Extract rule: template-no-unnecessary-component-helper

[NullVoxPopuli]

Split from #2371.

[NullVoxPopuli-ai-agent]

Review: template-no-unnecessary-component-helper (comparing with ember-template-lint no-unnecessary-component-helper)

Coverage

Good migration that covers the key behavior of the original rule.

What's done well

• Correct detection logic: isComponentWithStringLiteral checks the same conditions as the original -- path.original === 'component', first param is a StringLiteral, and the string doesn't contain @ (addon-scoped names).
• Attribute-safe namespace tracking: The inAttribute counter correctly mirrors the original's inSafeNamespace pattern (using AttrNode enter/exit), ensuring that {{component "name"}} inside attribute values is not flagged. This is a key behavior of the original.
• Auto-fix for MustacheStatement and SubExpression: Fixes correctly reconstruct the invocation by stripping the component helper and using the component name directly.
• No fix for BlockStatement: Correctly does not attempt to fix block invocations (matching the original's more complex block fix that may not translate cleanly).
• Comprehensive tests: Good coverage of valid/invalid cases in both gjs and hbs modes.

Items needing attention

1. SubExpression handling is an addition: The original only handles MustacheStatement and BlockStatement visitors. This PR adds GlimmerSubExpression handling. While this is arguably a useful extension, it goes beyond the original rule's scope. The original explicitly only visits AttrNode, BlockStatement, and MustacheStatement. In practice, a sub-expression like (component "foo") in a non-attribute context is unusual, so this may be fine, but it's worth flagging as a divergence.

2. (component "my-component") in HBS valid tests: The HBS valid test includes '(component "my-component")' as valid. This is correct because in HBS mode, a bare sub-expression at the top level is unusual, but more importantly, the rule correctly exempts sub-expressions in attribute contexts. However, the gjs tests don't test this case explicitly.

3. Error message difference: Original says "Invoke component directly instead of using \component` helper", while the PR says "Unnecessary use of (component) helper. Use the component name directly."`. The PR message is arguably clearer and more actionable.

Verdict

Solid migration. The SubExpression addition is a minor divergence worth documenting but is a reasonable enhancement. Test coverage is good.

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