node.js Promises how to handle errors at the highest calling level in nested Promises

Question

I am setting up my test DB in a before() hook, using nested Promises. It runs well, but I don't know how to catch the error at the highest level ( in the before() hook) . Looking in the console.log , when an error is catched in a a nested Promise, it is returned to the previous level as a value... not matched..

group.test.js

 before(() => {
   return utils.clearCollections()
     .then(() => {
       return utils.createSuperAdmin()
         .then(() => {
           return utils.createTestGroups(3)
             .then((insertedGroups) => {
               groups = insertedGroups;
               return utils.addRolesInGroups(groups)
                 .then((insertedRoles) => {
                   console.log('DONE ! %j', insertedRoles);
                 })
                 .catch((e) => {
                   console.log('error %j', e);
               });
             });
         });
     });
 });

test.utility.js

 export function addRolesInGroups(groups) {
     ...
    return Role.insertMany([roleA1, roleA2, roleA3, roleB2, roleB3, roleC3, role4 ])
        .then((insertedRoles) => {
          console.log('Successfully created test roles in groups');
          return insertedRoles;
        })
        .catch((e) => {
          console.log('Error inserting many: %j', e);
          return e;
      });
 }

console.log

The error is corrrectly catched in the Promise function addRolesInGroups() BUT it is returned to the calling before() hook .. not catched...

Error inserting many: {"code":11000,"index":3,"errmsg":"E11000 
duplicate key error collection: cockpit-api-test.roles index: name_1 
dup key: { : \"manager\" }","op": "__v":0,
"_groupId":"5954d45e05206235d308f4d6",
"name":"manager","description":"can R group, can RW
 user","_id":"5954d45e05206235d308f4db","rolePermissions"
 [],"permissions":[{"resourceName":"group","authorizedActions"
 ["read"]},{"resourceName":"user","authorizedActions"
 ["read","write"]}],"users":[]}}

DONE ! {"code":11000,"index":3,"errmsg":"E11000 duplicate key error
collection: cockpit-api-test.roles index: name_1 
dup key: { : \"manager\" }","op"
{"__v":0,"_groupId":"5954d45e05206235d308f4d6",
"name":"manager","description":"can R group, can RW
user","_id":"5954d45e05206235d308f4db","rolePermissions":[],
"permissions":[{"resourceName":"group","authorizedActions":["read"]}
{"resourceName":"user","authorizedActions":["read","write"]}]
,"users":[]}}

You'll want to `throw e` in the `catch` handler to rethrow the error, otherwise it cannot be caught again. — Bergi, Jun 29 '17 at 11:11

score 0 · Accepted Answer · answered Jun 29 '17 at 11:11

0

It's because you don't re-throw cached error, but instead you return new Promise that resolve to cached error. Change return e; to throw e;

answered Jun 29 '17 at 11:11

ponury-kostek

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node.js Promises how to handle errors at the highest calling level in nested Promises

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