fix(async-rewriter2): ensure sort without compare fn works MONGOSH-676 (#773)

Author: addaleax

packages/async-rewriter2/src/async-writer-babel.spec.ts

@@ -674,6 +674,14 @@ describe('AsyncWriter', () => {
         `);
         expect(arr).to.deep.equal(new Uint8Array([1, 4, 9, 16]));
       });
+
+      it('supports Array.prototype.sort without callback', () => {
+        const arr = runTranspiledCode(`
+          const arr = [ 1, 9, 4, 16 ];
+          arr.sort()
+        `);
+        expect(arr).to.deep.equal([ 1, 16, 4, 9 ]);
+      });
     });
 
     context('Function.prototype.toString', () => {

packages/async-rewriter2/src/runtime-support.nocov.js

@@ -453,23 +453,23 @@ module.exports = '(' + function() {
 
   const origArraySort = Array.prototype.sort;
   Array.prototype.sort = function(compareFn) {
-    return origArraySort.call(this, function(...args) {
+    return origArraySort.call(this, compareFn ? function(...args) {
       // (Ab-)use a generator function as one of the places where using
       // implicit async expression results in an error.
       return [...(function*() {
         yield compareFn(...args);
       })()][0];
-    });
+    } : undefined);
   };
   const origTypedArraySort = TypedArray.prototype.sort;
   TypedArray.prototype.sort = function(compareFn) {
-    return origTypedArraySort.call(this, function(...args) {
+    return origTypedArraySort.call(this, compareFn ? function(...args) {
       // (Ab-)use a generator function as one of the places where using
       // implicit async expression results in an error.
       return [...(function*() {
         yield compareFn(...args);
       })()][0];
-    });
+    } : undefined);
   };
 
   Array.prototype.flatMap = function(...args) {