Preact support?

[JamesMcMahon]

Currently, chai-enzyme doesn't work with the Preact library.

It fails with the stack trace:

Error: Cannot find module 'react'
    at Function.Module._resolveFilename (internal/modules/cjs/loader.js:636:15)
    at Function.Module._load (internal/modules/cjs/loader.js:562:25)
    at Module.require (internal/modules/cjs/loader.js:692:17)
    at require (internal/modules/cjs/helpers.js:25:18)
    at Object.<anonymous> (/Users/james/workspace/dna-info/widget/node_modules/chai-enzyme/build/reactNodeToString.js:8:14)
    at Module._compile (internal/modules/cjs/loader.js:778:30)
    at Object.Module._extensions..js (internal/modules/cjs/loader.js:789:10)
    at Module.load (internal/modules/cjs/loader.js:653:32)
    at tryModuleLoad (internal/modules/cjs/loader.js:593:12)
    at Function.Module._load (internal/modules/cjs/loader.js:585:3)
    at Module.require (internal/modules/cjs/loader.js:692:17)
    at require (internal/modules/cjs/helpers.js:25:18)
    at Object.<anonymous> (/Users/james/workspace/dna-info/widget/node_modules/chai-enzyme/build/assertions/contain.js:8:26)
    at Module._compile (internal/modules/cjs/loader.js:778:30)
    at Object.Module._extensions..js (internal/modules/cjs/loader.js:789:10)
    at Module.load (internal/modules/cjs/loader.js:653:32)
    at tryModuleLoad (internal/modules/cjs/loader.js:593:12)
    at Function.Module._load (internal/modules/cjs/loader.js:585:3)
    at Module.require (internal/modules/cjs/loader.js:692:17)
    at require (internal/modules/cjs/helpers.js:25:18)
    at Object.<anonymous> (/Users/james/workspace/dna-info/widget/node_modules/chai-enzyme/build/index.js:15:16)
    at Module._compile (internal/modules/cjs/loader.js:778:30)
    at Object.Module._extensions..js (internal/modules/cjs/loader.js:789:10)
    at Module.load (internal/modules/cjs/loader.js:653:32)
    at tryModuleLoad (internal/modules/cjs/loader.js:593:12)
    at Function.Module._load (internal/modules/cjs/loader.js:585:3)
    at Module.require (internal/modules/cjs/loader.js:692:17)
    at require (internal/modules/cjs/helpers.js:25:18)
    at Object.<anonymous> (/Users/james/workspace/dna-info/widget/tests/ChartComponent.spec.tsx:5:1)
    at Module._compile (internal/modules/cjs/loader.js:778:30)
    at Module.m._compile (/Users/james/workspace/dna-info/widget/node_modules/ts-node/src/index.ts:473:23)
    at Module._extensions..js (internal/modules/cjs/loader.js:789:10)
    at Object.require.extensions.(anonymous function) [as .tsx] (/Users/james/workspace/dna-info/widget/node_modules/ts-node/src/index.ts:476:12)
    at Module.load (internal/modules/cjs/loader.js:653:32)
    at tryModuleLoad (internal/modules/cjs/loader.js:593:12)
    at Function.Module._load (internal/modules/cjs/loader.js:585:3)
    at Module.require (internal/modules/cjs/loader.js:692:17)
    at require (internal/modules/cjs/helpers.js:25:18)
    at /Users/james/workspace/dna-info/widget/node_modules/mocha/lib/mocha.js:334:36
    at Array.forEach (<anonymous>)
    at Mocha.loadFiles (/Users/james/workspace/dna-info/widget/node_modules/mocha/lib/mocha.js:331:14)
    at Mocha.run (/Users/james/workspace/dna-info/widget/node_modules/mocha/lib/mocha.js:811:10)
    at Object.exports.singleRun (/Users/james/workspace/dna-info/widget/node_modules/mocha/lib/cli/run-helpers.js:108:16)
    at exports.runMocha (/Users/james/workspace/dna-info/widget/node_modules/mocha/lib/cli/run-helpers.js:142:13)
    at Object.exports.handler.argv [as handler] (/Users/james/workspace/dna-info/widget/node_modules/mocha/lib/cli/run.js:292:3)
    at Object.runCommand (/Users/james/workspace/dna-info/widget/node_modules/mocha/node_modules/yargs/lib/command.js:242:26)
    at Object.parseArgs [as _parseArgs] (/Users/james/workspace/dna-info/widget/node_modules/mocha/node_modules/yargs/yargs.js:1087:28)
    at Object.parse (/Users/james/workspace/dna-info/widget/node_modules/mocha/node_modules/yargs/yargs.js:566:25)
    at Object.exports.main (/Users/james/workspace/dna-info/widget/node_modules/mocha/lib/cli/cli.js:68:6)
    at Object.<anonymous> (/Users/james/workspace/dna-info/widget/node_modules/mocha/bin/mocha:154:29)
    at Module._compile (internal/modules/cjs/loader.js:778:30)
    at Object.Module._extensions..js (internal/modules/cjs/loader.js:789:10)
    at Module.load (internal/modules/cjs/loader.js:653:32)
    at tryModuleLoad (internal/modules/cjs/loader.js:593:12)
    at Function.Module._load (internal/modules/cjs/loader.js:585:3)
    at Function.Module.runMain (internal/modules/cjs/loader.js:831:12)
    at startup (internal/bootstrap/node.js:283:19)
    at bootstrapNodeJSCore (internal/bootstrap/node.js:622:3)

With the issue coming from the React import in reactNodeToString.js.

I haven't looked deeply into this, but I was wondering if it was possible to decouple this library from React and be able to use a library like Preact.

[ljharb]

The only way i can see that it would really be generalizeable is if it imported all react-specific things from the configured enzyme adapter - that way, a preact adapter could supply whatever functionality was needed.

[JamesMcMahon]

The only way i can see that it would really be generalizeable is if it imported all react-specific things from the configured enzyme adapter - that way, a preact adapter could supply whatever functionality was needed.

Yeah, I was thinking the same. Not sure what is involved there, I need to take some time to look at how some of their other adaptors work.

Would you be open to a pull request?

BTW, the work around is to install React as a dev dependency. So far everything works when I do that.

[javidjamae]

@JamesMcMahon said:

BTW, the work around is to install React as a dev dependency. So far everything works when I do that.

I can confirm that merely adding react as a dev dependency got past this error:
yarn add react --dev

I'm not sure if there are any possible discrepancies between how react and preact might cause enzyme to render the components. This could cause some tests to be less reliable. But, at least the workaround allows me to have tests, so I can't complain too much. 😄