Refactor the test observer to extract xUnit recording from the XCTest…

… observer.

This is work done in preparation for supporting the swift-testing framework.

PiperOrigin-RevId: 662617920

tools/test_discoverer/ObjcTestPrinter.swift

@@ -20,61 +20,52 @@ import Foundation
 /// on an XCTest bundle but instead is an executable that queries the XCTest framework directly for
 /// the tests to run.
 struct ObjcTestPrinter {
-  /// Prints the main test runner to a Swift source file.
-  func printTestRunner(toFileAt url: URL) {
+  /// Returns the Swift source code for the test runner.
+  func testRunnerSource() -> String {
     var contents = """
       import BazelTestObservation
       import Foundation
       import XCTest
 
-      @main
       \(availabilityAttribute)
-      struct Runner {
-        static func main() {
-          loadXCTest()
-          if let xmlObserver = BazelXMLTestObserver.default {
-            XCTestObservationCenter.shared.addTestObserver(xmlObserver)
-          }
-          do {
-            var testCollector = try ShardingFilteringTestCollector()
-            let shardedSuite = testCollector.shard(XCTestSuite.default)
-            shardedSuite.run()
-            if let testRun = shardedSuite.testRun {
-              exit(testRun.totalFailureCount == 0 ? EXIT_SUCCESS : EXIT_FAILURE)
-            }
-          } catch {
-            print("ERROR: \\(error); exiting.")
-            exit(1)
-          }
+      @MainActor
+      struct XCTestRunner {
+        struct Error: Swift.Error, CustomStringConvertible {
+          let description: String
         }
-      }
 
-      private func loadXCTest() {
-        // We weakly linked to XCTest.framework and the Swift support dylib because the machine
-        // that links the test binary might not be the same that runs it, and they might have Xcode
-        // installed at different paths. Find the path that Bazel says they're installed at on
-        // *this* machine and load them.
-        guard let sdkRoot = ProcessInfo.processInfo.environment["SDKROOT"] else {
-          print("ERROR: Bazel must set the SDKROOT in order to find XCTest")
-          exit(1)
-        }
-        let sdkRootURL = URL(fileURLWithPath: sdkRoot)
-        let platformDeveloperPath = sdkRootURL  // .../Developer/SDKs/MacOSX.sdk
-          .deletingLastPathComponent()  // .../Developer/SDKs
-          .deletingLastPathComponent()  // .../Developer
-        let xcTestPath = platformDeveloperPath
-          .appendingPathComponent("Library/Frameworks/XCTest.framework/XCTest")
-          .path
-        guard dlopen(xcTestPath, RTLD_NOW) != nil else {
-          print("ERROR: dlopen(\\"\\(xcTestPath)\\") failed")
-          exit(1)
+        static func run() throws {
+          try loadXCTest()
+          XCTestObservationCenter.shared.addTestObserver(BazelXMLTestObserver.default)
+          var testCollector = try ShardingFilteringTestCollector()
+          let shardedSuite = testCollector.shard(XCTestSuite.default)
+          shardedSuite.run()
         }
-        let xcTestSwiftSupportPath = platformDeveloperPath
-          .appendingPathComponent("usr/lib/libXCTestSwiftSupport.dylib")
-          .path
-        guard dlopen(xcTestSwiftSupportPath, RTLD_NOW) != nil else {
-          print("ERROR: dlopen(\\"\\(xcTestSwiftSupportPath)\\") failed")
-          exit(1)
+
+        private static func loadXCTest() throws {
+          // We weakly linked to XCTest.framework and the Swift support dylib because the machine
+          // that links the test binary might not be the same that runs it, and they might have Xcode
+          // installed at different paths. Find the path that Bazel says they're installed at on
+          // *this* machine and load them.
+          guard let sdkRoot = ProcessInfo.processInfo.environment["SDKROOT"] else {
+            throw Error(description: "ERROR: Bazel must set the SDKROOT in order to find XCTest")
+          }
+          let sdkRootURL = URL(fileURLWithPath: sdkRoot)
+          let platformDeveloperPath = sdkRootURL  // .../Developer/SDKs/MacOSX.sdk
+            .deletingLastPathComponent()  // .../Developer/SDKs
+            .deletingLastPathComponent()  // .../Developer
+          let xcTestPath = platformDeveloperPath
+            .appendingPathComponent("Library/Frameworks/XCTest.framework/XCTest")
+            .path
+          guard dlopen(xcTestPath, RTLD_NOW) != nil else {
+            throw Error(description: "ERROR: dlopen(\\"\\(xcTestPath)\\") failed")
+          }
+          let xcTestSwiftSupportPath = platformDeveloperPath
+            .appendingPathComponent("usr/lib/libXCTestSwiftSupport.dylib")
+            .path
+          guard dlopen(xcTestSwiftSupportPath, RTLD_NOW) != nil else {
+            throw Error(description: "ERROR: dlopen(\\"\\(xcTestSwiftSupportPath)\\") failed")
+          }
         }
       }
 
