6 files changed, 91 insertions, 1 deletions
diff --git a/core/libdeno/api.cc b/core/libdeno/api.cc
index 8a3a56156..13057aeae 100644
--- a/core/libdeno/api.cc
+++ b/core/libdeno/api.cc
@@ -117,6 +117,13 @@ void deno_init() {
     platform = v8::platform::NewDefaultPlatform();
     v8::V8::InitializePlatform(platform.get());
     v8::V8::Initialize();
+    // TODO(ry) This makes WASM compile synchronously. Eventually we should
+    // remove this to make it work asynchronously too. But that requires getting
+    // PumpMessageLoop and RunMicrotasks setup correctly.
+    // See https://github.com/denoland/deno/issues/2544
+    const char* argv[2] = {"", "--no-wasm-async-compilation"};
+    int argc = 2;
+    v8::V8::SetFlagsFromCommandLine(&argc, const_cast<char**>(argv), false);
   }
 }
 
diff --git a/core/libdeno/libdeno_test.cc b/core/libdeno/libdeno_test.cc
index 485c95bff..c2d76c876 100644
--- a/core/libdeno/libdeno_test.cc
+++ b/core/libdeno/libdeno_test.cc
@@ -159,7 +159,6 @@ TEST(LibDenoTest, CheckPromiseErrors) {
   EXPECT_EQ(deno_last_exception(d), nullptr);
   deno_execute(d, nullptr, "a.js", "CheckPromiseErrors()");
   EXPECT_EQ(nullptr, deno_last_exception(d));
-  EXPECT_EQ(deno_last_exception(d), nullptr);
   EXPECT_EQ(count, 1);
   // We caught the exception. So still no errors after calling
   // deno_check_promise_errors().
@@ -261,3 +260,23 @@ TEST(LibDenoTest, SharedAtomics) {
   EXPECT_EQ(s[2], 2);
   deno_delete(d);
 }
+
+TEST(LibDenoTest, WasmInstantiate) {
+  static int count = 0;
+  auto recv_cb = [](auto _, auto buf, auto zero_copy_buf) {
+    EXPECT_EQ(buf.data_len, 1u);
+    EXPECT_EQ(buf.data_ptr[0], 42);
+    count++;
+  };
+  Deno* d = deno_new(deno_config{0, snapshot, empty, recv_cb, nullptr});
+  EXPECT_EQ(deno_last_exception(d), nullptr);
+  deno_execute(d, nullptr, "a.js", "WasmInstantiate()");
+
+  EXPECT_EQ(nullptr, deno_last_exception(d));
+  deno_check_promise_errors(d);
+  EXPECT_EQ(nullptr, deno_last_exception(d));
+
+  EXPECT_EQ(count, 3);
+
+  deno_delete(d);
+}
diff --git a/core/libdeno/libdeno_test.js b/core/libdeno/libdeno_test.js
index 17a6343cf..006c71666 100644
--- a/core/libdeno/libdeno_test.js
+++ b/core/libdeno/libdeno_test.js
@@ -219,3 +219,37 @@ global.LibDenoPrintInvalidArgument = () => {
     assert(e.message === "Invalid Argument");
   }
 };
+
+global.WasmInstantiate = () => {
+  // The following blob can be created by taking the following s-expr and pass
+  // it through wat2wasm.
+  //    (module
+  //      (func $add (param $a i32) (param $b i32) (result i32)
+  //        local.get $a
+  //        local.get $b
+  //        i32.add)
+  //      (export "add" (func $add))
+  //    )
+  // prettier-ignore
+  const bytes = new Uint8Array([
+    0x00, 0x61, 0x73, 0x6d, 0x01, 0x00, 0x00, 0x00, 0x01, 0x07, 0x01, 0x60,
+    0x02, 0x7f, 0x7f, 0x01, 0x7f, 0x03, 0x02, 0x01, 0x00, 0x07, 0x07, 0x01,
+    0x03, 0x61, 0x64, 0x64, 0x00, 0x00, 0x0a, 0x09, 0x01, 0x07, 0x00, 0x20,
+    0x00, 0x20, 0x01, 0x6a, 0x0b
+  ]);
+
+  (async () => {
+    Deno.core.send(new Uint8Array([42]));
+
+    const wasm = await WebAssembly.instantiate(bytes);
+
+    Deno.core.send(new Uint8Array([42]));
+
+    const result = wasm.instance.exports.add(1, 3);
+    if (result != 4) {
+      throw Error("bad");
+    }
+    // To signal success, we send back a fixed buffer.
+    Deno.core.send(new Uint8Array([42]));
+  })();
+};
diff --git a/tests/wasm_async.js b/tests/wasm_async.js
new file mode 100644
index 000000000..7b521caee
--- /dev/null
+++ b/tests/wasm_async.js
@@ -0,0 +1,27 @@
+// The following blob can be created by taking the following s-expr and pass
+// it through wat2wasm.
+//    (module
+//      (func $add (param $a i32) (param $b i32) (result i32)
+//        local.get $a
+//        local.get $b
+//        i32.add)
+//      (export "add" (func $add))
+//    )
+// prettier-ignore
+const bytes = new Uint8Array([
+  0x00, 0x61, 0x73, 0x6d, 0x01, 0x00, 0x00, 0x00, 0x01, 0x07, 0x01, 0x60,
+  0x02, 0x7f, 0x7f, 0x01, 0x7f, 0x03, 0x02, 0x01, 0x00, 0x07, 0x07, 0x01,
+  0x03, 0x61, 0x64, 0x64, 0x00, 0x00, 0x0a, 0x09, 0x01, 0x07, 0x00, 0x20,
+  0x00, 0x20, 0x01, 0x6a, 0x0b
+]);
+
+async function main() {
+  let wasm = await WebAssembly.instantiate(bytes);
+  let result = wasm.instance.exports.add(1, 3);
+  console.log("1 + 3 =", result);
+  if (result != 4) {
+    throw Error("bad");
+  }
+}
+
+main();
diff --git a/tests/wasm_async.out b/tests/wasm_async.out
new file mode 100644
index 000000000..5cdf17de7
--- /dev/null
+++ b/tests/wasm_async.out
@@ -0,0 +1 @@
+1 + 3 = 4
diff --git a/tests/wasm_async.test b/tests/wasm_async.test
new file mode 100644
index 000000000..534921a96
--- /dev/null
+++ b/tests/wasm_async.test
@@ -0,0 +1,2 @@
+args: tests/wasm_async.js
+output: tests/wasm_async.out