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Description
Description
Currently, there is no mechanism to efficiently refer to specific node in syntax tree for the need of unit test. For example to create Diagnostic.highlights and attach them to a specific node in a syntax tree within diagnostic formatters unit tests. The absence of such a feature makes it cumbersome to identify and highlight syntax nodes for diagnostic or verification purposes.
Proposed Solution by @ahoppen:
Introduce a NodeLocator struct to facilitate the process. Below is a proposed implementation idea:
/// Refers to the first node in a syntax tree after `marker` that satisfies `match`.
///
/// For example, if you have
/// ```swift
/// var x: Int
/// 1️⃣func foo() {}
/// ```
///
/// Then `NodeLocator(marker: "1️⃣")` refers to the `CodeBlockItemSyntax` that
/// contains the function declaration and
/// `NodeLocator(marker: "1️⃣", matches: { $0.is(FunctionDeclSyntax.self) })`
/// refers to the function within.
struct NodeLocator {
let marker: String
let match: (Syntax) -> Bool = { _ in true }
func findNode(in tree: Syntax) -> Syntax? {
// TODO: Implement
}
}Note
Before starting implementation, let's discuss this approach here.
This feature could be a significant step towards enabling more precise and easier-to-write unit tests, especially those involving diagnostic highlights.