Jest: Importing module named 'constants' imports wrong object

Created on 7 Sep 2016  ·  13Comments  ·  Source: facebook/jest

If I include

import * as Constants from 'constants';

it imports this object


Constants object

{
      E2BIG: 7,
      EACCES: 13,
      EADDRINUSE: 48,
      EADDRNOTAVAIL: 49,
      EAFNOSUPPORT: 47,
      EAGAIN: 35,
      EALREADY: 37,
      EBADF: 9,
      EBADMSG: 94,
      EBUSY: 16,
      ECANCELED: 89,
      ECHILD: 10,
      ECONNABORTED: 53,
      ECONNREFUSED: 61,
      ECONNRESET: 54,
      EDEADLK: 11,
      EDESTADDRREQ: 39,
      EDOM: 33,
      EDQUOT: 69,
      EEXIST: 17,
      EFAULT: 14,
      EFBIG: 27,
      EHOSTUNREACH: 65,
      EIDRM: 90,
      EILSEQ: 92,
      EINPROGRESS: 36,
      EINTR: 4,
      EINVAL: 22,
      EIO: 5,
      EISCONN: 56,
      EISDIR: 21,
      ELOOP: 62,
      EMFILE: 24,
      EMLINK: 31,
      EMSGSIZE: 40,
      EMULTIHOP: 95,
      ENAMETOOLONG: 63,
      ENETDOWN: 50,
      ENETRESET: 52,
      ENETUNREACH: 51,
      ENFILE: 23,
      ENOBUFS: 55,
      ENODATA: 96,
      ENODEV: 19,
      ENOENT: 2,
      ENOEXEC: 8,
      ENOLCK: 77,
      ENOLINK: 97,
      ENOMEM: 12,
      ENOMSG: 91,
      ENOPROTOOPT: 42,
      ENOSPC: 28,
      ENOSR: 98,
      ENOSTR: 99,
      ENOSYS: 78,
      ENOTCONN: 57,
      ENOTDIR: 20,
      ENOTEMPTY: 66,
      ENOTSOCK: 38,
      ENOTSUP: 45,
      ENOTTY: 25,
      ENXIO: 6,
      EOPNOTSUPP: 102,
      EOVERFLOW: 84,
      EPERM: 1,
      EPIPE: 32,
      EPROTO: 100,
      EPROTONOSUPPORT: 43,
      EPROTOTYPE: 41,
      ERANGE: 34,
      EROFS: 30,
      ESPIPE: 29,
      ESRCH: 3,
      ESTALE: 70,
      ETIME: 101,
      ETIMEDOUT: 60,
      ETXTBSY: 26,
      EWOULDBLOCK: 35,
      EXDEV: 18,
      SIGHUP: 1,
      SIGINT: 2,
      SIGQUIT: 3,
      SIGILL: 4,
      SIGTRAP: 5,
      SIGABRT: 6,
      SIGIOT: 6,
      SIGBUS: 10,
      SIGFPE: 8,
      SIGKILL: 9,
      SIGUSR1: 30,
      SIGSEGV: 11,
      SIGUSR2: 31,
      SIGPIPE: 13,
      SIGALRM: 14,
      SIGTERM: 15,
      SIGCHLD: 20,
      SIGCONT: 19,
      SIGSTOP: 17,
      SIGTSTP: 18,
      SIGTTIN: 21,
      SIGTTOU: 22,
      SIGURG: 16,
      SIGXCPU: 24,
      SIGXFSZ: 25,
      SIGVTALRM: 26,
      SIGPROF: 27,
      SIGWINCH: 28,
      SIGIO: 23,
      SIGSYS: 12,
      SSL_OP_ALL: 2147486719,
      SSL_OP_ALLOW_UNSAFE_LEGACY_RENEGOTIATION: 262144,
      SSL_OP_CIPHER_SERVER_PREFERENCE: 4194304,
      SSL_OP_CISCO_ANYCONNECT: 32768,
