diff --git a/lib/timedbs/timedbs_test.go b/lib/timedbs/timedbs_test.go
new file mode 100644
index 000000000..75f298a1d
--- /dev/null
+++ b/lib/timedbs/timedbs_test.go
@@ -0,0 +1,78 @@
+package timedbs_test
+
+import (
+	"context"
+	"testing"
+	"time"
+
+	"github.com/stretchr/testify/require"
+
+	blocks "github.com/ipfs/go-block-format"
+	"github.com/ipfs/go-cid"
+
+	"github.com/filecoin-project/lotus/lib/timedbs"
+)
+
+func TestTimedBSSimple(t *testing.T) {
+	tc := timedbs.NewTimedCacheBS(3 * time.Millisecond)
+	_ = tc.Start(context.Background())
+	defer func() {
+		_ = tc.Stop(context.Background())
+	}()
+
+	b1 := blocks.NewBlock([]byte("foo"))
+	require.NoError(t, tc.Put(b1))
+
+	b2 := blocks.NewBlock([]byte("bar"))
+	require.NoError(t, tc.Put(b2))
+
+	b3 := blocks.NewBlock([]byte("baz"))
+
+	b1out, err := tc.Get(b1.Cid())
+	require.NoError(t, err)
+	require.Equal(t, b1.RawData(), b1out.RawData())
+
+	has, err := tc.Has(b1.Cid())
+	require.NoError(t, err)
+	require.True(t, has)
+
+	time.Sleep(4 * time.Millisecond)
+
+	// We should still have everything.
+	has, err = tc.Has(b1.Cid())
+	require.NoError(t, err)
+	require.True(t, has)
+
+	has, err = tc.Has(b2.Cid())
+	require.NoError(t, err)
+	require.True(t, has)
+
+	// extend b2, add b3.
+	require.NoError(t, tc.Put(b2))
+	require.NoError(t, tc.Put(b3))
+
+	// all keys once.
+	allKeys, err := tc.AllKeysChan(context.Background())
+	var ks []cid.Cid
+	for k := range allKeys {
+		ks = append(ks, k)
+	}
+	require.NoError(t, err)
+	require.ElementsMatch(t, ks, []cid.Cid{b1.Cid(), b2.Cid(), b3.Cid()})
+
+	time.Sleep(4 * time.Millisecond)
+
+	// should still have b2, and b3, but not b1
+
+	has, err = tc.Has(b1.Cid())
+	require.NoError(t, err)
+	require.False(t, has)
+
+	has, err = tc.Has(b2.Cid())
+	require.NoError(t, err)
+	require.True(t, has)
+
+	has, err = tc.Has(b3.Cid())
+	require.NoError(t, err)
+	require.True(t, has)
+}