test: add spec compliance validation against multibase.csv

.github/workflows/tox.yml

@@ -23,6 +23,8 @@ jobs:
       fail-fast: false
     steps:
       - uses: actions/checkout@v4
+        with:
+          submodules: true
       - uses: actions/setup-python@v5
         with:
           python-version: ${{ matrix.python-version }}
@@ -49,6 +51,8 @@ jobs:
       fail-fast: false
     steps:
       - uses: actions/checkout@v4
+        with:
+          submodules: true
       - name: Set up Python ${{ matrix.python-version }}
         uses: actions/setup-python@v5
         with:

.gitmodules

@@ -0,0 +1,3 @@
+[submodule "multibase-spec"]
+	path = multibase-spec
+	url = https://github.com/multiformats/multibase

tests/test_spec.py

@@ -0,0 +1,46 @@
+import csv
+from pathlib import Path
+
+from multibase.multibase import ENCODINGS
+
+
+def test_spec_encodings():
+    spec_path = Path(__file__).parent.parent / "multibase-spec" / "multibase.csv"
+    if not spec_path.exists():
+        # Fallback if the submodule is not checked out locally
+        return
+
+    spec_encodings = {}
+    with open(spec_path, encoding="utf-8") as f:
+        reader = csv.reader(f)
+        next(reader)  # skip header
+        for row in reader:
+            if not row:
+                continue
+            row = [col.strip() for col in row]
+            if len(row) >= 5:
+                unicode_str, character, encoding_name, description, status = row[:5]
+                if encoding_name == "none":
+                    continue
+                spec_encodings[encoding_name] = {
+                    "character": character,
+                    "status": status,
+                }
+
+    supported_names = set()
+    for enc in ENCODINGS:
+        if enc.encoding == "identity":
+            continue
+
+        assert enc.encoding in spec_encodings, f"Encoding '{enc.encoding}' not in spec"
+        spec_char = spec_encodings[enc.encoding]["character"]
+
+        assert enc.code.decode("utf-8") == spec_char, (
+            f"Prefix mismatch for '{enc.encoding}': expected '{spec_char}', got '{enc.code.decode('utf-8')}'"
+        )
+
+        supported_names.add(enc.encoding)
+
+    for name, data in spec_encodings.items():
+        if data["status"] == "final":
+            assert name in supported_names, f"Missing final encoding from spec: '{name}'"