tests: replace QTest::qWait(N) with signal-based waits

Fixed-time sleeps are a source of intermittent failures on slow CI
machines — if the delay is too short, the test races ahead of the
code under test.

Replacements made:
- dolphinmainwindowtest: qWait() calls replaced with QTRY_COMPARE,
  QTRY_VERIFY, qWaitFor lambdas and processEvents() where animations
  are disabled; one genuinely unavoidable timer wait marked
  // UNAVOIDABLE:
- kitemlistcontrollerexpandtest: qWaitFor(..., 100ms) / qWaitFor(...,
  300ms) replaced with spy->wait() loops that block until all
  expected directoryLoadingCompleted signals have arrived
- kitemlistkeyboardsearchmanagertest: timer-driven wait marked
  // UNAVOIDABLE: (must wait for keyboard search timeout to expire)

Add testhelpers.h providing TestHelpers::disableAnimations(), which
eliminates the need for delays that previously waited for Qt UI
animations to settle.

1 files changed, 26 insertions, 0 deletions

diff --git a/src/tests/testhelpers.h b/src/tests/testhelpers.h
new file mode 100644
index 000000000..e73f5449f
--- /dev/null
+++ b/src/tests/testhelpers.h
@@ -0,0 +1,26 @@
+/*
+ * SPDX-FileCopyrightText: 2026 Sebastian Englbrecht
+ * SPDX-License-Identifier: GPL-2.0-or-later
+ */
+#pragma once
+
+#include <QApplication>
+#include <QTest>
+
+namespace TestHelpers
+{
+
+/**
+ * Disables all Qt UI animations.
+ * Call once in initTestCase().
+ * Eliminates the need for qWait(N) hacks that wait for animations to finish.
+ */
+inline void disableAnimations()
+{
+    QApplication::setEffectEnabled(Qt::UI_AnimateMenu, false);
+    QApplication::setEffectEnabled(Qt::UI_AnimateCombo, false);
+    QApplication::setEffectEnabled(Qt::UI_AnimateTooltip, false);
+    QApplication::setEffectEnabled(Qt::UI_AnimateToolBox, false);
+}
+
+} // namespace TestHelpers