Replace setTestFilter with makeTestFilter.

Sources/Testing/Running/Configuration.swift

@@ -118,7 +118,7 @@ public struct Configuration: Sendable {
   /// - Returns: A Boolean value representing if the test satisfied the filter.
   public typealias TestFilter = @Sendable (_ test: Test) -> Bool
 
-  /// Storage for ``testFilter``.
+  /// Storage for ``testFilter-swift.property``.
   private var _testFilter: TestFilter = { !$0.isHidden }
 
   /// The test filter to which tests should be filtered when run.
@@ -130,36 +130,24 @@ public struct Configuration: Sendable {
       // By default, the test filter should always filter out hidden tests. This
       // is the appropriate behavior for external clients of this SPI. If the
       // testing library needs to enable hidden tests in its own test targets,
-      // it should use setTestFilter(toMatch:includeHiddenTests:) instead.
+      // it can instead use `uncheckedTestFilter`.
       _testFilter = { test in
         !test.isHidden && newValue(test)
       }
     }
   }
 
-  /// Filter tests to run to those specified via a set of test IDs.
-  ///
-  /// - Parameters:
-  ///   - selection: A set of test IDs to be filtered.
-  ///
-  /// By default, all tests are run and no filter is set.
-  public mutating func setTestFilter(toMatch selection: Set<Test.ID>) {
-    setTestFilter(toMatch: Test.ID.Selection(testIDs: selection), includeHiddenTests: false)
-  }
-
-  /// Filter tests to run to those specified by a selection of test IDs.
-  ///
-  /// - Parameters:
-  ///   - selection: A selection of test IDs to be filtered.
-  ///   - includeHiddenTests: If false, a test annotated with the `.hidden`
-  ///     trait will not be included, even if its ID is present in `selection`.
+  /// The test filter to which tests should be filtered when run.
   ///
-  /// By default, all tests are run and no filter is set.
-  mutating func setTestFilter(toMatch selection: Test.ID.Selection, includeHiddenTests: Bool) {
-    if includeHiddenTests {
-      _testFilter = selection.contains
-    } else {
-      testFilter = selection.contains
+  /// Unlike ``testFilter-swift.property``, this property does not impose any
+  /// checks for hidden tests. It is used by the testing library to run hidden
+  /// tests; other callers should always use ``testFilter-swift.property``.
+  var uncheckedTestFilter: TestFilter {
+    get {
+      _testFilter
+    }
+    set {
+      _testFilter = newValue
     }
   }
 
@@ -180,3 +168,38 @@ public struct Configuration: Sendable {
   @_spi(ExperimentalParameterizedTesting)
   public var testCaseFilter: TestCaseFilter = { _, _ in true }
 }
+
+// MARK: - Test filter factory functions
+
+/// Make a test filter that filters tests to those specified by a set of test
+/// IDs.
+///
+/// - Parameters:
+///   - selection: A set of test IDs to be filtered.
+///
+/// By default, all tests are run and no filter is set.
+@_spi(ExperimentalTestRunning)
+public func makeTestFilter(matching selection: some Collection<Test.ID>) -> Configuration.TestFilter {
+  let selection = Test.ID.Selection(testIDs: selection)
+  return makeTestFilter(matching: selection, includeHiddenTests: false)
+}
+
+/// Make a test filter that filters tests to those specified by a set of test
+/// IDs, optionally including or excluding hidden tests.
+///
+/// - Parameters:
+///   - selection: A selection of test IDs to be filtered.
+///   - includeHiddenTests: If false, a test annotated with the `.hidden`
+///     trait will not be included, even if its ID is present in `selection`.
+///
+/// By default, all tests are run and no filter is set.
+func makeTestFilter(matching selection: Test.ID.Selection, includeHiddenTests: Bool) -> Configuration.TestFilter {
+  if includeHiddenTests {
+    return selection.contains
+  } else {
+    return { test in
+      !test.isHidden && selection.contains(test)
+    }
+  }
+}
+

Sources/Testing/Running/XCTestScaffold.swift

@@ -211,7 +211,7 @@ public enum XCTestScaffold: Sendable {
     var configuration = Configuration()
     configuration.isParallelizationEnabled = false
     if let testIDs {
-      configuration.setTestFilter(toMatch: Set(testIDs))
+      configuration.testFilter = makeTestFilter(matching: testIDs)
     }
     if let tags {
       // Check if the test's tags intersect the set of selected tags. If there

Tests/TestingTests/PlanTests.swift

@@ -28,7 +28,7 @@ struct PlanTests {
 
     let selection = Test.ID.Selection(testIDs: [innerTestType.id])
     var configuration = Configuration()
-    configuration.setTestFilter(toMatch: selection, includeHiddenTests: true)
+    configuration.uncheckedTestFilter = makeTestFilter(matching: selection, includeHiddenTests: true)
 
     let plan = await Runner.Plan(tests: tests, configuration: configuration)
     #expect(plan.steps.contains(where: { $0.test == outerTestType }))
@@ -53,7 +53,7 @@ struct PlanTests {
 
     var configuration = Configuration()
     let selection = Test.ID.Selection(testIDs: [innerTestType.id, outerTestType.id])
-    configuration.setTestFilter(toMatch: selection, includeHiddenTests: true)
+    configuration.uncheckedTestFilter = makeTestFilter(matching: selection, includeHiddenTests: true)
 
     let plan = await Runner.Plan(tests: tests, configuration: configuration)
     let planTests = plan.steps.map(\.test)
@@ -73,7 +73,7 @@ struct PlanTests {
 
     var configuration = Configuration()
     let selection = Test.ID.Selection(testIDs: [outerTestType.id, deeplyNestedTest.id])
-    configuration.setTestFilter(toMatch: selection, includeHiddenTests: true)
+    configuration.uncheckedTestFilter = makeTestFilter(matching: selection, includeHiddenTests: true)
 
     let plan = await Runner.Plan(tests: tests, configuration: configuration)
 
