Include anonymous functions (whose name node cannot infer) in stack traces #1313
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@neoeno could you share an example of how this changes AVA's output, and what is missing in the current output? The stack trace you shared comes from Node.js itself but I can't quite see how it impacts AVA's output. |
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Of course @novemberborn — sorry I didn't do this already! Here's a repo with reproduction, output both before and after this PR: https://github.com/neoeno/ava-pr-1313-example For posterity, here's the code: import test from 'ava';
const fn = () => () => doesnotexist;
test("some test", t => {
fn()();
});Here's the current output (as of 3da8603): And here's the output after this PR: |
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I'll fix that formatting error too 😨 |
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@vadimdemedes how did you arrive at the regular expression? Looks like |
lib/extract-stack.js
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| module.exports = stack => { | ||
| return stack | ||
| .split('\n') | ||
| .filter(line => stackLineRegex.test(line)) | ||
| .filter(line => namedFunctionStackLineRegex.test(line) || anonymousFunctionStackLineRegex.test(line)) |
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I think you should combine this into a singular regular expression.
Some functions are more anonymous than others. Node does a pretty
good job of naming functions like this:
```js
const fn = () => { throw "whoops!" } // <-- gets named `fn` in stacktraces
```
But in some cases a function genuinely has no name, e.g.
```js
const fn = () => () => { throw "whoops!" } // <-- inner function has no name!
```
This means we get stacktraces like this:
```
whoops!
path/to/file.js:1:1
Test.t (test.js:1:1)
```
Before this commit, the regex in `extract-stack.js` was not anticipating
stacktraces of this form, and would simply filter out the anonymous functions.
This made my life a little more awkward, as I could only see the failing test
line and the error, not the code that was actually erroring.
This commit adds another regex to `extract-stack.js` which matches on anonymous
function stacktrace lines too.
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@novemberborn I think I tried to make a regex that'd be as simple as possible and match "standard" stack lines. The point of that was to get only stack from err.stack. |
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I think the regex could still be looser. I decided to extract it into a separate module as it can be useful for other projects too: https://github.com/sindresorhus/extract-stack @neoeno Can you update to use that module and remove |
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I'll give it a go — though afaict it won't be as simple as replacing This is because at the moment No Here's where my knowledge gets a bit hazy, but it looks like it passes through So the solution would seem to be to do all this stacky work in one place and delegate to |
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My hunch is that we should extract the stack when serializing (filter out unnecessary bits early), and beautify it in the mini and verbose reporters. Though I'm not even sure what |
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Hit the same issue. I'm using an async wrapper function inside of a test, and any code inside loses it's context in the traceback. This would be super helpful to get the error context back. |
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+1 |
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@neoeno will you have a chance to get back to this? If not, perhaps @bchapman, @zabawaba99 or @patrickrand want to give it a go? 😄 |
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Though this is still on my radar I suspect I won't get to it imminently. As such, if anyone is keen to take it on I should certainly give way! |
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I don't think I'll be able to get to this immediately either but I will post if I'm able to start looking into it! |
Issue
Functions whose name node cannot infer do not get included in stack traces.
I came across this issue when working with curried functions.
Reproduction
This error in a code using an anonymous function:
Produces a stacktrace line without a function name:
The regex in extract-stack.js:2 expects the function name & brackets to be there:
So that line gets swallowed. Which means we lose context for our error message. This is a shame.
Fix
This commit fixes the issue by adding another regex to
extract-stack.jswhich will match anonymous functions.The regex may be a little broad — I couldn't think of any obvious instances where it would fail but undoubtedly some contrived examples exist.
I have included a unit test and an integration test. A few different areas in the codebase amend stacktraces, so I thought it was best to do so.
Finally
Thanks for all your great work on Ava!