Escape some symbols in external args (#1687)

* Escape some symbols in external args

* Don't escape on Windows, which does its own

* fix warning

tests/shell/pipeline/commands/external.rs

@@ -48,6 +48,20 @@ fn automatically_change_directory_with_trailing_slash_and_same_name_as_command()
     })
 }
 
+// #[test]
+// fn correctly_escape_external_arguments() {
+//     let actual = nu!(cwd: ".", r#"^echo '[{"foo": "bar"}]' | from-json | to-json"#);
+
+//     assert_eq!(actual, "{\"foo\":\"bar\"}");
+// }
+
+#[test]
+fn correctly_escape_external_arguments() {
+    let actual = nu!(cwd: ".", r#"^echo '$0'"#);
+
+    assert_eq!(actual, "$0");
+}
+
 mod it_evaluation {
     use super::nu;
     use nu_test_support::fs::Stub::{EmptyFile, FileWithContent, FileWithContentToBeTrimmed};