Truffle: `Truffle test` should allow user to run a specific test using `mocha -g`

[onggunhao]

• [x] I've asked for help in the Truffle Gitter before filing this issue.

Following up from Twitter conversation with @gnidan - ref https://twitter.com/gnidan/status/1136386257481863169

---

Issue

We should have a way to run individual truffle tests, similar to how mocha -g works (greps for a test string).

• There is an alternative way to do this by specifying .only in Mocha tests
• Being able to pass in -g allows us to run specific tests, e.g. in CI

Steps to Reproduce

truffle test -- -g "name of test"

Follow-ups

I'll be working on this, which is similar to issue #7 opened by @oed.

[onggunhao]

@gnidan, I splunked through the codebase. Can I ask for your feedback on developer UX and codebase intuition?

Developer experience

usage:
      "truffle test [<test_file>] [--compile-all] [--network <name>] [--verbose-rpc] [--show-events] **[--grep]**",
    options: [
      {
        option: "--grep",
        description:
          "Only run tests matching this string or regexp, similar to `mocha --grep`"
      },

Implementation

I'm fairly inexperienced with javascript + mocha - so writing the code splunk trail here:

The flow of execution of truffle test is the following (all in truffle-core):
-> cli.js:45 & lib/command.js:110-113: parses args into options object
-> lib/commands/test.js:112: collates config object (:114)
-> lib/test.js:58: creates mocha test with config files (:143). To implement grep, mochaConfig.grep needs to be set to arg values

[eggplantzzz]

@onggunhao I believe you can just use the path to the test file as an argument and it should work. For example truffle test ./test/mySpecificTest.sol.

[eggplantzzz]

@onggunhao Just an FYI, I have a PR out that reworks a lot of the test stuff. It hasn't been merged yet but if might be very relevant to the work you are doing. Check out https://github.com/trufflesuite/truffle/pull/2081

[onggunhao]

@eggplantzzz Ah nice work on #2081! I was actually going to offer more of my sabbatical time to ES6-ify the truffle test package - the callbacks were really weird to follow (esp. the environmentCallback calling run)

I'll probably branch from #2081 and follow up from there. Happy to lend a hand on other tasks - doing this as a way to learn

[eggplantzzz]

Ok great, I'm going to go ahead and try and get it reviewed and merged for the next release.

[GregTheGreek]

Did this ever get worked on? Being able to test a single case is extremely useful in large test files

[eggplantzzz]

@GregTheGreek You should be able to just run one test file by passing the path in as follows:

truffle test ./test/myFavoriteTestFile.js

[AuHau]

Any update on this? Running specific test-file is not enough IMO. When you have tens of tests in a file, only one is failing and you have to rerun the whole suite just for that one test. Especially when you work with time-delays...

[Ankarrr]

Any update on this?

[eggplantzzz]

A workaround you can use is to use only on your test and then feed mocha the specific path to that test.

So you can do

it.only("returns the value I expect", () => {
  const expectedValue = 10;
  ...

And then just run truffle test ./test/myFavoriteTestFile.js

Let me know if you think this workaround is not enough and we can consider a more robust solution.