No spec compliance test validating `constants.py` against `table.csv`

[sumanjeet0012]

There is no test that validates the contents of constants.py against the authoritative upstream multicodec table.csv. This means the codec table can silently drift from the spec — codecs can be missing, have wrong codes, or be extra.

Problem

The CODECS dict in constants.py is generated from table.csv by tools/update-table.py, but:

• The generation is manual (not automated in CI)
• There is no test that verifies the generated output matches the source CSV
• A developer could hand-edit constants.py and introduce inconsistencies
• Codecs added to the upstream CSV won't be detected as missing

go-multicodec has a spec compliance test (TestSpec) that validates its generated code against the CSV:

func TestSpec(t *testing.T) {
    // Reads multicodec/table.csv
    // Validates every entry matches the generated code
}

Proposed Solution

1. Add the multicodec spec as a git submodule or download table.csv in CI:

   git submodule add https://github.com/multiformats/multicodec multicodec-spec

2. Create tests/test_spec.py with a test that:

   • Reads multicodec-spec/table.csv
   • Verifies every CSV entry with tag != "none" exists in CODECS with the correct prefix
   • Verifies no extra entries exist in CODECS that aren't in the CSV
   • Verifies NAME_TABLE and CODE_TABLE are consistent with CODECS

3. Example test structure:

   def test_spec_table_completeness():
       """Every entry in table.csv should be in CODECS."""
       csv_entries = load_csv("multicodec-spec/table.csv")
       for name, tag, code, status, desc in csv_entries:
           if tag == "none":
               continue
           assert name in NAME_TABLE, f"Missing codec: {name} ({code})"
           assert NAME_TABLE[name] == int(code, 16), f"Code mismatch for {name}"

Related

• Go spec test: go-multicodec code_test.go
• Upstream CSV: multicodec/table.csv