diff --git a/docstore/drivertest/driverbenchmark.go b/docstore/drivertest/driverbenchmark.go
index ed3e23b1f0..4e6f5a5d3d 100644
--- a/docstore/drivertest/driverbenchmark.go
+++ b/docstore/drivertest/driverbenchmark.go
@@ -27,7 +27,7 @@ import (
 // RunBenchmarks runs benchmarks for docstore drivers.
 func RunBenchmarks(b *testing.B, coll *docstore.Collection) {
 	defer coll.Close()
-	clearCollection(b, coll)
+	ClearCollection(b, coll)
 	b.Run("BenchmarkSingleActionPut", func(b *testing.B) {
 		benchmarkSingleActionPut(10, b, coll)
 	})
@@ -40,7 +40,7 @@ func RunBenchmarks(b *testing.B, coll *docstore.Collection) {
 	b.Run("BenchmarkActionListGet", func(b *testing.B) {
 		benchmarkActionListGet(100, b, coll)
 	})
-	clearCollection(b, coll)
+	ClearCollection(b, coll)
 }
 
 func benchmarkSingleActionPut(n int, b *testing.B, coll *docstore.Collection) {
diff --git a/docstore/drivertest/drivertest.go b/docstore/drivertest/drivertest.go
index 39aaaed5cd..4a5305d235 100644
--- a/docstore/drivertest/drivertest.go
+++ b/docstore/drivertest/drivertest.go
@@ -249,7 +249,7 @@ func withColl(t *testing.T, h Harness, kind CollectionKind, f func(*testing.T, H
 	}
 	coll := docstore.NewCollection(dc)
 	defer coll.Close()
-	clearCollection(t, coll)
+	ClearCollection(t, coll)
 	f(t, h, coll)
 }
 
@@ -1541,8 +1541,8 @@ func filterHighScores(hs []*HighScore, f func(*HighScore) bool) []*HighScore {
 	return res
 }
 
-// clearCollection delete all documents from this collection after test.
-func clearCollection(fataler interface{ Fatalf(string, ...interface{}) }, coll *docstore.Collection) {
+// ClearCollection delete all documents from this collection after test.
+func ClearCollection(fataler interface{ Fatalf(string, ...interface{}) }, coll *docstore.Collection) {
 	ctx := context.Background()
 	iter := coll.Query().Get(ctx)
 	dels := coll.Actions()
diff --git a/docstore/mongodocstore/mongo_test.go b/docstore/mongodocstore/mongo_test.go
index 2e29e1d21e..8e45d8c78d 100644
--- a/docstore/mongodocstore/mongo_test.go
+++ b/docstore/mongodocstore/mongo_test.go
@@ -236,6 +236,7 @@ func TestLowercaseFields(t *testing.T) {
 	}
 	coll := docstore.NewCollection(dc)
 	defer coll.Close()
+	defer drivertest.ClearCollection(t, coll)
 
 	type S struct {
 		ID, F, G         int