Tests randomly crashing at ProviderError.ExtendableError on Ubuntu (Linux)

• I’ve asked for help in the Truffle Gitter before filing this issue.

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Issue

On a Ubuntu Linux environment (Trusty), tests randomly fail with this ExtendableError:

1) Contract: TopicEvent "after each" hook for "throws on an invalid result index":
Error: Could not connect to your Ethereum client. Please check that your Ethereum client:
    - is running
    - is accepting RPC connections (i.e., "--rpc" option is used in geth)
    - is accessible over the network
    - is properly configured in your Truffle configuration file (truffle.js)

      at ProviderError.ExtendableError (/home/travis/.nvm/versions/node/v8.9.3/lib/node_modules/truffle/build/cli.bundled.js:9401:17)
      at new ProviderError (/home/travis/.nvm/versions/node/v8.9.3/lib/node_modules/truffle/build/cli.bundled.js:325054:24)
      at /home/travis/.nvm/versions/node/v8.9.3/lib/node_modules/truffle/build/cli.bundled.js:325137:17
      at /home/travis/.nvm/versions/node/v8.9.3/lib/node_modules/truffle/build/cli.bundled.js:325195:24
      at XMLHttpRequest.request.onreadystatechange (/home/travis/.nvm/versions/node/v8.9.3/lib/node_modules/truffle/build/cli.bundled.js:328229:7)
      at XMLHttpRequestEventTarget.dispatchEvent (/home/travis/.nvm/versions/node/v8.9.3/lib/node_modules/truffle/build/cli.bundled.js:176415:18)
      at XMLHttpRequest._setReadyState (/home/travis/.nvm/versions/node/v8.9.3/lib/node_modules/truffle/build/cli.bundled.js:176705:12)
      at XMLHttpRequest._onHttpRequestError (/home/travis/.nvm/versions/node/v8.9.3/lib/node_modules/truffle/build/cli.bundled.js:176895:12)
      at ClientRequest.<anonymous> (/home/travis/.nvm/versions/node/v8.9.3/lib/node_modules/truffle/build/cli.bundled.js:176765:24)
      at Socket.socketOnEnd (_http_client.js:423:9)
      at endReadableNT (_stream_readable.js:1056:12)
      at _combinedTickCallback (internal/process/next_tick.js:138:11)

Specifically, I have a Travis-CI (continuous integration) setup and this is where the tests are failing. My local Mac OSX environment passes these tests with no problem. Every once and a while, they will fail with the same error, but I just run the tests again and they pass.

I’d say it happens like 10-15% of the time on Mac OSX, but it happens like 60-80% of the time on the Travis-CI linux env.

It feels like it used to have this error less on earlier Truffle versions. I just updated to 4.0.4 and it seems way more often now.

Steps to Reproduce

1. Clone this repo: https://github.com/bodhiproject/bodhi-core
2. Use Truffle v4.0.4 on a Ubuntu Linux environment (see environment details)
3. truffle test

Expected Behavior

Tests should pass like they do on Mac OSX env.

Actual Results

I test this on my local machine (mac osx), when all tests pass which they do, I push up to Github. Then it fires off a Travis-CI test on the linux env and fails pretty much every time.

Environment

Travis-CI Env (fails)

• Operating System: Ubuntu 14.04 Trusty
• Truffle version: 4.0.4
• node version: v8.9.3
• npm version: 5.5.1
• nvm version: 0.33.8
• Build language: node_js
• Build group: stable
• Build dist: trusty
• Distributor ID: Ubuntu
• Description: Ubuntu 14.04.5 LTS
• Release: 14.04
• Codename: trusty
• Compiled with gcc 4.8.2 for Unix (Linux ELF) on Oct 21 2013.
• OS/Arch: linux/amd64

Mac OSX Env (passes)

• Mac OSX 10.12.6 Sierra
• Truffle v4.0.4
• node version: 8.9.1
• npm version: 5.5.1

$ gcc --version:

Configured with: --prefix=/Applications/Xcode.app/Contents/Developer/usr --with-gxx-include-dir=/usr/include/c++/4.2.1
Apple LLVM version 9.0.0 (clang-900.0.39.2)
Target: x86_64-apple-darwin16.7.0
Thread model: posix
InstalledDir: /Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin

[cgewecke]

@benjamincburns Yes, it turns out this originates at web3 and they’re fixing it in beta.36.

(It was keep-alive - the change).

[barakman]

@cgewecke: I have removed all my root-level hooks, and i’m still encountering disconnections. However, in opposed to before, the errors that I am getting are always "after each" hook.... And to be absolutely clear on that, I don’t even have an afterEach hook in any of my tests! Maybe Mocha adds implicit calls to afterEach, when an explicit call to beforeEach exists in the code. However, so long as these implicit calls are not added at the root-level, it does not support my conjecture of hooked code running in the wrong scope to begin with. In short, I’m at a loss here…

By the way, in the code that you linked, there doesn’t seem to be support for the after hook, and I am using this hook in my tests.