`testRequireContractNameAcceptedNamesCannotTraverse` asserts nothing on 95% of its runs

[thedavidmeister]

Audit scope: whole-repo, commit 7aa85a4

Dimension 2 (test coverage) / 5 (correctness/intent) · medium

Location: test/src/lib/LibCodeGen.requireContractName.t.sol:159-170

Path note: PR #56 is open and unmerged as of filing. On main today this file is test/lib/LibCodeGen.requireContractName.t.sol; it becomes test/src/lib/LibCodeGen.requireContractName.t.sol after #56 merges.

Problem

try … catch {} — the empty catch means a rejected name passes the test having
asserted nothing, and the catch is untyped, so an unexpected revert also counts
as a pass. Measured at --fuzz-seed 1, 2048 runs: 101 accepted, 1947 silently
skipped. The property named in the title (accepted ⟹ no filesystem-meaningful
byte) is proven on 4.9% of the budget.

Constructing names with nameFromSeedSlow would not fix it — that would make the
assertion a property of the generator's alphabet rather than of
requireContractName.

Proposed fix

Prove it deterministically and completely instead.
testRequireContractNameMatchesAlphabet (line 207) already establishes accepted
⟹ every byte ∈ SLOW_TAIL_ALPHABET over arbitrary bytes; the missing half is a
property of the alphabet itself. Delete lines 155-170 and add (verified passing):

/// The identifier alphabet contains no byte that means anything to a
/// filesystem, so no accepted name can leave the directory it is interpolated
/// into. Stated over the alphabet rather than waiting for the fuzzer to produce
/// an accepted name; with `testRequireContractNameMatchesAlphabet`, which pins
/// accepted names to that alphabet, this covers the whole accepted set.
function testRequireContractNameAlphabetCannotTraverse() external pure {
    bytes memory tail = bytes(SLOW_TAIL_ALPHABET);
    for (uint256 i = 0; i < tail.length; i++) {
        assertNotEq(uint8(tail[i]), uint8(bytes1("/")), "separator in the alphabet");
        assertNotEq(uint8(tail[i]), uint8(bytes1("\\")), "backslash in the alphabet");
        assertNotEq(uint8(tail[i]), uint8(bytes1(".")), "dot in the alphabet");
        assertNotEq(uint8(tail[i]), uint8(bytes1(hex"00")), "nul in the alphabet");
    }
}