types: fix path handling in node key tests (#7493)

These tests use a deterministic and unseeded random source to generate
non-colliding filenames for testing. When testing locally, this means tests are
not hermetic from one run to the next.

Use proper temp directories, and clean up after they're done.

types/node_key_test.go

@@ -7,12 +7,11 @@ import (
 
 	"github.com/stretchr/testify/require"
 
-	tmrand "github.com/tendermint/tendermint/libs/rand"
 	"github.com/tendermint/tendermint/types"
 )
 
 func TestLoadOrGenNodeKey(t *testing.T) {
-	filePath := filepath.Join(os.TempDir(), tmrand.Str(12)+"_peer_id.json")
+	filePath := filepath.Join(t.TempDir(), "peer_id.json")
 
 	nodeKey, err := types.LoadOrGenNodeKey(filePath)
 	require.Nil(t, err)
@@ -23,7 +22,7 @@ func TestLoadOrGenNodeKey(t *testing.T) {
 }
 
 func TestLoadNodeKey(t *testing.T) {
-	filePath := filepath.Join(os.TempDir(), tmrand.Str(12)+"_peer_id.json")
+	filePath := filepath.Join(t.TempDir(), "peer_id.json")
 
 	_, err := types.LoadNodeKey(filePath)
 	require.True(t, os.IsNotExist(err))
@@ -37,7 +36,7 @@ func TestLoadNodeKey(t *testing.T) {
 }
 
 func TestNodeKeySaveAs(t *testing.T) {
-	filePath := filepath.Join(os.TempDir(), tmrand.Str(12)+"_peer_id.json")
+	filePath := filepath.Join(t.TempDir(), "peer_id.json")
 	require.NoFileExists(t, filePath)
 
 	nodeKey := types.GenNodeKey()