test: fix race condition in addon test

PR-URL: https://github.com/nodejs/node/pull/16037
Reviewed-By: Joyee Cheung <joyeec9h3@gmail.com>
Reviewed-By: Evan Lucas <evanlucas@me.com>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: Refael Ackermann <refack@gmail.com>

test/addons-napi/test_promise/test.js

@@ -4,32 +4,34 @@ const common = require('../../common');
 const test_promise = require(`./build/${common.buildType}/test_promise`);
 const assert = require('assert');
 
-let expected_result, promise;
-
 // A resolution
-expected_result = 42;
-promise = test_promise.createPromise();
-promise.then(
-  common.mustCall(function(result) {
-    assert.strictEqual(result, expected_result,
-                       'promise resolved as expected');
-  }),
-  common.mustNotCall());
-test_promise.concludeCurrentPromise(expected_result, true);
+{
+  const expected_result = 42;
+  const promise = test_promise.createPromise();
+  promise.then(
+    common.mustCall(function(result) {
+      assert.strictEqual(result, expected_result,
+                         `promise resolved as expected, received ${result}`);
+    }),
+    common.mustNotCall());
+  test_promise.concludeCurrentPromise(expected_result, true);
+}
 
 // A rejection
-expected_result = 'It\'s not you, it\'s me.';
-promise = test_promise.createPromise();
-promise.then(
-  common.mustNotCall(),
-  common.mustCall(function(result) {
-    assert.strictEqual(result, expected_result,
-                       'promise rejected as expected');
-  }));
-test_promise.concludeCurrentPromise(expected_result, false);
+{
+  const expected_result = 'It\'s not you, it\'s me.';
+  const promise = test_promise.createPromise();
+  promise.then(
+    common.mustNotCall(),
+    common.mustCall(function(result) {
+      assert.strictEqual(result, expected_result,
+                         `promise rejected as expected, received ${result}`);
+    }));
+  test_promise.concludeCurrentPromise(expected_result, false);
+}
 
 // Chaining
-promise = test_promise.createPromise();
+const promise = test_promise.createPromise();
 promise.then(
   common.mustCall(function(result) {
     assert.strictEqual(result, 'chained answer',
@@ -38,23 +40,10 @@ promise.then(
   common.mustNotCall());
 test_promise.concludeCurrentPromise(Promise.resolve('chained answer'), true);
 
-assert.strictEqual(test_promise.isPromise(promise), true,
-                   'natively created promise is recognized as a promise');
-
-assert.strictEqual(test_promise.isPromise(Promise.reject(-1)), true,
-                   'Promise created with JS is recognized as a promise');
-
-assert.strictEqual(test_promise.isPromise(2.4), false,
-                   'Number is recognized as not a promise');
-
-assert.strictEqual(test_promise.isPromise('I promise!'), false,
-                   'String is recognized as not a promise');
-
-assert.strictEqual(test_promise.isPromise(undefined), false,
-                   'undefined is recognized as not a promise');
-
-assert.strictEqual(test_promise.isPromise(null), false,
-                   'null is recognized as not a promise');
-
-assert.strictEqual(test_promise.isPromise({}), false,
-                   'an object is recognized as not a promise');
+assert.strictEqual(test_promise.isPromise(promise), true);
+assert.strictEqual(test_promise.isPromise(Promise.reject(-1)), true);
+assert.strictEqual(test_promise.isPromise(2.4), false);
+assert.strictEqual(test_promise.isPromise('I promise!'), false);
+assert.strictEqual(test_promise.isPromise(undefined), false);
+assert.strictEqual(test_promise.isPromise(null), false);
+assert.strictEqual(test_promise.isPromise({}), false);