backend: pass context into every backend constructor

internal/backend/rest/rest.go

@@ -36,7 +36,7 @@ const (
 )
 
 // Open opens the REST backend with the given config.
-func Open(cfg Config, rt http.RoundTripper) (*Backend, error) {
+func Open(_ context.Context, cfg Config, rt http.RoundTripper) (*Backend, error) {
 	// use url without trailing slash for layout
 	url := cfg.URL.String()
 	if url[len(url)-1] == '/' {
@@ -55,7 +55,7 @@ func Open(cfg Config, rt http.RoundTripper) (*Backend, error) {
 
 // Create creates a new REST on server configured in config.
 func Create(ctx context.Context, cfg Config, rt http.RoundTripper) (*Backend, error) {
-	be, err := Open(cfg, rt)
+	be, err := Open(ctx, cfg, rt)
 	if err != nil {
 		return nil, err
 	}

internal/backend/rest/rest_int_test.go

@@ -117,7 +117,7 @@ func TestListAPI(t *testing.T) {
 				URL:         srvURL,
 			}
 
-			be, err := rest.Open(cfg, http.DefaultTransport)
+			be, err := rest.Open(context.TODO(), cfg, http.DefaultTransport)
 			if err != nil {
 				t.Fatal(err)
 			}

internal/backend/rest/rest_test.go

@@ -90,7 +90,7 @@ func newTestSuite(_ context.Context, t testing.TB, url *url.URL, minimalData boo
 
 		// OpenFn is a function that opens a previously created temporary repository.
 		Open: func(cfg rest.Config) (restic.Backend, error) {
-			return rest.Open(cfg, tr)
+			return rest.Open(context.TODO(), cfg, tr)
 		},
 
 		// CleanupFn removes data created during the tests.