test the new API

tests/runtime/main.rs

@@ -278,7 +278,12 @@ fn tests(name: &str, dir_name: &str) -> Result<Vec<PathBuf>> {
 
             let snake = world_name.replace("-", "_");
             let mut files = Default::default();
-            let opts = wit_bindgen_cpp::Opts::default();
+            let mut opts = wit_bindgen_cpp::Opts::default();
+            if let Some(path) = path.file_name().and_then(|s| s.to_str()) {
+                if path.contains(".new.") {
+                    opts.new_api = true;
+                }
+            }
             opts.build().generate(&resolve, world, &mut files).unwrap();
 
             for (file, contents) in files.iter() {

tests/runtime/strings/wasm.new.cpp

@@ -0,0 +1,29 @@
+#include <assert.h>
+#include <strings_cpp.h>
+#include <stdlib.h>
+#include <string.h>
+#include <stdio.h>
+
+void assert_str(std::string_view str, const char* expected) {
+  size_t expected_len = strlen(expected);
+  assert(str.size() == expected_len);
+  assert(memcmp(str.data(), expected, expected_len) == 0);
+}
+
+void exports::strings::TestImports() {
+  test::strings::imports::TakeBasic(std::string_view("latin utf16"));
+
+  wit::string str2 = test::strings::imports::ReturnUnicode();
+  assert_str(str2.get_view(), "🚀🚀🚀 𠈄𓀀");
+}
+
+wit::string exports::strings::ReturnEmpty() {
+  // return a non-zero address (follows cabi_realloc logic)
+  return wit::string((char const*)1, 0);
+}
+
+// new API: Identical for guest import and export
+wit::string exports::strings::Roundtrip(std::string_view str) {
+  assert(str.size() > 0);
+  return wit::string::from_view(str);
+}