make isPromise support null as a parameter (mochajs#3518)

TwineHealth · Dec 11, 2018 · e44b9b4 · e44b9b4
1 parent 7cfbd0d
commit e44b9b4
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Showing 2 changed files with 9 additions and 1 deletion.
diff --git a/lib/utils.js b/lib/utils.js
@@ -688,7 +688,11 @@ exports.stackTraceFilter = function() {
  * @returns {boolean} Whether or not `value` is a Promise
  */
 exports.isPromise = function isPromise(value) {
-  return typeof value === 'object' && typeof value.then === 'function';
+  return (
+    typeof value === 'object' &&
+    value !== null &&
+    typeof value.then === 'function'
+  );
 };
 
 /**

diff --git a/test/unit/utils.spec.js b/test/unit/utils.spec.js
@@ -591,6 +591,10 @@ describe('lib/utils', function() {
     it('should return false if the value is an object w/o a "then" function', function() {
       expect(utils.isPromise({}), 'to be', false);
     });
+
+    it('should return false if the object is null', function() {
+      expect(utils.isPromise(null), 'to be', false);
+    });
   });
 
   describe('escape', function() {