Parenthesized chained assertions not detected as unsafe_double_type_assertion #27

Finding

When a chained assertion is wrapped in parentheses — such as (value as unknown) as any — the detector does not classify it as unsafe_double_type_assertion. Instead it falls through to the generic single-assertion branch (or produces a different finding), because the outer AsExpression.expression is a ParenthesizedExpression, not an AsExpression.

Evidence

Reported by CodeRabbit review on PR #24 (commit 3a9b942): the visitor checks ts.isAsExpression(node.expression) which fails for parenthesized chains.

// This pattern is NOT detected as a chained assertion:
const x = (value as unknown) as any;
// AST: AsExpression → ParenthesizedExpression → AsExpression

Removing the parentheses makes it detectable:

// This pattern IS detected as a chained assertion:
const x = value as unknown as any;

Requirements

• (value as X) as Y must be classified as unsafe_double_type_assertion with assertionForm: chained_as.
• (value as X) as any must produce both unsafe_double_type_assertion and unsafe_type_assertion independently.
• ((value as X) as Y) as Z (nested parens) must still be detected.
• Non-chained parenthesized expressions must not be affected.
• Existing chain-count tests must continue to pass.

Constraints

• Do not change finding types or severity.
• Do not affect non-chained single assertions.
• Do not modify suppression behavior.
• Do not exceed the existing per-AST-node finding-count semantics.
• Do not add dependencies.

Validation

Add tests (RED before fix, GREEN after) for:

1. (value as X) as Y → 1 finding, unsafe_double_type_assertion
2. (value as unknown) as any → 2 findings (double + any)
3. ((value as X) as Y) as Z → 2 findings
4. (value) as any (unnecessary parens around expression, not chain) → 1 finding unsafe_type_assertion
5. (value as X) as Y as Z → 2 findings (outer chain + inner chain)
6. Existing 1-chain, 2-chain, 3-chain, 4-chain tests unchanged

Rollback

A reverted commit restores current parenthesized detection behavior.