[Issue #4500] Fix resource bundle accessor issue for Clang sources (#5921)

motivation: I noticed an issue when trying to access a Clang package's resources
  when testing the target from the SwiftPM CLI. In short, the resource
  bundle is placed in the same place when building a Clang-only or
  Swift-only package, but the generated resource_bundle_accessor.m's logic
  tries to create an NSBundle for a path that DNE. The difference becomes
  clear when comparing the logic to the resource_bundle_accessor.swift
  that is generated from Swift-only packages with resources.

Author: ncooke3

Fixtures/Resources/Simple/Package.swift

@@ -18,6 +18,18 @@ let package = Package(
             ]
         ),
 
+        .target(
+            name: "ClangResource",
+            resources: [
+                .copy("foo.txt"),
+            ]
+        ),
+
+        .testTarget(
+            name: "ClangResourceTests",
+            dependencies: ["ClangResource"]
+        ),
+
         .target(
             name: "CPPResource",
             resources: [

Fixtures/Resources/Simple/Sources/ClangResource/Package.m

@@ -0,0 +1,11 @@
+#import <Foundation/Foundation.h>
+
+#import "Package.h"
+
+@implementation Package
+
++ (NSBundle *)resourceBundle {
+    return SWIFTPM_MODULE_BUNDLE;
+}
+
+@end

Fixtures/Resources/Simple/Sources/ClangResource/foo.txt

@@ -0,0 +1 @@
+

Fixtures/Resources/Simple/Sources/ClangResource/include/Package.h

@@ -0,0 +1,7 @@
+#import <Foundation/Foundation.h>
+
+@interface Package : NSObject
+
++ (NSBundle *)resourceBundle;
+
+@end

Fixtures/Resources/Simple/Tests/ClangResourceTests/ClangResourceTests.m

@@ -0,0 +1,14 @@
+#import <XCTest/XCTest.h>
+
+@import ClangResource;
+
+@interface ClangResourceTests : XCTestCase
+@end
+
+@implementation ClangResourceTests
+
+- (void)testResourceBundleIsNonNil {
+    XCTAssertNotNil([Package resourceBundle]);
+}
+
+@end

Sources/Build/BuildPlan.swift

@@ -503,7 +503,13 @@ public final class ClangTargetBuildDescription {
 
         NSBundle* \(target.c99name)_SWIFTPM_MODULE_BUNDLE() {
             NSURL *bundleURL = [[[NSBundle mainBundle] bundleURL] URLByAppendingPathComponent:@"\(bundleBasename)"];
-            return [NSBundle bundleWithURL:bundleURL];
+
+            NSBundle *preferredBundle = [NSBundle bundleWithURL:bundleURL];
+            if (preferredBundle == nil) {
+              return [NSBundle bundleWithPath:@"\(bundlePath.pathString)"];
+            }
+
+            return preferredBundle;
         }
         """
 

Sources/SPMTestSupport/XCTAssertHelpers.swift

@@ -56,12 +56,25 @@ public func XCTAssertBuilds(
 
 public func XCTAssertSwiftTest(
     _ path: AbsolutePath,
+    configuration: Configuration = .Debug,
+    extraArgs: [String] = [],
+    Xcc: [String] = [],
+    Xld: [String] = [],
+    Xswiftc: [String] = [],
     env: EnvironmentVariables? = nil,
     file: StaticString = #file,
     line: UInt = #line
 ) {
     XCTAssertNoThrow(
-        try SwiftPMProduct.SwiftTest.execute([], packagePath: path, env: env),
+        try executeSwiftTest(
+            path,
+            configuration: configuration,
+            extraArgs: extraArgs,
+            Xcc: Xcc,
+            Xld: Xld,
+            Xswiftc: Xswiftc,
+            env: env
+        ),
         file: file,
         line: line
     )

Tests/FunctionalTests/ResourcesTests.swift

@@ -102,4 +102,15 @@ class ResourcesTests: XCTestCase {
             #endif
         }
     }
+
+    func testResourceBundleInClangPackageWhenRunningSwiftTest() throws {
+        #if !os(macOS)
+        // Running swift-test fixtures on linux is not yet possible.
+        try XCTSkipIf(true, "test is only supported on macOS")
+        #endif
+
+        try fixture(name: "Resources/Simple") { fixturePath in
+            XCTAssertSwiftTest(fixturePath, extraArgs: ["--filter", "ClangResourceTests"])
+        }
+    }
 }