Improve Destination.sdkPlatformFrameworkPaths()

We should not ignore errors or an empty SDK platform path since that means XCTest imports and test execution might silently fail on macOS with no indication to what the problem is. I am speculating that this may be contributing to the recent surge of tests failing by not seeing the XCTest Swift library. I am also re-enabling the disabled tests here to see if this has any practical effect, but regardless it doesn't seem reasonable to silently ignore some failure states here.

rdar://101868275

Sources/PackageModel/Destination.swift

@@ -194,21 +194,23 @@ public struct Destination: Encodable, Equatable {
         if let path = _sdkPlatformFrameworkPath {
             return path
         }
-        let platformPath = try? TSCBasic.Process.checkNonZeroExit(
+        let platformPath = try TSCBasic.Process.checkNonZeroExit(
             arguments: ["/usr/bin/xcrun", "--sdk", "macosx", "--show-sdk-platform-path"],
             environment: environment).spm_chomp()
 
-        if let platformPath = platformPath, !platformPath.isEmpty {
-            // For XCTest framework.
-            let fwk = try AbsolutePath(validating: platformPath).appending(
-                components: "Developer", "Library", "Frameworks")
+        guard !platformPath.isEmpty else {
+            throw StringError("could not determine SDK platform path")
+        }
 
-            // For XCTest Swift library.
-            let lib = try AbsolutePath(validating: platformPath).appending(
-                components: "Developer", "usr", "lib")
+        // For XCTest framework.
+        let fwk = try AbsolutePath(validating: platformPath).appending(
+            components: "Developer", "Library", "Frameworks")
 
-            _sdkPlatformFrameworkPath = (fwk, lib)
-        }
+        // For XCTest Swift library.
+        let lib = try AbsolutePath(validating: platformPath).appending(
+            components: "Developer", "usr", "lib")
+
+        _sdkPlatformFrameworkPath = (fwk, lib)
         return _sdkPlatformFrameworkPath
     }
     /// Cache storage for sdk platform path.

Sources/SPMTestSupport/Toolchain.swift

@@ -33,18 +33,6 @@ private func resolveBinDir() throws -> AbsolutePath {
 #endif
 }
 
-extension UserToolchain {
-
-#if os(macOS)
-    public var sdkPlatformFrameworksPath: AbsolutePath {
-        get throws {
-            return try Destination.sdkPlatformFrameworkPaths()!.fwk
-        }
-    }
-#endif
-
-}
-
 extension Destination {
     public static var `default`: Self {
         get throws {

Tests/CommandsTests/BuildToolTests.swift

@@ -280,8 +280,6 @@ final class BuildToolTests: CommandsTestCase {
     }
 
     func testBuildCompleteMessage() throws {
-        throw XCTSkip("This test fails to match the 'Compiling' regex; rdar://101815761")
-
         try fixture(name: "DependencyResolution/Internal/Simple") { fixturePath in
             do {
                 let result = try execute([], packagePath: fixturePath)

Tests/WorkspaceTests/InitTests.swift

@@ -266,8 +266,6 @@ class InitTests: XCTestCase {
     }
 
     func testNonC99NameExecutablePackage() throws {
-        throw XCTSkip("This test fails to find XCTAssertEqual; rdar://101868275")
-
         try withTemporaryDirectory(removeTreeOnDeinit: true) { tempDirPath in
             XCTAssertDirectoryExists(tempDirPath)
 

Tests/WorkspaceTests/WorkspaceTests.swift

@@ -4291,8 +4291,6 @@ final class WorkspaceTests: XCTestCase {
 
     // This verifies that the simplest possible loading APIs are available for package clients.
     func testSimpleAPI() throws {
-        throw XCTSkip("This test fails to find XCTAssertEqual; rdar://101868275")
-
         try testWithTemporaryDirectory { path in
             // Create a temporary package as a test case.
             let packagePath = path.appending(component: "MyPkg")