+    output = subprocess.check_output(cmd).decode('utf-8').strip()
+    self.assertEqual(output, '2.6989 g/cm³')
+
+
+if __name__ == '__main__':
+    unittest.main()