Update testReadFromOtherLanguages test to also run on macos (#8044)

tests/swift/tests/Tests/FlatBuffers.Test.SwiftTests/FlatBuffersMonsterWriterTests.swift

@@ -34,10 +34,10 @@ class FlatBuffersMonsterWriterTests: XCTestCase {
   }
 
   func testReadFromOtherLanguages() {
-    let path = FileManager.default.currentDirectoryPath
     let url = URL(fileURLWithPath: path, isDirectory: true)
-      .appendingPathComponent("monsterdata_test").appendingPathExtension("mon")
-    guard let data = try? Data(contentsOf: url) else { return }
+      .appendingPathComponent("monsterdata_test")
+      .appendingPathExtension("mon")
+    let data = try! Data(contentsOf: url)
     let _data = ByteBuffer(data: data)
     readVerifiedMonster(fb: _data)
   }
@@ -469,4 +469,19 @@ class FlatBuffersMonsterWriterTests: XCTestCase {
     {\"hp\":80,\"inventory\":[0,1,2,3,4],\"test\":{\"name\":\"Fred\"},\"testarrayofstring\":[\"test1\",\"test2\"],\"testarrayoftables\":[{\"name\":\"Barney\"},{\"name\":\"Frodo\"},{\"name\":\"Wilma\"}],\"test4\":[{\"a\":30,\"b\":40},{\"a\":10,\"b\":20}],\"testbool\":true,\"test_type\":\"Monster\",\"pos\":{\"y\":2,\"test3\":{\"a\":5,\"b\":6},\"z\":3,\"x\":1,\"test1\":3,\"test2\":\"Green\"},\"name\":\"MyMonster\"}
     """
   }
+
+  private var path: String {
+    #if os(macOS)
+    // Gets the current path of this test file then
+    // strips out the nested directories.
+    let filePath = URL(filePath: #file)
+      .deletingLastPathComponent()
+      .deletingLastPathComponent()
+      .deletingLastPathComponent()
+    return filePath.absoluteString
+    #else
+    return FileManager.default.currentDirectoryPath
+    #endif
+  }
+
 }