From 206370d0ed9a3e30e5e30b2ea46363a551b5c094 Mon Sep 17 00:00:00 2001
From: Mark Villacampa <m@markvillacampa.com>
Date: Thu, 29 Feb 2024 12:32:40 +0100
Subject: [PATCH] Register test observer in main queue

Fixes a crash when calling [XCTestObservationCenter addTestObserver:] that would fail an assertion: 'Test observers can only be registered and unregistered on the main thread.'
---
 Sources/SnapshotTesting/AssertSnapshot.swift | 4 +---
 1 file changed, 1 insertion(+), 3 deletions(-)

diff --git a/Sources/SnapshotTesting/AssertSnapshot.swift b/Sources/SnapshotTesting/AssertSnapshot.swift
index 552077e49..e144f6a15 100644
--- a/Sources/SnapshotTesting/AssertSnapshot.swift
+++ b/Sources/SnapshotTesting/AssertSnapshot.swift
@@ -371,11 +371,9 @@ func sanitizePathComponent(_ string: String) -> String {
 // We need to clean counter between tests executions in order to support test-iterations.
 private class CleanCounterBetweenTestCases: NSObject, XCTestObservation {
   private static var registered = false
-  private static var registerQueue = DispatchQueue(
-    label: "co.pointfree.SnapshotTesting.testObserver")
 
   static func registerIfNeeded() {
-    registerQueue.sync {
+    DispatchQueue.main.sync {
       if !registered {
         registered = true
         XCTestObservationCenter.shared.addTestObserver(CleanCounterBetweenTestCases())