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seanmonstar / insist

A drop-in replacement for `assert` with a better default message.
Mozilla Public License 2.0
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In REPL, TypeError: Cannot read property 'toString' of undefined #2

Open ivan opened 9 years ago

ivan commented 9 years ago

Testing insist with io.js 2.1.0 in the REPL:

# iojs
> let assert = require('insist');
undefined
> assert.equal(3, 4);
TypeError: Cannot read property 'toString' of undefined
    at getMessage (/mnt/devdrive/NodeProjects/asserttests/node_modules/insist/insist.js:84:21)
    at Function.insist (/mnt/devdrive/NodeProjects/asserttests/node_modules/insist/insist.js:96:22)
    at repl:1:8
    at REPLServer.defaultEval (repl.js:155:27)
    at bound (domain.js:254:14)
    at REPLServer.runBound [as eval] (domain.js:267:12)
    at REPLServer.<anonymous> (repl.js:309:12)
    at emitOne (events.js:82:20)
    at REPLServer.emit (events.js:169:7)
    at REPLServer.Interface._onLine (readline.js:208:10)

trace.fun is undefined at https://github.com/seanmonstar/insist/blob/2f8d497cf58d7a6c978565a0b1ab8eda8529c0cc/insist.js#L84 and I don't know why. This happens even if I move the assert into a function in the REPL.

seanmonstar commented 9 years ago

Er, should it even be trace.fun? Looking at stack-trace, it seems trace.getFunction() would be the right way? If that works, would you mind filing a PR?

fatso83 commented 9 years ago

That does not work. I was about to file a PR, when I tested this in the console. Using let is doing something to the CallSite object, not sure what, but it does not matter if substituting fun for getFunction(). I tried ... Substituting let for var in the example will run just fine, btw.

This bug only manifests itself in the REPL btw, so to test it one can do this:

$ iojs --use-strict -i << EOF
> let assert = require('./insist');
> assert.equal(3, 4);
> let assert = require('./insist');
undefined
> assert.equal(3, 4);
TypeError: Cannot read property 'toString' of undefined
    at getMessage (/Users/carl-erik.kopseng/dev-priv/insist/insist.js:84:31)
    at Function.insist [as equal] (/Users/carl-erik.kopseng/dev-priv/insist/insist.js:99:22)
    at repl:1:8
    at REPLServer.defaultEval (repl.js:164:27)
    at bound (domain.js:250:14)
    at REPLServer.runBound [as eval] (domain.js:263:12)
    at REPLServer.<anonymous> (repl.js:392:12)
    at emitOne (events.js:82:20)
    at REPLServer.emit (events.js:169:7)
    at REPLServer.Interface._onLine (readline.js:210:10)
>

I see that better-assert does this fine, so maybe a fix could be to use tj/callsite like it does? Might change the look of the stacktraces, though.