wantLastMod      string
		wantContentType  string
		wantContentRange string
		wantStatus       int
	}
	htmlModTime := mustStat(t, "testdata/index.html").ModTime()
	tests := map[string]testCase{
		"no_last_modified": {
			file:            "testdata/style.css",
			wantContentType: "text/css; charset=utf-8",
			wantStatus:      200,
		},
		"with_last_modified": {
			file:            "testdata/index.html",