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util: Change how Error objects are formatted #4582

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@zeusdeux zeusdeux commented Jan 8, 2016

Previously, Error objects were formatted as the result of a toString
call bounded by square brackets. They are now formatted as the stack
trace for the given error object. The intention initially was to emulate
how browsers do console.error but since that would also impact
console.warn, console.log, etc, it was decided to make the change at
util.inspect level which is in turn used by the console package.

This is definitely a semver-major change.

Bigger discussion @ #4452

@@ -55,13 +55,16 @@ assert.equal(util.format('%%%s%%%%', 'hi'), '%hi%%');
})();

// Errors
assert.equal(util.format(new Error('foo')), '[Error: foo]');
const err = new Error('foo');

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@jasnell

jasnell Jan 8, 2016
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While you're working in this file, can you change the require() statements at the top to use const as well?

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@zeusdeux

zeusdeux Jan 8, 2016
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Doing this in both test-util-format.js and test-util-inspect.js.

@jasnell
jasnell reviewed Jan 8, 2016
View changes
test/parallel/test-util-inspect.js Outdated
assert.equal(util.inspect(new Error('FAIL')), '[Error: FAIL]');
assert.equal(util.inspect(new TypeError('FAIL')), '[TypeError: FAIL]');
assert.equal(util.inspect(new SyntaxError('FAIL')), '[SyntaxError: FAIL]');
var errors = [];

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@jasnell

jasnell Jan 8, 2016
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can be const also

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@zeusdeux

zeusdeux Jan 8, 2016
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const when pushing into the array makes me uncomfortable. Makes const a lie. :(

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@jasnell

jasnell Jan 8, 2016
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that's fine.. more stylistic than anything else :-)

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@zeusdeux

zeusdeux Jan 8, 2016
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So I'll leave it be then! :)

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@mscdex

mscdex Jan 8, 2016
Contributor

I thought const was to designate a variable that is only assigned once, not a value that is never mutated (e.g. a property added or an element added to an array)?

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@jasnell

jasnell Jan 8, 2016
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@mscdex ... you're correct. const variables can be mutated. in this instance, tho, within the test, whether it's a var or const doesn't make much difference. More a style choice.

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@cjihrig

cjihrig Jan 8, 2016
Contributor

I'd still lean toward const, as it could help catch a potential bug... our tests are far from perfect :-)

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@bnoordhuis

bnoordhuis Jan 8, 2016
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Another vote for const. A value is not its referent; knowing that a referent cannot be reassigned makes it easier to keep the program state in your head. The current rule of thumb in core is (or should be): const if you can, let or var if you must.

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@jasnell jasnell commented Jan 8, 2016

LGTM
But I'd like to get other @nodejs/ctc opinions also

@zeusdeux zeusdeux force-pushed the zeusdeux:issue-4452 branch Jan 8, 2016
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@bnoordhuis bnoordhuis commented Jan 8, 2016

LGTM-ish in that I think it's a useful change. Less LGTM in that it probably doesn't format well when you util.inspect() an object graph with an Error object a few levels deep.

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@zeusdeux zeusdeux commented Jan 8, 2016

@bnoordhuis It does format kinda weird when there is an error object as a part of another object/array but the behaviour is now similar to that in browsers. It looks something like below:

{ a: 10,
  b:
   { c: 'nope',
     d:
      Error
          at repl:1:40
          at REPLServer.defaultEval (repl.js:252:27)
          at bound (domain.js:287:14)
          at REPLServer.runBound [as eval] (domain.js:300:12)
          at REPLServer.<anonymous> (repl.js:417:12)
          at emitOne (events.js:83:20)
          at REPLServer.emit (events.js:170:7)
          at REPLServer.Interface._onLine (readline.js:215:10)
          at REPLServer.Interface._line (readline.js:554:8)
          at REPLServer.Interface._ttyWrite (readline.js:831:14) } }
@zeusdeux zeusdeux force-pushed the zeusdeux:issue-4452 branch Jan 8, 2016
Previously, Error objects were formatted as the result of a `toString`
call bounded by square brackets. They are now formatted as the stack
trace for the given error object. The intention initially was to emulate
how browsers do `console.error` but since that would also impact
`console.warn`, `console.log`, etc, it was decided to make the change at
`util.inspect` level which is in turn used by the `console` package.

