feat: Add unittest coverage

tests/test_codec.py

@@ -0,0 +1,41 @@
+import gzip
+import pathlib
+import sys
+import unittest
+import zlib
+
+
+ROOT = pathlib.Path(__file__).resolve().parents[1]
+SRC = ROOT / "src"
+if str(SRC) not in sys.path:
+    sys.path.insert(0, str(SRC))
+
+from core import codec
+
+
+class CodecTests(unittest.TestCase):
+    def test_supported_encodings_always_include_gzip_and_deflate(self):
+        encodings = codec.supported_encodings()
+        self.assertIn("gzip", encodings)
+        self.assertIn("deflate", encodings)
+
+    def test_decode_passes_through_unknown_empty_and_invalid_payloads(self):
+        raw = b"plain-body"
+        self.assertIs(codec.decode(raw, ""), raw)
+        self.assertIs(codec.decode(raw, "identity"), raw)
+        self.assertIs(codec.decode(raw, "unknown"), raw)
+        self.assertEqual(codec.decode(raw, "gzip"), raw)
+
+    def test_decode_gzip_and_deflate(self):
+        raw = b"hello through compression"
+        gzip_body = gzip.compress(raw)
+        zlib_body = zlib.compress(raw)
+        raw_deflate_body = zlib.compress(raw, wbits=-zlib.MAX_WBITS)
+
+        self.assertEqual(codec.decode(gzip_body, "gzip"), raw)
+        self.assertEqual(codec.decode(zlib_body, "deflate"), raw)
+        self.assertEqual(codec.decode(raw_deflate_body, "deflate"), raw)
+
+
+if __name__ == "__main__":
+    unittest.main()