Fix comparing _EOF with itself

dahuffman/huffmancodec.py

@@ -21,17 +21,18 @@ class _EndOfFileSymbol:
     def __repr__(self) -> str:
         return "_EOF"
 
+    def __eq__(self, other) -> bool:
+        return other.__class__ == self.__class__
+
     # Because _EOF will be compared with normal symbols (strings, bytes),
-    # we have to provide a minimal set of comparison methods.
-    # We'll make _EOF smaller than the rest (meaning lowest frequency)
+    # we have to provide a minimal set of comparison methods. We'll make
+    # _EOF smaller than all values other than itself since there will
+    # always be 1 and only 1 end of file per file.
     def __lt__(self, other) -> bool:
-        return True
+        return self != other
 
     def __gt__(self, other) -> bool:
-        return False
-
-    def __eq__(self, other) -> bool:
-        return other.__class__ == self.__class__
+        return self == other
 
     def __hash__(self) -> int:
         return hash(self.__class__)

tests/test_eof.py

@@ -0,0 +1,35 @@
+import pytest
+
+from dahuffman.huffmancodec import _EOF
+
+
+@pytest.fixture(params=(
+    b"\0",
+    b"abc",
+    "abc",
+    0,
+    100,
+    -1000,
+    False,
+    True,
+    None,
+    [],
+    (),
+    {},
+    [-100, 0, 10],
+    (-100, 10))
+)
+def to_compare(request):
+    return request.param
+
+
+class TestEndOfFileSymbol:
+
+    def test_eq(self):
+        assert _EOF == _EOF
+
+    def test_lt(self, to_compare):
+        assert _EOF < to_compare
+
+    def test_gt(self, to_compare):
+        assert to_compare > _EOF