Fix invert() for ranges made only of != constraints

CHANGELOG.rst

@@ -1,6 +1,12 @@
 Changelog
 =========
 
+Next release
+------------
+
+- Fix ``VersionRange.invert()`` for enumerated ranges: a range made only of ``!=`` constraints now contains every version other than the excluded ones. https://github.com/aboutcode-org/univers/issues/214
+
+
 Version v32.0.1
 ----------------
 

src/univers/version_constraint.py

@@ -517,9 +517,13 @@ def contains_version(version, constraints):
     # Split the constraint list in two sub lists:
     #   a first list where the comparator is "=" or "!="
     #   a second list where the comparator is neither "=" nor "!="
+    equality_constraints = constraints
     constraints = [c for c in constraints if c.comparator not in ("=", "!=")]
     if not constraints:
-        return False
+        # Only "=" and "!=" constraints are left. When all of them are "!=", the
+        # range is made of every version except the excluded ones, and the
+        # "tested version" was already checked against all of these above.
+        return all(c.comparator == "!=" for c in equality_constraints)
 
     # If we end up with constraints list contains only one item.
     if len(constraints) == 1:

tests/test_version_range.py

@@ -458,3 +458,44 @@ def test_version_range_lexicographic():
     assert LexicographicVersion(-123) in VersionRange.from_string("vers:lexicographic/<~")
     assert LexicographicVersion(None) in VersionRange.from_string("vers:lexicographic/*")
     assert LexicographicVersion("ABC") in VersionRange.from_string("vers:lexicographic/>abc|<=None")
+
+
+def test_range_with_only_unequal_constraints_contains_all_other_versions():
+    vers_range = VersionRange.from_string("vers:pypi/!=1.0.0|!=2.0.0")
+    version_class = vers_range.version_class
+    assert version_class("1.0.0") not in vers_range
+    assert version_class("2.0.0") not in vers_range
+    assert version_class("0.5.0") in vers_range
+    assert version_class("1.5.0") in vers_range
+    assert version_class("3.0.0") in vers_range
+
+
+def test_invert_enumerated_range_is_the_complement():
+    # https://github.com/aboutcode-org/univers/issues/214
+    vers_range = VersionRange.from_string("vers:pypi/1.0.0|2.0.0")
+    inverse = vers_range.invert()
+    assert str(inverse) == "vers:pypi/!=1.0.0|!=2.0.0"
+    version_class = vers_range.version_class
+    for version in ("0.5.0", "1.0.0", "1.5.0", "2.0.0", "3.0.0"):
+        version = version_class(version)
+        assert (version in vers_range) != (version in inverse)
+
+
+def test_invert_twice_of_enumerated_range_gives_the_same_range():
+    vers_range = VersionRange.from_string("vers:gem/1.0|2.0|3.0")
+    assert vers_range.invert().invert() == vers_range
+    inverse = vers_range.invert()
+    version_class = vers_range.version_class
+    for version in ("0.1", "1.0", "1.5", "2.0", "2.5", "3.0", "4.0"):
+        version = version_class(version)
+        assert (version in vers_range) != (version in inverse)
+
+
+def test_range_mixing_equal_and_unequal_constraints_only_contains_equal_versions():
+    vers_range = VersionRange.from_string("vers:pypi/1.0.0|!=2.0.0")
+    version_class = vers_range.version_class
+    assert version_class("1.0.0") in vers_range
+    assert version_class("2.0.0") not in vers_range
+    assert version_class("0.5.0") not in vers_range
+    assert version_class("1.5.0") not in vers_range
+    assert version_class("3.0.0") not in vers_range