Fixes: #4452
@zeusdeux zeusdeux force-pushed the zeusdeux:issue-4452 branch to 006a66a Jan 8, 2016
@@ -488,7 +488,7 @@ function formatPrimitiveNoColor(ctx, value) {


function formatError(value) {
return '[' + Error.prototype.toString.call(value) + ']';
return value.stack || '[' + Error.prototype.toString.call(value) + ']';

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@zeusdeux

zeusdeux Jan 8, 2016
Author Member

Added fallback in case the error is some custom error that isn't capturing the stack correctly.

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@bnoordhuis

bnoordhuis Jan 9, 2016
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Can you add a regression test for that? EDIT: Nevermind, I see BadCustomError covers that.

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@bnoordhuis bnoordhuis commented Jan 9, 2016

LGTM. One more sign-off would be good.

@trevnorris
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@trevnorris trevnorris commented Jan 9, 2016

LGTM

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@cjihrig
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@cjihrig cjihrig commented Jan 9, 2016

LGTM

jasnell added a commit that referenced this pull request Jan 11, 2016
Previously, Error objects were formatted as the result of a `toString`
call bounded by square brackets. They are now formatted as the stack
trace for the given error object. The intention initially was to emulate
how browsers do `console.error` but since that would also impact
`console.warn`, `console.log`, etc, it was decided to make the change at
`util.inspect` level which is in turn used by the `console` package.

Fixes: #4452
PR-URL: #4582
Reviewed-By: Ben Noordhuis <info@bnoordhuis.nl>
Reviewed-By: Trevor Norris <trev.norris@gmail.com>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: James M Snell <jasnell@gmail.com>
@jasnell
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@jasnell jasnell commented Jan 11, 2016

Landed in e2f47f5

@jasnell jasnell closed this Jan 11, 2016
@jasnell jasnell mentioned this pull request Mar 17, 2016
scovetta pushed a commit to scovetta/node that referenced this pull request Apr 2, 2016
Previously, Error objects were formatted as the result of a `toString`
call bounded by square brackets. They are now formatted as the stack
trace for the given error object. The intention initially was to emulate
how browsers do `console.error` but since that would also impact
`console.warn`, `console.log`, etc, it was decided to make the change at
`util.inspect` level which is in turn used by the `console` package.

Fixes: nodejs#4452
PR-URL: nodejs#4582
Reviewed-By: Ben Noordhuis <info@bnoordhuis.nl>
Reviewed-By: Trevor Norris <trev.norris@gmail.com>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: James M Snell <jasnell@gmail.com>
@jasnell jasnell mentioned this pull request Apr 19, 2016
jasnell added a commit that referenced this pull request Apr 26, 2016
The following significant (semver-major) changes have been made since the
previous Node v5.0.0 release.

* Buffer
  * New Buffer constructors have been added
    [#4682](#4682)
  * Previously deprecated Buffer APIs are removed
    [#5048](#5048),
    [#4594](#4594)
  * Improved error handling [#4514](#4514)
* Cluster
  * Worker emitted as first argument in 'message' event
    [#5361](#5361).
* Crypto
  * Improved error handling [#3100](#3100),
    [#5611](#5611)
  * Simplified Certificate class bindings
    [#5382](#5382)
  * Improved control over FIPS mode
    [#5181](#5181)
  * pbkdf2 digest overloading is deprecated
    [#4047](#4047)
* Dependencies
  * Reintroduce shared c-ares build support
    [#5775](#5775).
  * V8 updated to 5.0.71.31 [#6111](#6111).
* DNS
  * Add resolvePtr API to query plain DNS PTR records
    [#4921](#4921).
* Domains
  * Clear stack when no error handler
  [#4659](#4659).
* File System
  * The `fs.realpath()` and `fs.realpathSync()` methods have been updated
    to use a more efficient libuv implementation. This change includes the
    removal of the `cache` argument and the method can throw new errors
    [#3594](#3594)
  * FS apis can now accept and return paths as Buffers
    [#5616](#5616).
  * Error handling and type checking improvements
    [#5616](#5616),
    [#5590](#5590),
    [#4518](#4518),
    [#3917](#3917).
  * fs.read's string interface is deprecated
    [#4525](#4525)
* HTTP
  * 'clientError' can now be used to return custom errors from an
    HTTP server [#4557](#4557).
* Modules
  * Current directory is now prioritized for local lookups
    [#5689](#5689)
  * Symbolic links are preserved when requiring modules
    [#5950](#5950)
* Net
  * DNS hints no longer implicitly set
    [#6021](#6021).
  * Improved error handling and type checking
    [#5981](#5981),
    [#5733](#5733),
    [#2904](#2904)
* Path
  * Improved type checking [#5348](#5348).
* Process
  * Introduce process warnings API
    [#4782](#4782).
  * Throw exception when non-function passed to nextTick
    [#3860](#3860).
* Readline
  * Emit key info unconditionally
    [#6024](#6024)
* REPL
  * Assignment to `_` will emit a warning.
    [#5535](#5535)
* Timers
  * Fail early when callback is not a function
    [#4362](#4362)
* TLS
  * Rename 'clientError' to 'tlsClientError'
    [#4557](#4557)
  * SHA1 used for sessionIdContext
    [#3866](#3866)
* TTY
  * Previously deprecated setRawMode wrapper is removed
    [#2528](#2528).
* Util
  * Changes to Error object formatting
    [#4582](#4582).
* Windows
  * Windows XP and Vista are no longer supported
    [#5167](#5167),
    [#5167](#5167).
jasnell added a commit that referenced this pull request Apr 26, 2016
The following significant (semver-major) changes have been made since the
previous Node v5.0.0 release.

