Check whether Babel returned a source map

[isnifer]

Prerequisites

installed Source Map Support

Description

With installed Source Map Support tests in async function won't show errors correctly
Screenshot WITH installed source maps support
Screenshot WITHOUT installed source maps support

Test Source

t.falsy(1, 'List of nearby stores should not be empty')

Error Message & Stack Trace

  ✔ 02_NearbyStoreList › Nearby Store List (1.5s)
Uncaught Exception: __tests__/scenarios/07_StoreTabView.test.js
  TypeError: Cannot read property 'sections' of null
  new SourceMapConsumer (node_modules/ava/node_modules/source-map/lib/source-map-consumer.js:20:20)
mapSourcePosition (node_modules/ava/node_modules/source-map-support/source-map-support.js:191:14)
wrapCallSite (node_modules/ava/node_modules/source-map-support/source-map-support.js:359:20)
node_modules/ava/node_modules/source-map-support/source-map-support.js:394:26
Function.prepareStackTrace (node_modules/ava/node_modules/source-map-support/source-map-support.js:393:24)


  ✖ Test results were not received from __tests__/scenarios/07_StoreTabView.test.js

  1 test passed [16:49:31]
  2 uncaught exceptions

Config

Copy the relevant section from package.json:

{
  "files": [
    "__tests__/scenarios/*.test.js"
  ],
  "sources": [
    "web/index.js"
  ],
  "require": [
    "./__tests__/setup/tape.js"
  ],
  "failFast": true,
  "failWithoutAssertions": true,
  "compileEnhancements": false,
  "babel": "inherit"
}

Command-Line Arguments

Copy your npm build scripts or the ava command used:

ava --vebose --watch

Environment

Tell us which operating system you are using, as well as which versions of Node.js, npm, and AVA. Run the following to get it quickly:

Node.js v9.4.0
darwin 17.5.0
ava --version 0.25.0
npm --version 6.0.1

[isnifer]

I will try to create reproducible demo

[isnifer]

Did some debug and found — this line

ava/lib/worker/precompiler-hook.js

Line 19 in 1e0e8e8

map: fs.readFileSync(sourceMapCache.get(source), 'utf8')

returns null as a string.
It brokes log.

If I change locally to:

if (sourceMapCache.has(source)) {
  const map = fs.readFileSync(sourceMapCache.get(source), 'utf8')

  if (map !== 'null') {
    return {
      url: source,
      map: map
    };
  }
}

Then there is no problem

[novemberborn]

Wow that's surprising, nice find @isnifer!

Can you share this reproduction? And does it occur when you install ava@next?

[isnifer]

@novemberborn yes, I will. Just need some free time.
Also, I will check it with ava@next. Thank you for your response.

[novemberborn]

Looking through the source code we're assuming that Babel returns us a source map, and that's probably a wrong assumption:

ava/lib/caching-precompiler.js

Line 71 in 2167c57

fs.writeFileSync(mapPath, JSON.stringify(result.map));

This leads to the 'null' string.

We'll have to update the worker/precompiler-hook module accordingly. We don't need the sourceMapCache value at all, we can compute the source map location from the options. We just need to catch any errors if the file does not exist.

Do you happen to have source maps disabled in your Babel options?

[novemberborn]

Note that we may remove our source-map-support integration entirely: #974 (comment)

We should still fix this bug while #974 is pending.

[novemberborn]

Fixing this should wait until #1798 lands.

[isnifer]

@novemberborn

Do you happen to have source maps disabled in your Babel options?

No