Implement functional tests for i32 polyfills

Author: Mauro Bringolf

packages/proposal-sign-extension-ops/package.json

@@ -29,6 +29,7 @@
     "@webassemblyjs/helper-test-framework": "1.5.6",
     "@webassemblyjs/wast-parser": "1.5.6",
     "@webassemblyjs/wasm-parser": "1.5.6",
-    "@webassemblyjs/wast-printer": "1.5.6"
+    "@webassemblyjs/wast-printer": "1.5.6",
+    "wabt": "1.0.0"
   }
 }

packages/proposal-sign-extension-ops/test/exec.js

@@ -0,0 +1,54 @@
+const path = require("path");
+const wabt = require("wabt");
+const assert = require("assert");
+
+const { readFileSync } = require("fs");
+
+const polyfills = [
+  {
+    name: "i32_extend8_s",
+    fixtures: [
+      [0, 0],
+      [0x7f, 127],
+      [0x80, -128],
+      [0xff, -1],
+      [0x01234500, 0],
+      [0xfedcba80, -0x80],
+      [-1, -1]
+    ]
+  },
+  {
+    name: "i32_extend16_s",
+    fixtures: [
+      [0, 0],
+      [0x7fff, 32767],
+      [0x8000, -32768],
+      [0xffff, -1],
+      [0x01230000, 0],
+      [0xfedc8000, -0x8000],
+      [-1, -1]
+    ]
+  }
+];
+
+polyfills.forEach(p => {
+  p.path = path.join(__dirname, `../lib/polyfills/${p.name}.wast`);
+});
+
+polyfills.forEach(polyfill => {
+  describe(polyfill.path, () => {
+    const wast = readFileSync(polyfill.path, "utf8").trim();
+    const wasm = wabt
+      .parseWat(polyfill.path, wast)
+      .toBinary({ write_debug_names: false });
+
+    it("should return correct values", () => {
+      return WebAssembly.instantiate(wasm.buffer).then(result => {
+        const polyfillFn = result.instance.exports[polyfill.name];
+        polyfill.fixtures.forEach(([input, output]) => {
+          assert.equal(output, polyfillFn(input));
+        });
+      });
+    });
+  });
+});