remove external dependency for parsing SA version

flask_sqlalchemy/utils.py

@@ -1,8 +1,22 @@
 
-from pkg_resources import parse_version
 import sqlalchemy
 
 
+def parse_version(v):
+    """
+        Take a string version and conver it to a tuple (for easier comparison), e.g.:
+
+            "1.2.3" --> (1, 2, 3)
+            "1.2" --> (1, 2, 0)
+            "1" --> (1, 0, 0)
+    """
+    parts = v.split(".")
+    # Pad the list to make sure there is three elements so that we get major, minor, point
+    # comparisons that default to "0" if not given.  I.e. "1.2" --> (1, 2, 0)
+    parts = (parts + 3 * ['0'])[:3]
+    return tuple(int(x) for x in parts)
+
+
 def sqlalchemy_version(op, val):
     sa_ver = parse_version(sqlalchemy.__version__)
     target_ver = parse_version(val)

tests/test_utils.py

@@ -4,6 +4,10 @@
 
 
 class TestSQLAlchemyVersion:
+    def test_parse_version(self):
+        assert utils.parse_version('1.2.3') == (1, 2, 3)
+        assert utils.parse_version('1.2') == (1, 2, 0)
+        assert utils.parse_version('1') == (1, 0, 0)
 
     @mock.patch.object(utils, 'sqlalchemy')
     def test_sqlalchemy_version(self, m_sqlalchemy):