1 files changed, 76 insertions, 0 deletions
diff --git a/internal/app/duration_cache_test.go b/internal/app/duration_cache_test.go
new file mode 100644
index 0000000..3830277
--- /dev/null
+++ b/internal/app/duration_cache_test.go
@@ -0,0 +1,76 @@
+package app
+
+import (
+	"os"
+	"path/filepath"
+	"testing"
+	"time"
+)
+
+func TestDurationCacheRecordLifecycle(t *testing.T) {
+	dir := t.TempDir()
+	cachePath := filepath.Join(dir, "cache.json")
+	cache, err := loadDurationCache(cachePath)
+	if err != nil {
+		t.Fatalf("load cache: %v", err)
+	}
+	video := filepath.Join(dir, "video.mp4")
+	if err := os.WriteFile(video, []byte("x"), 0o644); err != nil {
+		t.Fatalf("write video: %v", err)
+	}
+	info, err := os.Stat(video)
+	if err != nil {
+		t.Fatalf("stat video: %v", err)
+	}
+	duration := 90 * time.Second
+	if err := cache.Record(video, info, duration); err != nil {
+		t.Fatalf("record: %v", err)
+	}
+	if err := cache.Flush(); err != nil {
+		t.Fatalf("flush: %v", err)
+	}
+	cache2, err := loadDurationCache(cachePath)
+	if err != nil {
+		t.Fatalf("reload: %v", err)
+	}
+	dur, ok := cache2.Lookup(video, info)
+	if !ok {
+		t.Fatalf("expected cached entry")
+	}
+	if dur != duration {
+		t.Fatalf("expected %v, got %v", duration, dur)
+	}
+}
+
+func TestDurationCacheInvalidatesOnChange(t *testing.T) {
+	dir := t.TempDir()
+	cache := newDurationCache(filepath.Join(dir, "cache.json"))
+	video := filepath.Join(dir, "video.mp4")
+	if err := os.WriteFile(video, []byte("x"), 0o644); err != nil {
+		t.Fatalf("write: %v", err)
+	}
+	info, _ := os.Stat(video)
+	_ = cache.Record(video, info, 30*time.Second)
+	if err := os.WriteFile(video, []byte("xx"), 0o644); err != nil {
+		t.Fatalf("rewrite: %v", err)
+	}
+	info, _ = os.Stat(video)
+	if dur, ok := cache.Lookup(video, info); ok || dur != 0 {
+		t.Fatalf("expected cache miss after change")
+	}
+}
+
+func TestLoadDurationCacheInvalidJSON(t *testing.T) {
+	dir := t.TempDir()
+	path := filepath.Join(dir, "cache.json")
+	if err := os.WriteFile(path, []byte("not json"), 0o644); err != nil {
+		t.Fatalf("write cache: %v", err)
+	}
+	cache, err := loadDurationCache(path)
+	if err == nil {
+		t.Fatalf("expected error for invalid json")
+	}
+	if len(cache.entries) != 0 {
+		t.Fatalf("expected cache to reset entries")
+	}
+}