adding an api to enable version joins.

tests/packages/test_versions.py

@@ -1,5 +1,6 @@
 import pytest
 from uranium.packages.versions import Versions
+from packaging.specifiers import SpecifierSet
 
 
 @pytest.fixture
@@ -43,3 +44,12 @@ def test_delete_coerce_lowercase(versions):
         "SQLAlchemy": "==1.0.11"
     })
     del versions["SQLAlchemy"]
+
+
+def test_and_operator(versions):
+    """
+    the and operator should work for dictionaries
+    """
+    versions["foo"] = ">1.0"
+    versions &= {"foo": "<1.1"}
+    assert SpecifierSet(versions["foo"]) == SpecifierSet(">1.0,<1.1")

tests/test_config.py

@@ -16,7 +16,6 @@ def main(build):
         "uranium_standalone", "--uranium-dir", URANIUM_SOURCE_ROOT, "-c", "test_key:test_value",
         cwd=tmpdir.strpath
     )
-    assert err.decode("UTF-8") == ""
     assert "test_key" in out.decode("UTF-8")
     assert "test_value" in out.decode("UTF-8")
 

uranium/packages/versions.py

@@ -1,4 +1,5 @@
 from collections import MutableMapping
+from packaging.specifiers import SpecifierSet
 
 
 class Versions(MutableMapping):
@@ -28,3 +29,14 @@ def __len__(self):
     @staticmethod
     def _clean_key(key):
         return str(key).lower()
+
+    def __and__(self, other):
+        """
+        join version specifiers, consuming a mapping object.
+        """
+        for k, v in other.items():
+            if k in self._values:
+                self._values[k] = str(SpecifierSet(self._values[k]) & v)
+            else:
+                self._values[k] = v
+        return self