Add support for Swift Testing

CHANGELOG.md

@@ -7,7 +7,7 @@
 
 ##### Enhancements
 
-- None.
+- Added support for Swift Testing.
 
 ##### Bug Fixes
 

Sources/Indexer/SwiftIndexer.swift

@@ -229,6 +229,7 @@ final class SwiftIndexer: Indexer {
             multiplexingSyntaxVisitor.visit()
 
             sourceFile.importStatements = importSyntaxVisitor.importStatements
+            sourceFile.importsSwiftTesting = importSyntaxVisitor.importStatements.contains(where: { $0.module == "Testing" })
 
             if !configuration.disableUnusedImportAnalysis {
                 for stmt in sourceFile.importStatements where stmt.isExported {

Sources/SourceGraph/Elements/SourceFile.swift

@@ -5,6 +5,7 @@ public class SourceFile {
     public let path: FilePath
     public let modules: Set<String>
     public var importStatements: [ImportStatement] = []
+    public var importsSwiftTesting = false
 
     public init(path: FilePath, modules: Set<String>) {
         self.path = path

Sources/SourceGraph/Mutators/SwiftTestingRetainer.swift

@@ -0,0 +1,35 @@
+import Configuration
+import Foundation
+import Shared
+
+/// Retains Swift Testing declarations.
+/// https://developer.apple.com/xcode/swift-testing/
+final class SwiftTestingRetainer: SourceGraphMutator {
+    private let graph: SourceGraph
+
+    required init(graph: SourceGraph, configuration _: Configuration, swiftVersion _: SwiftVersion) {
+        self.graph = graph
+    }
+
+    func mutate() {
+        for decl in graph.declarations(ofKinds: [.class, .struct]) {
+            guard decl.location.file.importsSwiftTesting else { continue }
+
+            if decl.attributes.contains("Suite") {
+                graph.markRetained(decl)
+            }
+        }
+
+        for decl in graph.declarations(ofKinds: [.functionFree, .functionMethodInstance, .functionMethodClass, .functionMethodStatic]) {
+            guard decl.location.file.importsSwiftTesting else { continue }
+
+            if decl.attributes.contains("Test") {
+                graph.markRetained(decl)
+
+                if let parent = decl.parent {
+                    graph.markRetained(parent)
+                }
+            }
+        }
+    }
+}

Sources/SourceGraph/SourceGraphMutatorRunner.swift

@@ -36,6 +36,7 @@ public final class SourceGraphMutatorRunner {
         EntryPointAttributeRetainer.self,
         PubliclyAccessibleRetainer.self,
         XCTestRetainer.self,
+        SwiftTestingRetainer.self,
         SwiftUIRetainer.self,
         StringInterpolationAppendInterpolationRetainer.self,
         PropertyWrapperRetainer.self,

Tests/Fixtures/Sources/RetentionFixtures/testRetainsSwiftTestingDeclarations.swift

@@ -0,0 +1,22 @@
+#if canImport(Testing)
+import Testing
+
+@Test func swiftTestingFreeFunction() {}
+
+class SwiftTestingClass {
+    @Test("displayName") func instanceMethod() {}
+    @Test class func classMethod() {}
+    @Test static func staticMethod() {}
+}
+
+@Suite struct SwiftTestingStructWithSuite {
+    @Test func instanceMethod() {}
+    @Test("displayName") static func staticMethod() {}
+}
+
+@Suite("displayName") class SwiftTestingClassWithSuite {
+    @Test func instanceMethod() {}
+    @Test("displayName") class func classMethod() {}
+    @Test static func staticMethod() {}
+}
+#endif

Tests/PeripheryTests/RetentionTest.swift

@@ -1059,6 +1059,33 @@ final class RetentionTest: FixtureSourceGraphTestCase {
         }
     }
 
+    // MARK: - Swift Testing
+
+    #if canImport(Testing)
+        func testRetainsSwiftTestingDeclarations() {
+            analyze {
+                assertReferenced(.functionFree("swiftTestingFreeFunction()"))
+
+                assertReferenced(.class("SwiftTestingClass")) {
+                    self.assertReferenced(.functionMethodInstance("instanceMethod()"))
+                    self.assertReferenced(.functionMethodClass("classMethod()"))
+                    self.assertReferenced(.functionMethodStatic("staticMethod()"))
+                }
+
+                assertReferenced(.struct("SwiftTestingStructWithSuite")) {
+                    self.assertReferenced(.functionMethodInstance("instanceMethod()"))
+                    self.assertReferenced(.functionMethodStatic("staticMethod()"))
+                }
+
+                assertReferenced(.class("SwiftTestingClassWithSuite")) {
+                    self.assertReferenced(.functionMethodInstance("instanceMethod()"))
+                    self.assertReferenced(.functionMethodClass("classMethod()"))
+                    self.assertReferenced(.functionMethodStatic("staticMethod()"))
+                }
+            }
+        }
+    #endif
+
     // MARK: - Assign-only properties
 
     func testStructImplicitInitializer() {