* Buffer
  * New Buffer constructors have been added
    [#4682](#4682)
  * Previously deprecated Buffer APIs are removed
    [#5048](#5048),
    [#4594](#4594)
  * Improved error handling [#4514](#4514)
* Cluster
  * Worker emitted as first argument in 'message' event
    [#5361](#5361).
* Crypto
  * Improved error handling [#3100](#3100),
    [#5611](#5611)
  * Simplified Certificate class bindings
    [#5382](#5382)
  * Improved control over FIPS mode
    [#5181](#5181)
  * pbkdf2 digest overloading is deprecated
    [#4047](#4047)
* Dependencies
  * Reintroduce shared c-ares build support
    [#5775](#5775).
  * V8 updated to 5.0.71.31 [#6111](#6111).
* DNS
  * Add resolvePtr API to query plain DNS PTR records
    [#4921](#4921).
* Domains
  * Clear stack when no error handler
  [#4659](#4659).
* File System
  * The `fs.realpath()` and `fs.realpathSync()` methods have been updated
    to use a more efficient libuv implementation. This change includes the
    removal of the `cache` argument and the method can throw new errors
    [#3594](#3594)
  * FS apis can now accept and return paths as Buffers
    [#5616](#5616).
  * Error handling and type checking improvements
    [#5616](#5616),
    [#5590](#5590),
    [#4518](#4518),
    [#3917](#3917).
  * fs.read's string interface is deprecated
    [#4525](#4525)
* HTTP
  * 'clientError' can now be used to return custom errors from an
    HTTP server [#4557](#4557).
* Modules
  * Current directory is now prioritized for local lookups
    [#5689](#5689)
  * Symbolic links are preserved when requiring modules
    [#5950](#5950)
* Net
  * DNS hints no longer implicitly set
    [#6021](#6021).
  * Improved error handling and type checking
    [#5981](#5981),
    [#5733](#5733),
    [#2904](#2904)
* Path
  * Improved type checking [#5348](#5348).
* Process
  * Introduce process warnings API
    [#4782](#4782).
  * Throw exception when non-function passed to nextTick
    [#3860](#3860).
* Readline
  * Emit key info unconditionally
    [#6024](#6024)
* REPL
  * Assignment to `_` will emit a warning.
    [#5535](#5535)
* Timers
  * Fail early when callback is not a function
    [#4362](#4362)
* TLS
  * Rename 'clientError' to 'tlsClientError'
    [#4557](#4557)
  * SHA1 used for sessionIdContext
    [#3866](#3866)
* TTY
  * Previously deprecated setRawMode wrapper is removed
    [#2528](#2528).
* Util
  * Changes to Error object formatting
    [#4582](#4582).
* Windows
  * Windows XP and Vista are no longer supported
    [#5167](#5167),
    [#5167](#5167).
jasnell added a commit that referenced this pull request Apr 26, 2016
The following significant (semver-major) changes have been made since the
previous Node v5.0.0 release.

