feat: Add debug-only file change detection for rapid iteration

Enables --hot-reload flag to watch config files and notify on changes.
Detects modifications to assets/sequences/music for rebuild workflow.
Completely stripped from release builds (0 bytes overhead).

Co-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com>

1 files changed, 63 insertions, 0 deletions

diff --git a/src/tests/test_file_watcher.cc b/src/tests/test_file_watcher.cc
new file mode 100644
index 0000000..ac13afd
--- /dev/null
+++ b/src/tests/test_file_watcher.cc
@@ -0,0 +1,63 @@
+// test_file_watcher.cc - Unit tests for file change detection
+
+#include "util/file_watcher.h"
+#include <cstdio>
+#include <fstream>
+#include <unistd.h>
+
+#if !defined(STRIP_ALL)
+
+int main() {
+  // Create a temporary test file
+  const char* test_file = "/tmp/test_watcher_file.txt";
+  {
+    std::ofstream f(test_file);
+    f << "initial content\n";
+  }
+
+  FileWatcher watcher;
+  watcher.add_file(test_file);
+
+  // Initial check - no changes yet
+  bool changed = watcher.check_changes();
+  if (changed) {
+    fprintf(stderr, "FAIL: Expected no changes on first check\n");
+    return 1;
+  }
+
+  // Sleep to ensure mtime changes (some filesystems have 1s granularity)
+  sleep(1);
+
+  // Modify the file
+  {
+    std::ofstream f(test_file, std::ios::app);
+    f << "modified\n";
+  }
+
+  // Check for changes
+  changed = watcher.check_changes();
+  if (!changed) {
+    fprintf(stderr, "FAIL: Expected changes after file modification\n");
+    return 1;
+  }
+
+  // Reset and check again - should be no changes
+  watcher.reset();
+  changed = watcher.check_changes();
+  if (changed) {
+    fprintf(stderr, "FAIL: Expected no changes after reset\n");
+    return 1;
+  }
+
+  printf("PASS: FileWatcher tests\n");
+  return 0;
+}
+
+#else
+
+int main() {
+  printf("SKIP: FileWatcher tests (STRIP_ALL build)\n");
+  return 0;
+}
+
+#endif