1 files changed, 57 insertions, 0 deletions
diff --git a/vrsite/main_test.go b/vrsite/main_test.go
new file mode 100644
index 0000000..7e715b9
--- /dev/null
+++ b/vrsite/main_test.go
@@ -0,0 +1,57 @@
+package main
+
+import (
+	"os"
+	"path/filepath"
+	"testing"
+	"time"
+)
+
+func TestWatchLogDebouncesChanges(t *testing.T) {
+	logPath := filepath.Join(t.TempDir(), "trace.jsonl")
+	if err := os.WriteFile(logPath, []byte("initial\n"), 0o644); err != nil {
+		t.Fatal(err)
+	}
+
+	done := make(chan struct{})
+	stopped := make(chan struct{})
+	rebuilt := make(chan struct{}, 2)
+	go func() {
+		defer close(stopped)
+		watchLogUntil(logPath, 60*time.Millisecond, 5*time.Millisecond, done, func() {
+			rebuilt <- struct{}{}
+		})
+	}()
+	time.Sleep(20 * time.Millisecond)
+
+	if err := os.WriteFile(logPath, []byte("first change\n"), 0o644); err != nil {
+		t.Fatal(err)
+	}
+	time.Sleep(30 * time.Millisecond)
+	if err := os.WriteFile(logPath, []byte("second change\n"), 0o644); err != nil {
+		t.Fatal(err)
+	}
+
+	select {
+	case <-rebuilt:
+		t.Fatal("rebuilt before the debounce interval elapsed")
+	case <-time.After(40 * time.Millisecond):
+	}
+	select {
+	case <-rebuilt:
+	case <-time.After(200 * time.Millisecond):
+		t.Fatal("did not rebuild after changes settled")
+	}
+	select {
+	case <-rebuilt:
+		t.Fatal("multiple changes produced more than one rebuild")
+	case <-time.After(40 * time.Millisecond):
+	}
+
+	close(done)
+	select {
+	case <-stopped:
+	case <-time.After(time.Second):
+		t.Fatal("watcher did not stop")
+	}
+}