* Buffer
  * New Buffer constructors have been added
    [#4682](#4682)
  * Previously deprecated Buffer APIs are removed
    [#5048](#5048),
    [#4594](#4594)
  * Improved error handling [#4514](#4514)
* Cluster
  * Worker emitted as first argument in 'message' event
    [#5361](#5361).
* Crypto
  * Improved error handling [#3100](#3100),
    [#5611](#5611)
  * Simplified Certificate class bindings
    [#5382](#5382)
  * Improved control over FIPS mode
    [#5181](#5181)
  * pbkdf2 digest overloading is deprecated
    [#4047](#4047)
* Dependencies
  * Reintroduce shared c-ares build support
    [#5775](#5775).
  * V8 updated to 5.0.71.31 [#6111](#6111).
* DNS
  * Add resolvePtr API to query plain DNS PTR records
    [#4921](#4921).
* Domains
  * Clear stack when no error handler
  [#4659](#4659).
* File System
  * The `fs.realpath()` and `fs.realpathSync()` methods have been updated
    to use a more efficient libuv implementation. This change includes the
    removal of the `cache` argument and the method can throw new errors
    [#3594](#3594)
  * FS apis can now accept and return paths as Buffers
    [#5616](#5616).
  * Error handling and type checking improvements
    [#5616](#5616),
    [#5590](#5590),
    [#4518](#4518),
    [#3917](#3917).
  * fs.read's string interface is deprecated
    [#4525](#4525)
* HTTP
  * 'clientError' can now be used to return custom errors from an
    HTTP server [#4557](#4557).
* Modules
  * Current directory is now prioritized for local lookups
    [#5689](#5689)
  * Symbolic links are preserved when requiring modules
    [#5950](#5950)
* Net
  * DNS hints no longer implicitly set
    [#6021](#6021).
  * Improved error handling and type checking
    [#5981](#5981),
    [#5733](#5733),
    [#2904](#2904)
* OS X
  * MACOSX_DEPLOYMENT_TARGET has been bumped up to 10.7
    [#6402](#6402).
* Path
  * Improved type checking [#5348](#5348).
* Process
  * Introduce process warnings API
    [#4782](#4782).
  * Throw exception when non-function passed to nextTick
    [#3860](#3860).
* Readline
  * Emit key info unconditionally
    [#6024](#6024)
* REPL
  * Assignment to `_` will emit a warning.
    [#5535](#5535)
* Timers
  * Fail early when callback is not a function
    [#4362](#4362)
* TLS
  * Rename 'clientError' to 'tlsClientError'
    [#4557](#4557)
  * SHA1 used for sessionIdContext
    [#3866](#3866)
* TTY
  * Previously deprecated setRawMode wrapper is removed
    [#2528](#2528).
* Util
  * Changes to Error object formatting
    [#4582](#4582).
* Windows
  * Windows XP and Vista are no longer supported
    [#5167](#5167),
    [#5167](#5167).
jasnell added a commit that referenced this pull request Apr 26, 2016
The following significant (semver-major) changes have been made since the
previous Node v5.0.0 release.

* Buffer
  * New Buffer constructors have been added
    [#4682](#4682)
  * Previously deprecated Buffer APIs are removed
    [#5048](#5048),
    [#4594](#4594)
  * Improved error handling [#4514](#4514)
* Cluster
  * Worker emitted as first argument in 'message' event
    [#5361](#5361).
* Crypto
  * Improved error handling [#3100](#3100),
    [#5611](#5611)
  * Simplified Certificate class bindings
    [#5382](#5382)
  * Improved control over FIPS mode
    [#5181](#5181)
  * pbkdf2 digest overloading is deprecated
    [#4047](#4047)
* Dependencies
  * Reintroduce shared c-ares build support
    [#5775](#5775).
  * V8 updated to 5.0.71.31 [#6111](#6111).
* DNS
  * Add resolvePtr API to query plain DNS PTR records
    [#4921](#4921).
* Domains
  * Clear stack when no error handler
  [#4659](#4659).
* File System
  * The `fs.realpath()` and `fs.realpathSync()` methods have been updated
    to use a more efficient libuv implementation. This change includes the
    removal of the `cache` argument and the method can throw new errors
    [#3594](#3594)
  * FS apis can now accept and return paths as Buffers
    [#5616](#5616).
  * Error handling and type checking improvements
    [#5616](#5616),
    [#5590](#5590),
    [#4518](#4518),
    [#3917](#3917).
  * fs.read's string interface is deprecated
    [#4525](#4525)
* HTTP
  * 'clientError' can now be used to return custom errors from an
    HTTP server [#4557](#4557).
* Modules
  * Current directory is now prioritized for local lookups
    [#5689](#5689)
  * Symbolic links are preserved when requiring modules
    [#5950](#5950)
* Net
  * DNS hints no longer implicitly set
    [#6021](#6021).
  * Improved error handling and type checking
    [#5981](#5981),
    [#5733](#5733),
    [#2904](#2904)
* OS X
  * MACOSX_DEPLOYMENT_TARGET has been bumped up to 10.7
    [#6402](#6402).
* Path
  * Improved type checking [#5348](#5348).
* Process
  * Introduce process warnings API
    [#4782](#4782).
  * Throw exception when non-function passed to nextTick
    [#3860](#3860).
* Readline
  * Emit key info unconditionally
    [#6024](#6024)
* REPL
  * Assignment to `_` will emit a warning.
    [#5535](#5535)
* Timers
  * Fail early when callback is not a function
    [#4362](#4362)
* TLS
  * Rename 'clientError' to 'tlsClientError'
    [#4557](#4557)
  * SHA1 used for sessionIdContext
    [#3866](#3866)
* TTY
  * Previously deprecated setRawMode wrapper is removed
    [#2528](#2528).
* Util
  * Changes to Error object formatting
    [#4582](#4582).
* Windows
  * Windows XP and Vista are no longer supported
    [#5167](#5167),
    [#5167](#5167).
jasnell added a commit that referenced this pull request Apr 26, 2016
The following significant (semver-major) changes have been made since the
previous Node v5.0.0 release.

