swiftlang/swift-package-manager

Update macro template to support Swift Testing tests

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#8890 opened on Jul 2, 2025

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enhancementgood first issueswift package init

Description

According to the SwiftPM code base, we are unable to use Swift Testing to verify macros. However, the referenced GitHub issue (https://github.com/swiftlang/swift-syntax/issues/2400) is closed.

The Swift Syntax 600 release notes mentions SwiftSyntaxMacrosGenericTestSupport.

Here is a snippet of the relevant Swift Syntax release notes

SwiftSyntaxMacrosGenericTestSupport

  • Description: A version of the SwiftSyntaxMacrosTestSupport module that doesn't depend on Foundation or XCTest and can thus be used to write macro tests using swift-testing. Since swift-syntax can't depend on swift-testing (which would incur a circular dependency since swift-testing depends on swift-syntax), users need to manually specify a failure handler like the following, that fails the swift-testing test: Issue.record("\($0.message)", fileID: $0.location.fileID, filePath: $0.location.filePath, line: $0.location.line, column: $0.location.column)
  • Pull request: https://github.com/swiftlang/swift-syntax/pull/2647

The SwiftPM template for swift package init --type macro should be update to provide an idiomatic way to write a Swift Testing test to verify and validate a macro.

Contributor guide

Tech stack
swift
Domain
testingdeveloper experience
Issue type
feature
DifficultyEstimated implementation difficulty for a new contributor, from 1 for very small changes to 5 for expert-level work.
2
Estimated timeA rough time range for an experienced contributor to investigate, implement, test, and prepare a pull request.
half day
Activity statusHow available the issue appears right now: fresh, active, stale, blocked, or waiting on maintainer input.
fresh
ClarityHow clearly the issue explains the expected change, acceptance criteria, and next step.
clear
Prerequisites
Swift programmingSwiftPM template systemSwift Testing framework
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
68
Research direction
Start by examining the current macro template in `Sources/Workspace/InitPackage.swift` around lines 119-122. Review the Swift Syntax 600 release notes and the linked PR #2647 to understand the `SwiftSyntaxMacrosGenericTestSupport` module and the required failure handler. Then, update the template to include a simple macro test example using swift testing, following the pattern shown in the release notes.