      SSL_OP_COOKIE_EXCHANGE: 8192,
      SSL_OP_CRYPTOPRO_TLSEXT_BUG: 2147483648,
      SSL_OP_DONT_INSERT_EMPTY_FRAGMENTS: 2048,
      SSL_OP_EPHEMERAL_RSA: 0,
      SSL_OP_LEGACY_SERVER_CONNECT: 4,
      SSL_OP_MICROSOFT_BIG_SSLV3_BUFFER: 32,
      SSL_OP_MICROSOFT_SESS_ID_BUG: 1,
      SSL_OP_MSIE_SSLV2_RSA_PADDING: 0,
      SSL_OP_NETSCAPE_CA_DN_BUG: 536870912,
      SSL_OP_NETSCAPE_CHALLENGE_BUG: 2,
      SSL_OP_NETSCAPE_DEMO_CIPHER_CHANGE_BUG: 1073741824,
      SSL_OP_NETSCAPE_REUSE_CIPHER_CHANGE_BUG: 8,
      SSL_OP_NO_COMPRESSION: 131072,
      SSL_OP_NO_QUERY_MTU: 4096,
      SSL_OP_NO_SESSION_RESUMPTION_ON_RENEGOTIATION: 65536,
      SSL_OP_NO_SSLv2: 16777216,
      SSL_OP_NO_SSLv3: 33554432,
      SSL_OP_NO_TICKET: 16384,
      SSL_OP_NO_TLSv1: 67108864,
      SSL_OP_NO_TLSv1_1: 268435456,
      SSL_OP_NO_TLSv1_2: 134217728,
      SSL_OP_PKCS1_CHECK_1: 0,
      SSL_OP_PKCS1_CHECK_2: 0,
      SSL_OP_SINGLE_DH_USE: 1048576,
      SSL_OP_SINGLE_ECDH_USE: 524288,
      SSL_OP_SSLEAY_080_CLIENT_DH_BUG: 128,
      SSL_OP_SSLREF2_REUSE_CERT_TYPE_BUG: 0,
      SSL_OP_TLS_BLOCK_PADDING_BUG: 512,
      SSL_OP_TLS_D5_BUG: 256,
      SSL_OP_TLS_ROLLBACK_BUG: 8388608,
      ENGINE_METHOD_DSA: 2,
      ENGINE_METHOD_DH: 4,
      ENGINE_METHOD_RAND: 8,
      ENGINE_METHOD_ECDH: 16,
      ENGINE_METHOD_ECDSA: 32,
      ENGINE_METHOD_CIPHERS: 64,
      ENGINE_METHOD_DIGESTS: 128,
      ENGINE_METHOD_STORE: 256,
      ENGINE_METHOD_PKEY_METHS: 512,
      ENGINE_METHOD_PKEY_ASN1_METHS: 1024,
      ENGINE_METHOD_ALL: 65535,
      ENGINE_METHOD_NONE: 0,
      DH_CHECK_P_NOT_SAFE_PRIME: 2,
      DH_CHECK_P_NOT_PRIME: 1,
      DH_UNABLE_TO_CHECK_GENERATOR: 4,
      DH_NOT_SUITABLE_GENERATOR: 8,
      NPN_ENABLED: 1,
      RSA_PKCS1_PADDING: 1,
      RSA_SSLV23_PADDING: 2,
      RSA_NO_PADDING: 3,
      RSA_PKCS1_OAEP_PADDING: 4,
      RSA_X931_PADDING: 5,
      RSA_PKCS1_PSS_PADDING: 6,
      POINT_CONVERSION_COMPRESSED: 2,
      POINT_CONVERSION_UNCOMPRESSED: 4,
      POINT_CONVERSION_HYBRID: 6,
      O_RDONLY: 0,
      O_WRONLY: 1,
      O_RDWR: 2,
      S_IFMT: 61440,
      S_IFREG: 32768,
      S_IFDIR: 16384,
      S_IFCHR: 8192,
      S_IFBLK: 24576,
      S_IFIFO: 4096,
      S_IFLNK: 40960,
      S_IFSOCK: 49152,
      O_CREAT: 512,
      O_EXCL: 2048,
      O_NOCTTY: 131072,
      O_TRUNC: 1024,
      O_APPEND: 8,
      O_DIRECTORY: 1048576,
      O_NOFOLLOW: 256,
      O_SYNC: 128,
      O_SYMLINK: 2097152,
      O_NONBLOCK: 4,
      S_IRWXU: 448,