* Buffer
  * New Buffer constructors have been added
    [#4682](#4682)
  * Previously deprecated Buffer APIs are removed
    [#5048](#5048),
    [#4594](#4594)
  * Improved error handling [#4514](#4514)
* Cluster
  * Worker emitted as first argument in 'message' event
    [#5361](#5361).
* Crypto
  * Improved error handling [#3100](#3100),
    [#5611](#5611)
  * Simplified Certificate class bindings
    [#5382](#5382)
  * Improved control over FIPS mode
    [#5181](#5181)
  * pbkdf2 digest overloading is deprecated
    [#4047](#4047)
* Dependencies
  * Reintroduce shared c-ares build support
    [#5775](#5775).
  * V8 updated to 5.0.71.31 [#6111](#6111).
* DNS
  * Add resolvePtr API to query plain DNS PTR records
    [#4921](#4921).
* Domains
  * Clear stack when no error handler
  [#4659](#4659).
* File System
  * The `fs.realpath()` and `fs.realpathSync()` methods have been updated
    to use a more efficient libuv implementation. This change includes the
    removal of the `cache` argument and the method can throw new errors
    [#3594](#3594)
  * FS apis can now accept and return paths as Buffers
    [#5616](#5616).
  * Error handling and type checking improvements
    [#5616](#5616),
    [#5590](#5590),
    [#4518](#4518),
    [#3917](#3917).
  * fs.read's string interface is deprecated
    [#4525](#4525)
* HTTP
  * 'clientError' can now be used to return custom errors from an
    HTTP server [#4557](#4557).
* Modules
  * Current directory is now prioritized for local lookups
    [#5689](#5689)
  * Symbolic links are preserved when requiring modules
    [#5950](#5950)
* Net
  * DNS hints no longer implicitly set
    [#6021](#6021).
  * Improved error handling and type checking
    [#5981](#5981),
    [#5733](#5733),
    [#2904](#2904)
* OS X
  * MACOSX_DEPLOYMENT_TARGET has been bumped up to 10.7
    [#6402](#6402).
* Path
  * Improved type checking [#5348](#5348).
* Process
  * Introduce process warnings API
    [#4782](#4782).
  * Throw exception when non-function passed to nextTick
    [#3860](#3860).
* Readline
  * Emit key info unconditionally
    [#6024](#6024)
* REPL
  * Assignment to `_` will emit a warning.
    [#5535](#5535)
* Timers
  * Fail early when callback is not a function
    [#4362](#4362)
* TLS
  * Rename 'clientError' to 'tlsClientError'
    [#4557](#4557)
  * SHA1 used for sessionIdContext
    [#3866](#3866)
* TTY
  * Previously deprecated setRawMode wrapper is removed
    [#2528](#2528).
* Util
  * Changes to Error object formatting
    [#4582](#4582).
* Windows
  * Windows XP and Vista are no longer supported
    [#5167](#5167),
    [#5167](#5167).
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