2 files changed, 28 insertions, 1 deletions

diff --git a/src/mainwindow.cpp b/src/mainwindow.cpp
index 7c7b801..75549d3 100644
--- a/src/mainwindow.cpp
+++ b/src/mainwindow.cpp
@@ -83,6 +83,21 @@ QString MainWindow::uiStatePath()
     return base + QStringLiteral("/qtmaildir/uistate.conf");
 }
 
+namespace {
+/// Overridden only by setLocksPathForTesting(); "/proc/locks" in every real run.
+QString g_locksPath = QStringLiteral("/proc/locks");
+} // namespace
+
+void MainWindow::setLocksPathForTesting(const QString &path)
+{
+    g_locksPath = path;
+}
+
+QString MainWindow::locksPath()
+{
+    return g_locksPath;
+}
+
 void MainWindow::restoreUiState()
 {
     QSettings state(uiStatePath(), QSettings::IniFormat);
@@ -465,7 +480,7 @@ void MainWindow::buildUi()
     // every ten minutes, so mail arrives and tags change while the window sits
     // idle, and until now nothing here noticed.
     m_syncMonitor = new SyncMonitor(SyncMonitor::defaultLockPath(),
-                                    QStringLiteral("/proc/locks"), this);
+                                    locksPath(), this);
     connect(m_syncMonitor, &SyncMonitor::stateChanged,
             this, &MainWindow::onExternalSyncStateChanged);
     m_syncMonitor->start();
diff --git a/src/mainwindow.h b/src/mainwindow.h
index 22c8187..96b27f4 100644
--- a/src/mainwindow.h
+++ b/src/mainwindow.h
@@ -104,6 +104,18 @@ public:
     /// preserve comments or key order).
     static QString uiStatePath();
 
+    /// Kernel lock table every MainWindow's SyncMonitor watches, "/proc/locks"
+    /// unless a test overrides it.
+    ///
+    /// A test seam, deliberately NOT a config key: /proc/locks is not something
+    /// a user would ever set, and a wrong value silently disables background
+    /// sync detection rather than failing loudly. Without this every window a
+    /// test builds observes the machine's real sync state, so a test asserting
+    /// on the sync button fails whenever the user's cron sync happens to be
+    /// running (item 38).
+    static void setLocksPathForTesting(const QString &path);
+    static QString locksPath();
+
 protected:
     void closeEvent(QCloseEvent *event) override;