      S_IRUSR: 256,
      S_IWUSR: 128,
      S_IXUSR: 64,
      S_IRWXG: 56,
      S_IRGRP: 32,
      S_IWGRP: 16,
      S_IXGRP: 8,
      S_IRWXO: 7,
      S_IROTH: 4,
      S_IWOTH: 2,
      S_IXOTH: 1,
      F_OK: 0,
      R_OK: 4,
      W_OK: 2,
      X_OK: 1,
      UV_UDP_REUSEADDR: 4,
      defaultCoreCipherList: 'ECDHE-RSA-AES128-GCM-SHA256:ECDHE-ECDSA-AES128-GCM-SHA256:ECDHE-RSA-AES256-GCM-SHA384:ECDHE-ECDSA-AES256-GCM-SHA384:DHE-RSA-AES128-GCM-SHA256:ECDHE-RSA-AES128-SHA256:DHE-RSA-AES128-SHA256:ECDHE-RSA-AES256-SHA384:DHE-RSA-AES256-SHA384:ECDHE-RSA-AES256-SHA256:DHE-RSA-AES256-SHA256:HIGH:!aNULL:!eNULL:!EXPORT:!DES:!RC4:!MD5:!PSK:!SRP:!CAMELLIA',
      defaultCipherList: 'ECDHE-RSA-AES128-GCM-SHA256:ECDHE-ECDSA-AES128-GCM-SHA256:ECDHE-RSA-AES256-GCM-SHA384:ECDHE-ECDSA-AES256-GCM-SHA384:DHE-RSA-AES128-GCM-SHA256:ECDHE-RSA-AES128-SHA256:DHE-RSA-AES128-SHA256:ECDHE-RSA-AES256-SHA384:DHE-RSA-AES256-SHA384:ECDHE-RSA-AES256-SHA256:DHE-RSA-AES256-SHA256:HIGH:!aNULL:!eNULL:!EXPORT:!DES:!RC4:!MD5:!PSK:!SRP:!CAMELLIA',
      default:
       { E2BIG: 7,
         EACCES: 13,
         EADDRINUSE: 48,
         EADDRNOTAVAIL: 49,
         EAFNOSUPPORT: 47,
         EAGAIN: 35,
         EALREADY: 37,
         EBADF: 9,
         EBADMSG: 94,
         EBUSY: 16,
         ECANCELED: 89,
         ECHILD: 10,
         ECONNABORTED: 53,
         ECONNREFUSED: 61,
         ECONNRESET: 54,
         EDEADLK: 11,
         EDESTADDRREQ: 39,
         EDOM: 33,
         EDQUOT: 69,
         EEXIST: 17,
         EFAULT: 14,
         EFBIG: 27,
         EHOSTUNREACH: 65,
         EIDRM: 90,
         EILSEQ: 92,
         EINPROGRESS: 36,
         EINTR: 4,
         EINVAL: 22,
         EIO: 5,
         EISCONN: 56,
         EISDIR: 21,
         ELOOP: 62,
         EMFILE: 24,
         EMLINK: 31,
         EMSGSIZE: 40,
         EMULTIHOP: 95,
         ENAMETOOLONG: 63,
         ENETDOWN: 50,
         ENETRESET: 52,
         ENETUNREACH: 51,
         ENFILE: 23,
         ENOBUFS: 55,
         ENODATA: 96,
         ENODEV: 19,
         ENOENT: 2,
         ENOEXEC: 8,
         ENOLCK: 77,
         ENOLINK: 97,
         ENOMEM: 12,
         ENOMSG: 91,
         ENOPROTOOPT: 42,
         ENOSPC: 28,
         ENOSR: 98,
         ENOSTR: 99,
         ENOSYS: 78,
         ENOTCONN: 57,
         ENOTDIR: 20,
         ENOTEMPTY: 66,
         ENOTSOCK: 38,
         ENOTSUP: 45,
         ENOTTY: 25,
         ENXIO: 6,
         EOPNOTSUPP: 102,
         EOVERFLOW: 84,
         EPERM: 1,
