db: update FernDB

Add `mutex` field to the FernDB struct.

1 files changed, 16 insertions, 0 deletions

diff --git a/db/db_test.go b/db/db_test.go
index 5a2a983..e2308c1 100644
--- a/db/db_test.go
+++ b/db/db_test.go
@@ -46,6 +46,14 @@ func TestOpenNewDB(t *testing.T) {
 		return
 	}
 
+	// Verify that 'mutex' is initialized.
+	if db.mutex == nil {
+		t.Errorf("db.mutex is nil")
+		return
+	}
+	db.mutex.Lock()
+	db.mutex.Unlock()
+
 	// Verify that 'downloaded' is initialized
 	if db.downloaded == nil {
 		t.Errorf("db.downloaded is nil")
@@ -77,6 +85,14 @@ func TestOpenExistingDB(t *testing.T) {
 		return
 	}
 
+	// Verify that 'mutex' is initialized.
+	if db.mutex == nil {
+		t.Errorf("db.mutex is nil")
+		return
+	}
+	db.mutex.Lock()
+	db.mutex.Unlock()
+
 	// Validate db.downloaded.
 	var entries, expectedEntries []string
 	var ok bool