@@ -125,7 +116,6 @@ struct ObjcTestPrinter {
       }
 
       """
-
-    createTextFile(at: url, contents: contents)
+    return contents
   }
 }

tools/test_discoverer/SymbolGraphTestPrinter.swift

@@ -119,31 +119,34 @@ struct SymbolGraphTestPrinter {
     createTextFile(at: url, contents: contents)
   }
 
-  /// Prints the main test runner to a Swift source file.
-  func printTestRunner(toFileAt url: URL) {
+  /// Returns the Swift source code for the test runner.
+  func testRunnerSource() -> String {
     guard !discoveredTests.modules.isEmpty else {
       // If no tests were discovered, the user likely wrote non-XCTest-style tests that pass or fail
       // based on the exit code of the process. Generate an empty source file here, which will be
       // harmlessly compiled as an empty module, and the user's `main` from their own sources will
       // be used instead.
-      createTextFile(at: url, contents: "// No tests discovered; this is intentionally empty.\n")
-      return
+      return """
+        @MainActor
+        struct XCTestRunner {
+          static func run() {
+            // No XCTest-based tests discovered; this is intentionally empty.
+          }
+        }
+        """
     }
 
     var contents = """
       import BazelTestObservation
       import Foundation
       import XCTest
 
-      @main
       \(availabilityAttribute)
-      struct Runner {
-        static func main() {
-          if let xmlObserver = BazelXMLTestObserver.default {
-            XCTestObservationCenter.shared.addTestObserver(xmlObserver)
-          }
-          do {
-            var testCollector = try ShardingFilteringTestCollector()
+      @MainActor
+      struct XCTestRunner {
+        static func run() throws {
+          XCTestObservationCenter.shared.addTestObserver(BazelXMLTestObserver.default)
+          var testCollector = try ShardingFilteringTestCollector()
 
       """
 
@@ -158,11 +161,9 @@ struct SymbolGraphTestPrinter {
     // We don't pass the test filter as an argument because we've already filtered the tests in the
     // collector; this lets us do better filtering (i.e., regexes) than XCTest itself allows.
     contents += """
-            XCTMain(testCollector.testsToRun)
-          } catch {
-            print("ERROR: \\(error); exiting.")
-            exit(1)
-          }
+          // The preferred overload is one that calls `exit`, which we don't want because we have
+          // post-work to do, so force the one that returns an exit code instead.
+          let _: CInt = XCTMain(testCollector.testsToRun)
         }
       }
 
@@ -219,6 +220,6 @@ struct SymbolGraphTestPrinter {
 
       """
 
-    createTextFile(at: url, contents: contents)
+    return contents
   }
 }

tools/test_discoverer/TestDiscoverer.swift

@@ -103,11 +103,34 @@ struct TestDiscoverer: ParsableCommand {
       }
     }
 
+    var contents = """
+      import BazelTestObservation
+
+      \(availabilityAttribute)
+      @main
+      struct Main {
+        static func main() async {
+          do {
+            try XCTestRunner.run()
+
+            try XUnitTestRecorder.shared.writeXML()
+            guard !XUnitTestRecorder.shared.hasFailure else {
+              exit(1)
+            }
+          } catch {
+            print("Test runner failed with \\(error)")
+            exit(1)
+          }
+        }
+      }
+
+      """
+
     let mainFileURL = URL(fileURLWithPath: mainOutput)
     if objcTestDiscovery {
       // Print the runner source file, which implements the `@main` type that executes the tests.
       let testPrinter = ObjcTestPrinter()
-      testPrinter.printTestRunner(toFileAt: mainFileURL)
+      contents.append(testPrinter.testRunnerSource())
     } else {
       // For each module, print the list of test entries that were discovered in a source file that
       // extends that module.
@@ -116,7 +139,9 @@ struct TestDiscoverer: ParsableCommand {
         testPrinter.printTestEntries(forModule: output.moduleName, toFileAt: output.outputURL)
       }
       // Print the runner source file, which implements the `@main` type that executes the tests.
-      testPrinter.printTestRunner(toFileAt: mainFileURL)
+      contents.append(testPrinter.testRunnerSource())
     }
+
+    createTextFile(at: mainFileURL, contents: contents)
   }
 }

tools/test_observer/BUILD

@@ -9,7 +9,9 @@ swift_library(
     srcs = [
         "BazelXMLTestObserver.swift",
         "BazelXMLTestObserverRegistration.swift",
+        "Locked.swift",
         "StringInterpolation+XMLEscaping.swift",
+        "XUnitTestRecorder.swift",
     ],
     module_name = "BazelTestObservation",
     visibility = ["//visibility:public"],