fix the constraint duplication in VersionRange

- add test for constraint duplicaton
- closes: #45

Signed-off-by: Keshav Priyadarshi <git@keshav.space>

src/univers/version_range.py

@@ -51,7 +51,7 @@ class VersionRange:
     constraints = attr.ib(type=tuple, default=attr.Factory(tuple))
 
     def __attrs_post_init__(self, *args, **kwargs):
-        constraints = tuple(sorted(self.constraints))
+        constraints = tuple(sorted(set(self.constraints)))
         # Notes: setattr is used because this is an immutable frozen instance.
         # See https://www.attrs.org/en/stable/init.html?#post-init
         object.__setattr__(self, "constraints", constraints)

tests/test_version_range.py

@@ -18,6 +18,7 @@
 from univers.version_range import RANGE_CLASS_BY_SCHEMES
 from univers.version_range import NpmVersionRange
 from univers.version_range import OpensslVersionRange
+from univers.version_range import NginxVersionRange
 from univers.versions import PypiVersion
 from univers.versions import NugetVersion
 from univers.versions import RubygemsVersion
@@ -278,6 +279,24 @@ def test_nuget_version_range(self):
         assert version_range == expected
         assert version_range.to_string() == "vers:nuget/>=1.0.0|<2.0.0"
 
+    def test_version_range_constraint_duplication(self):
+        version_range = VersionRange(
+            constraints=(
+                VersionConstraint(comparator=">=", version=SemverVersion(string="1.4.0")),
+                VersionConstraint(comparator=">=", version=SemverVersion(string="1.4.0")),
+                VersionConstraint(comparator="=", version=SemverVersion(string="2.5.0")),
+                VersionConstraint(comparator="=", version=SemverVersion(string="2.5.0")),
+            )
+        )
+
+        expected = VersionRange(
+            constraints=(
+                VersionConstraint(comparator=">=", version=SemverVersion(string="1.4.0")),
+                VersionConstraint(comparator="=", version=SemverVersion(string="2.5.0")),
+            )
+        )
+        assert version_range == expected
+
 
 VERSION_RANGE_TESTS_BY_SCHEME = {
     "nginx": ["0.8.40+", "0.7.52-0.8.39", "0.9.10", "1.5.0+, 1.4.1+"],