         EPIPE: 32,
         EPROTO: 100,
         EPROTONOSUPPORT: 43,
         EPROTOTYPE: 41,
         ERANGE: 34,
         EROFS: 30,
         ESPIPE: 29,
         ESRCH: 3,
         ESTALE: 70,
         ETIME: 101,
         ETIMEDOUT: 60,
         ETXTBSY: 26,
         EWOULDBLOCK: 35,
         EXDEV: 18,
         SIGHUP: 1,
         SIGINT: 2,
         SIGQUIT: 3,
         SIGILL: 4,
         SIGTRAP: 5,
         SIGABRT: 6,
         SIGIOT: 6,
         SIGBUS: 10,
         SIGFPE: 8,
         SIGKILL: 9,
         SIGUSR1: 30,
         SIGSEGV: 11,
         SIGUSR2: 31,
         SIGPIPE: 13,
         SIGALRM: 14,
         SIGTERM: 15,
         SIGCHLD: 20,
         SIGCONT: 19,
         SIGSTOP: 17,
         SIGTSTP: 18,
         SIGTTIN: 21,
         SIGTTOU: 22,
         SIGURG: 16,
         SIGXCPU: 24,
         SIGXFSZ: 25,
         SIGVTALRM: 26,
         SIGPROF: 27,
         SIGWINCH: 28,
         SIGIO: 23,
         SIGSYS: 12,
         SSL_OP_ALL: 2147486719,
         SSL_OP_ALLOW_UNSAFE_LEGACY_RENEGOTIATION: 262144,
         SSL_OP_CIPHER_SERVER_PREFERENCE: 4194304,
         SSL_OP_CISCO_ANYCONNECT: 32768,
         SSL_OP_COOKIE_EXCHANGE: 8192,
         SSL_OP_CRYPTOPRO_TLSEXT_BUG: 2147483648,
         SSL_OP_DONT_INSERT_EMPTY_FRAGMENTS: 2048,
         SSL_OP_EPHEMERAL_RSA: 0,
         SSL_OP_LEGACY_SERVER_CONNECT: 4,
         SSL_OP_MICROSOFT_BIG_SSLV3_BUFFER: 32,
         SSL_OP_MICROSOFT_SESS_ID_BUG: 1,
         SSL_OP_MSIE_SSLV2_RSA_PADDING: 0,
         SSL_OP_NETSCAPE_CA_DN_BUG: 536870912,
         SSL_OP_NETSCAPE_CHALLENGE_BUG: 2,
         SSL_OP_NETSCAPE_DEMO_CIPHER_CHANGE_BUG: 1073741824,
         SSL_OP_NETSCAPE_REUSE_CIPHER_CHANGE_BUG: 8,
         SSL_OP_NO_COMPRESSION: 131072,
         SSL_OP_NO_QUERY_MTU: 4096,
         SSL_OP_NO_SESSION_RESUMPTION_ON_RENEGOTIATION: 65536,
         SSL_OP_NO_SSLv2: 16777216,
         SSL_OP_NO_SSLv3: 33554432,
         SSL_OP_NO_TICKET: 16384,
         SSL_OP_NO_TLSv1: 67108864,
         SSL_OP_NO_TLSv1_1: 268435456,
         SSL_OP_NO_TLSv1_2: 134217728,
         SSL_OP_PKCS1_CHECK_1: 0,
         SSL_OP_PKCS1_CHECK_2: 0,
         SSL_OP_SINGLE_DH_USE: 1048576,
         SSL_OP_SINGLE_ECDH_USE: 524288,
         SSL_OP_SSLEAY_080_CLIENT_DH_BUG: 128,
         SSL_OP_SSLREF2_REUSE_CERT_TYPE_BUG: 0,
         SSL_OP_TLS_BLOCK_PADDING_BUG: 512,
         SSL_OP_TLS_D5_BUG: 256,
         SSL_OP_TLS_ROLLBACK_BUG: 8388608,
         ENGINE_METHOD_DSA: 2,
         ENGINE_METHOD_DH: 4,
