Add automatic update checks

tests/test_updater.py

@@ -0,0 +1,18 @@
+import unittest
+
+from nlprog.updater import VERSION_RE, _version_tuple
+
+
+class UpdaterTests(unittest.TestCase):
+    def test_version_regex_reads_pyproject_version(self):
+        match = VERSION_RE.search('[project]\nname = "nlprog"\nversion = "0.2.0"\n')
+        self.assertIsNotNone(match)
+        self.assertEqual(match.group(1), "0.2.0")
+
+    def test_version_tuple_compares_numeric_versions(self):
+        self.assertGreater(_version_tuple("0.10.0"), _version_tuple("0.2.0"))
+        self.assertEqual(_version_tuple("1.2.3"), (1, 2, 3))
+
+
+if __name__ == "__main__":
+    unittest.main()