Make identifier case insensitive

Ref. #520

rflx/identifier.py

@@ -27,7 +27,12 @@ def __init__(
 
     def __eq__(self, other: object) -> bool:
         if isinstance(other, self.__class__):
-            return self.parts == other.parts
+            if len(self.parts) != len(other.parts):
+                return False
+            for s, o in zip(self.parts, other.parts):
+                if s.lower() != o.lower():
+                    return False
+            return True
         return NotImplemented
 
     def __lt__(self, other: object) -> bool:
@@ -36,7 +41,7 @@ def __lt__(self, other: object) -> bool:
         return NotImplemented
 
     def __hash__(self) -> int:
-        return hash(tuple(self.parts))
+        return hash(tuple(map(str.lower, self.parts)))
 
     def __repr__(self) -> str:
         return f'ID("{self}")'

tests/unit/identifier_test.py

@@ -60,6 +60,14 @@ def test_id_invalid_colon() -> None:
         ID("A::B:C::D")
 
 
+def test_id_eq() -> None:
+    assert ID("A") == ID("a")
+
+
+def test_id_hash() -> None:
+    assert hash(ID("A")) == hash(ID("a"))
+
+
 def test_id_str() -> None:
     assert str(ID("A::B::C")) == "A::B::C"