         ENGINE_METHOD_RAND: 8,
         ENGINE_METHOD_ECDH: 16,
         ENGINE_METHOD_ECDSA: 32,
         ENGINE_METHOD_CIPHERS: 64,
         ENGINE_METHOD_DIGESTS: 128,
         ENGINE_METHOD_STORE: 256,
         ENGINE_METHOD_PKEY_METHS: 512,
         ENGINE_METHOD_PKEY_ASN1_METHS: 1024,
         ENGINE_METHOD_ALL: 65535,
         ENGINE_METHOD_NONE: 0,
         DH_CHECK_P_NOT_SAFE_PRIME: 2,
         DH_CHECK_P_NOT_PRIME: 1,
         DH_UNABLE_TO_CHECK_GENERATOR: 4,
         DH_NOT_SUITABLE_GENERATOR: 8,
         NPN_ENABLED: 1,
         RSA_PKCS1_PADDING: 1,
         RSA_SSLV23_PADDING: 2,
         RSA_NO_PADDING: 3,
         RSA_PKCS1_OAEP_PADDING: 4,
         RSA_X931_PADDING: 5,
         RSA_PKCS1_PSS_PADDING: 6,
         POINT_CONVERSION_COMPRESSED: 2,
         POINT_CONVERSION_UNCOMPRESSED: 4,
         POINT_CONVERSION_HYBRID: 6,
         O_RDONLY: 0,
         O_WRONLY: 1,
         O_RDWR: 2,
         S_IFMT: 61440,
         S_IFREG: 32768,
         S_IFDIR: 16384,
         S_IFCHR: 8192,
         S_IFBLK: 24576,
         S_IFIFO: 4096,
         S_IFLNK: 40960,
         S_IFSOCK: 49152,
         O_CREAT: 512,
         O_EXCL: 2048,
         O_NOCTTY: 131072,
         O_TRUNC: 1024,
         O_APPEND: 8,
         O_DIRECTORY: 1048576,
         O_NOFOLLOW: 256,
         O_SYNC: 128,
         O_SYMLINK: 2097152,
         O_NONBLOCK: 4,
         S_IRWXU: 448,
         S_IRUSR: 256,
         S_IWUSR: 128,
         S_IXUSR: 64,
         S_IRWXG: 56,
         S_IRGRP: 32,
         S_IWGRP: 16,
         S_IXGRP: 8,
         S_IRWXO: 7,
         S_IROTH: 4,
         S_IWOTH: 2,
         S_IXOTH: 1,
         F_OK: 0,
         R_OK: 4,
         W_OK: 2,
         X_OK: 1,
         UV_UDP_REUSEADDR: 4,
         defaultCoreCipherList: 'ECDHE-RSA-AES128-GCM-SHA256:ECDHE-ECDSA-AES128-GCM-SHA256:ECDHE-RSA-AES256-GCM-SHA384:ECDHE-ECDSA-AES256-GCM-SHA384:DHE-RSA-AES128-GCM-SHA256:ECDHE-RSA-AES128-SHA256:DHE-RSA-AES128-SHA256:ECDHE-RSA-AES256-SHA384:DHE-RSA-AES256-SHA384:ECDHE-RSA-AES256-SHA256:DHE-RSA-AES256-SHA256:HIGH:!aNULL:!eNULL:!EXPORT:!DES:!RC4:!MD5:!PSK:!SRP:!CAMELLIA',
         defaultCipherList: 'ECDHE-RSA-AES128-GCM-SHA256:ECDHE-ECDSA-AES128-GCM-SHA256:ECDHE-RSA-AES256-GCM-SHA384:ECDHE-ECDSA-AES256-GCM-SHA384:DHE-RSA-AES128-GCM-SHA256:ECDHE-RSA-AES128-SHA256:DHE-RSA-AES128-SHA256:ECDHE-RSA-AES256-SHA384:DHE-RSA-AES256-SHA384:ECDHE-RSA-AES256-SHA256:DHE-RSA-AES256-SHA256:HIGH:!aNULL:!eNULL:!EXPORT:!DES:!RC4:!MD5:!PSK:!SRP:!CAMELLIA' } }