@@ -92,7 +92,7 @@ struct PlanTests {
 
     var configuration = Configuration()
     let selection = Test.ID.Selection(testIDs: [testSuiteA.id])
-    configuration.setTestFilter(toMatch: selection, includeHiddenTests: true)
+    configuration.uncheckedTestFilter = makeTestFilter(matching: selection, includeHiddenTests: true)
 
     let plan = await Runner.Plan(tests: tests, configuration: configuration)
     let testFuncXWithTraits = try #require(plan.steps.map(\.test).first { $0.name == "x()" })

Tests/TestingTests/Runner.Plan.SnapshotTests.swift

@@ -22,7 +22,7 @@ struct Runner_Plan_SnapshotTests {
     let suite = try #require(await test(for: Runner_Plan_SnapshotFixtures.self))
 
     var configuration = Configuration()
-    configuration.setTestFilter(toMatch: .init(testIDs: [suite.id]), includeHiddenTests: true)
+    configuration.uncheckedTestFilter = makeTestFilter(matching: .init(testIDs: [suite.id]), includeHiddenTests: true)
 
     let plan = await Runner.Plan(configuration: configuration)
     let snapshot = Runner.Plan.Snapshot(snapshotting: plan)

Tests/TestingTests/RunnerTests.swift

@@ -251,7 +251,7 @@ final class RunnerTests: XCTestCase {
 
     var configuration = Configuration()
     let selection = Test.ID.Selection(testIDs: [testSuite.id])
-    configuration.setTestFilter(toMatch: selection, includeHiddenTests: true)
+    configuration.uncheckedTestFilter = makeTestFilter(matching: selection, includeHiddenTests: true)
 
     let runner = await Runner(testing: [
       testSuite,
@@ -302,7 +302,7 @@ final class RunnerTests: XCTestCase {
 
     var configuration = Configuration()
     let selection = Test.ID.Selection(testIDs: selectedTestIDs)
-    configuration.setTestFilter(toMatch: selection, includeHiddenTests: true)
+    configuration.uncheckedTestFilter = makeTestFilter(matching: selection, includeHiddenTests: true)
 
     let runner = await Runner(configuration: configuration)
     let plan = runner.plan
@@ -326,10 +326,10 @@ final class RunnerTests: XCTestCase {
     ]
 
     var configuration1 = Configuration()
-    configuration1.setTestFilter(toMatch: .init(testIDs: selectedTestIDs), includeHiddenTests: false)
+    configuration1.testFilter = makeTestFilter(matching: .init(testIDs: selectedTestIDs), includeHiddenTests: false)
 
     var configuration2 = Configuration()
-    configuration2.setTestFilter(toMatch: selectedTestIDs)
+    configuration2.testFilter = makeTestFilter(matching: selectedTestIDs)
 
     for configuration in [configuration1, configuration2] {
       let runner = await Runner(configuration: configuration)

Tests/TestingTests/TestSupport/TestingAdditions.swift

@@ -68,7 +68,7 @@ func runTest(for containingType: Any.Type, configuration: Configuration = .init(
 func runTestFunction(named name: String, in containingType: Any.Type, configuration: Configuration = .init()) async {
   var configuration = configuration
   let selection = Test.ID.Selection(testIDs: [Test.ID(type: containingType).child(named: name)])
-  configuration.setTestFilter(toMatch: selection, includeHiddenTests: true)
+  configuration.uncheckedTestFilter = makeTestFilter(matching: selection, includeHiddenTests: true)
 
   let runner = await Runner(configuration: configuration)
   await runner.run()
@@ -92,7 +92,7 @@ extension Runner {
 
     var configuration = configuration
     let selection = Test.ID.Selection(testIDs: [Test.ID(moduleName: moduleName, nameComponents: [testName], sourceLocation: nil)])
-    configuration.setTestFilter(toMatch: selection, includeHiddenTests: true)
+    configuration.uncheckedTestFilter = makeTestFilter(matching: selection, includeHiddenTests: true)
 
     await self.init(configuration: configuration)
   }
@@ -107,7 +107,7 @@ extension Runner.Plan {
   init(selecting containingType: Any.Type, configuration: Configuration = .init()) async {
     var configuration = configuration
     let selection = Test.ID.Selection(testIDs: [Test.ID(type: containingType)])
-    configuration.setTestFilter(toMatch: selection, includeHiddenTests: true)
+    configuration.uncheckedTestFilter = makeTestFilter(matching: selection, includeHiddenTests: true)
 
     await self.init(configuration: configuration)
   }