chore: checkpoint before Python removal

vendor/schemars/tests/ffi.rs

@@ -0,0 +1,16 @@
+mod util;
+use schemars::JsonSchema;
+use std::ffi::{OsStr, OsString};
+use util::*;
+
+#[allow(dead_code)]
+#[derive(JsonSchema)]
+struct OsStrings {
+    owned: OsString,
+    borrowed: &'static OsStr,
+}
+
+#[test]
+fn os_strings() -> TestResult {
+    test_default_generated_schema::<OsStrings>("os_strings")
+}