instead of the module I defined. The rest of the imports seem to be working fine and if I import with relative paths it works.

My app structure looks like this:

.
├── app
│   ├── components
│   ├── constants
│   └── some other code
└── package.json and other config stuff

and my config is

"jest": {
    "testRegex": "Spec\\.js$",
    "modulePaths": ["app/components", "app", "node_modules" ],
    "rootDir": "app"
  },
picture natenorberg

Most helpful comment

Actually, you can mock the constants node module by yours:
jest.mock('constants', () => require('path/to/your/constants'))
It solved my problem.

picture anta-semenov on 16 Dec 2016
👍7

All 13 comments

Can you provide a repo with this bug? Thank you.

cpojer picture cpojer on 7 Sep 2016

Sure, this repo shows the issue when you import 'constants'. I didn't get the modulePaths config working (it was my first time using create-react-app) but the import shows the strange constants object that I was seeing in the other repo.

Sorry it's not the same repo. I was playing around with it in a large repo for work that I can't make open source.

natenorberg picture natenorberg on 7 Sep 2016

If you use create-react-app you cannot customize your Jest configuration.

cpojer picture cpojer on 7 Sep 2016

Yeah, that's what I realized. But do you have any idea of how it's resolving the constants module?
Even without customizing the jest configuration it does something different if a module is named 'constants'

natenorberg picture natenorberg on 7 Sep 2016

Constants is a node core module. If you type node and then require('constants') in the repl, it'll give you that module.

cpojer picture cpojer on 7 Sep 2016
👍1

Oh ok. So is there a way to try to match in the modulePaths from your jest config first? Or do you just have to name your constants file something different if you want to use jest?

natenorberg picture natenorberg on 7 Sep 2016

Yeah, in Jest the resolution algorithm always looks at core modules first and returns them, you'll probably need to rename it. I'm sorry, we can't really fix this :(

cpojer picture cpojer on 7 Sep 2016
👍1

Ok, bummer, thanks for your help though.

natenorberg picture natenorberg on 7 Sep 2016

We could do this, however we are following node's module resolution algorithm which always prefers core modules over other modules that may match, see https://nodejs.org/api/modules.html#modules_core_modules

cpojer picture cpojer on 7 Sep 2016
👍1

Actually, you can mock the constants node module by yours:
jest.mock('constants', () => require('path/to/your/constants'))
It solved my problem.

anta-semenov picture anta-semenov on 16 Dec 2016
👍7

Oh thanks. I just renamed my constants file to appConstants.js

natenorberg picture natenorberg on 16 Dec 2016
👍1

@cpojer Thanks for your info here, I just spent a frustrating few hours messing about with modulePaths, moduleNameMapper and moduleDirectories. Changing from constants/index.js to appconstants/index.js got things running for me.

dougajmcdonald picture dougajmcdonald on 20 Jun 2018

I found that using import { exampleConstants } from 'constants/index' works in our use case where constants is a folder containing an index file with all our constants. I'm using typescript and create-react-app and a tsconfig.json that has paths set to: 

"paths": {
            "constants/*": ["src/constants/*"],
            "constants": ["src/constants"],
}

In our package.json we have a jest config like so:

...
"jest": {
    "moduleNameMapper": {
        "^constants$": "<rootDir>/src/constants",
        "^constants/(.*)$": "<rootDir>/src/constants/$1",
    }
},
...

This is not as nice as just having constants but it's the closest we could come given the node module conflict.

inlightmedia picture inlightmedia on 22 Feb 2019
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