Update test: expect individual file paths instead of directory names in exceptions

Xcode does not recursively exclude directory contents from
membershipExceptions, so the correct behavior is to list individual
files rather than directory names.

Co-Authored-By: Claude Opus 4.6 <[email protected]>

Author: AlexNsbmr

Tests/XcodeGenKitTests/SourceGeneratorTests.swift

@@ -415,7 +415,7 @@ class SourceGeneratorTests: XCTestCase {
                 try expect(exceptions.contains("Nested/b.swift")) == false
             }
 
-            $0.it("excludes entire subdirectory as single exception when no files in it are included") {
+            $0.it("excludes individual files in subdirectory when no files in it are included") {
                 let directories = """
                 Sources:
                   - a.swift
@@ -436,10 +436,11 @@ class SourceGeneratorTests: XCTestCase {
                 let exceptionSet = try unwrap(syncedFolder.exceptions?.first as? PBXFileSystemSynchronizedBuildFileExceptionSet)
                 let exceptions = try unwrap(exceptionSet.membershipExceptions)
 
-                // The whole directory should be a single exception entry, not each file within it
-                try expect(exceptions.contains("ExcludedDir")) == true
-                try expect(exceptions.contains("ExcludedDir/x.swift")) == false
-                try expect(exceptions.contains("ExcludedDir/y.swift")) == false
+                // Xcode does not recursively exclude directory contents from membershipExceptions,
+                // so individual files must be listed instead of the directory name
+                try expect(exceptions.contains("ExcludedDir")) == false
+                try expect(exceptions.contains("ExcludedDir/x.swift")) == true
+                try expect(exceptions.contains("ExcludedDir/y.swift")) == true
                 try expect(exceptions.contains("a.swift")) == false
             }