test(ffi): add mutable buffer tests (#12701)

2 files changed, 25 insertions, 0 deletions

diff --git a/test_ffi/src/lib.rs b/test_ffi/src/lib.rs
index d7fd5182d..38275e547 100644
--- a/test_ffi/src/lib.rs
+++ b/test_ffi/src/lib.rs
@@ -76,6 +76,15 @@ pub extern "C" fn sleep_blocking(ms: u64) {
 
 #[allow(clippy::not_unsafe_ptr_arg_deref)]
 #[no_mangle]
+pub extern "C" fn fill_buffer(value: u8, buf: *mut u8, len: usize) {
+  let buf = unsafe { std::slice::from_raw_parts_mut(buf, len) };
+  for itm in buf.iter_mut() {
+    *itm = value;
+  }
+}
+
+#[allow(clippy::not_unsafe_ptr_arg_deref)]
+#[no_mangle]
 pub extern "C" fn nonblocking_buffer(ptr: *const u8, len: usize) {
   let buf = unsafe { std::slice::from_raw_parts(ptr, len) };
   assert_eq!(buf, vec![1, 2, 3, 4, 5, 6, 7, 8]);
diff --git a/test_ffi/tests/test.js b/test_ffi/tests/test.js
index fbd023a91..35d51c006 100644
--- a/test_ffi/tests/test.js
+++ b/test_ffi/tests/test.js
@@ -33,6 +33,7 @@ const dylib = Deno.dlopen(libPath, {
   "add_isize": { parameters: ["isize", "isize"], result: "isize" },
   "add_f32": { parameters: ["f32", "f32"], result: "f32" },
   "add_f64": { parameters: ["f64", "f64"], result: "f64" },
+  "fill_buffer": { parameters: ["u8", "buffer", "usize"], result: "void" },
   "sleep_blocking": { parameters: ["u64"], result: "void", nonblocking: true },
   "nonblocking_buffer": {
     parameters: ["buffer", "usize"],
@@ -55,6 +56,21 @@ console.log(dylib.symbols.add_isize(123, 456));
 console.log(dylib.symbols.add_f32(123.123, 456.789));
 console.log(dylib.symbols.add_f64(123.123, 456.789));
 
+// test mutating sync calls
+
+function test_fill_buffer(fillValue, arr) {
+  let buf = new Uint8Array(arr);
+  dylib.symbols.fill_buffer(fillValue, buf, buf.length);
+  for (let i = 0; i < buf.length; i++) {
+    if (buf[i] !== fillValue) {
+      throw new Error(`Found '${buf[i]}' in buffer, expected '${fillValue}'.`);
+    }
+  }
+}
+
+test_fill_buffer(0, [2, 3, 4]);
+test_fill_buffer(5, [2, 7, 3, 2, 1]);
+
 // Test non blocking calls
 
 function deferred() {