test: cover thenables when we check for promises

Added tests that cover the issue when assert.rejects() and assert.doesNotReject() should not accept Thenables without a `catch` method or any Thenable function with `catch` and `then` methods attached. PR-URL: #24219 Reviewed-By: Ruben Bridgewater <[email protected]>

Author: szabolcsit

lib/assert.js

@@ -600,6 +600,11 @@ function checkIsPromise(obj){
 // Accept native ES6 promises and promises that are implemented in a similar
 // way. Do not accept thenables that use a function as `obj` and that have no
 // `catch` handler.
+
+// TODO: thenables are checked up until they have the correct methods,
+// but according to documentation, the `then` method should receive
+// the `fulfill` and `reject` arguments as well or it may be never resolved.
+
 returnisPromise(obj)||
 obj!==null&&typeofobj==='object'&&
 typeofobj.then==='function'&&

test/parallel/test-assert-async.js

@@ -2,12 +2,34 @@
 constcommon=require('../common');
 constassert=require('assert');
 
-// Test assert.rejects() and assert.doesNotReject() by checking their
-// expected output and by verifying that they do not work sync
-
 // Run all tests in parallel and check their outcome at the end.
 constpromises=[];
 
+// Thenable object without `catch` method,
+// shouldn't be considered as a valid Thenable
+constinvalidThenable={
+then: (fulfill,reject)=>{
+fulfill();
+},
+};
+
+// Function that returns a Thenable function,
+// a function with `catch` and `then` methods attached,
+// shouldn't be considered as a valid Thenable.
+constinvalidThenableFunc=()=>{
+functionf(){}
+
+f.then=(fulfill,reject)=>{
+fulfill();
+};
+f.catch=()=>{};
+
+returnf;
+};
+
+// Test assert.rejects() and assert.doesNotReject() by checking their
+// expected output and by verifying that they do not work sync
+
 // Check `assert.rejects`.
 {
 constrejectingFn=async()=>assert.fail();
@@ -16,9 +38,34 @@ const promises = [];
 name: 'AssertionError',
 message: 'Failed'
 };
-// `assert.rejects` accepts a function or a promise as first argument.
+
+// `assert.rejects` accepts a function or a promise
+// or a thenable as first argument.
 promises.push(assert.rejects(rejectingFn,errObj));
 promises.push(assert.rejects(rejectingFn(),errObj));
+
+constvalidRejectingThenable={
+then: (fulfill,reject)=>{
+reject({code: 'FAIL'});
+},
+catch: ()=>{}
+};
+promises.push(assert.rejects(validRejectingThenable,{code: 'FAIL'}));
+
+// `assert.rejects` should not accept thenables that
+// use a function as `obj` and that have no `catch` handler.
+promises.push(assert.rejects(
+assert.rejects(invalidThenable,{}),
+{
+code: 'ERR_INVALID_ARG_TYPE'
+})
+);
+promises.push(assert.rejects(
+assert.rejects(invalidThenableFunc,{}),
+{
+code: 'ERR_INVALID_RETURN_VALUE'
+})
+);
 }
 
 {
@@ -69,7 +116,8 @@ promises.push(assert.rejects(
 
 // Check `assert.doesNotReject`.
 {
-// `assert.doesNotReject` accepts a function or a promise as first argument.
+// `assert.doesNotReject` accepts a function or a promise
+// or a thenable as first argument.
 constpromise=assert.doesNotReject(()=>newMap(),common.mustNotCall());
 promises.push(assert.rejects(promise,{
 message: 'Expected instance of Promise to be returned '+
@@ -79,6 +127,28 @@ promises.push(assert.rejects(
 }));
 promises.push(assert.doesNotReject(async()=>{}));
 promises.push(assert.doesNotReject(Promise.resolve()));
+
+// `assert.doesNotReject` should not accept thenables that
+// use a function as `obj` and that have no `catch` handler.
+constvalidFulfillingThenable={
+then: (fulfill,reject)=>{
+fulfill();
+},
+catch: ()=>{}
+};
+promises.push(assert.doesNotReject(validFulfillingThenable));
+promises.push(assert.rejects(
+assert.doesNotReject(invalidThenable),
+{
+code: 'ERR_INVALID_ARG_TYPE'
+})
+);
+promises.push(assert.rejects(
+assert.doesNotReject(invalidThenableFunc),
+{
+code: 'ERR_INVALID_RETURN_VALUE'
+})
+);
 }
 
 {