swc-node

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Running Node v16@latest. @swc-node/register doesn't work with Ava out of the box. The instructions in the README aren't comprehensive enough to use straight away.

config:

  "ava": {
    "extensions": ["ts"],
    "require": ["@swc-node/register"],
    "files": ["!**/fixtures/**", "!**/helpers/**", "!**/recipes/**", "!**/types.ts"]
  }

test:

import test from 'ava';

import * as tools from '../src';

test('exports', (t) => {
  t.snapshot(tools);
});

result:

  Uncaught exception in test/test.ts

  SyntaxError: Cannot use import statement outside a module

  › Module._compile (/Users/code/packages/node_modules/.pnpm/[email protected]/node_modules/pirates/lib/index.js:136:24)
  › newLoader (/Users/code/packages/node_modules/.pnpm/[email protected]/node_modules/pirates/lib/index.js:141:7)

  ✖ test/test.ts exited with a non-zero exit code: 1

Now, I understand that error message has to do with ESM module support. OK. I'll tell it to use a tsconfig that should work around that:

tsconfig.base.json:

{
  "compilerOptions": {
    "allowSyntheticDefaultImports": true,
    "declaration": true,
    "emitDecoratorMetadata": true,
    "esModuleInterop": true,
    "experimentalDecorators": true,
    "lib": ["ES2018", "ES2020", "esnext.asynciterable", "dom"],
    "module": "commonjs",
    "moduleResolution": "node",
    "noEmitOnError": false,
    "noUnusedLocals": true,
    "noUnusedParameters": true,
    "pretty": true,
    "removeComments": true,
    "resolveJsonModule": true,
    "skipLibCheck": true,
    "sourceMap": true,
    "strict": true,
    "target": "es2020",
    "useUnknownInCatchVariables": false
  },
  "exclude": ["dist", "node_modules", "test/types"]
}

tsconfig.json (used by test):

{
  "compilerOptions": {
    "outDir": "dist"
  },
  "extends": "../../shared/tsconfig.base.json",
  "include": ["src", "bin/*", "test"]
}

updated config:

  "ava": {
    "extensions": ["ts"],
    "require": ["@swc-node/register"],
    "files": ["!**/fixtures/**", "!**/helpers/**", "!**/recipes/**", "!**/types.ts"],
    "environmentVariables": {
      "SWC_NODE_PROJECT": "./tsconfig.json"
    }
  }

Same result. If I swap ts-node/register back in, everything works again. There's either a bit of information left out, or this straight up does not work with Ava. I'd be baffled if it was the latter because I can see tests working here in this repo and they use ava.

Are you trying to setup this for ESM or CJS?

If for ESM, then AVA needs different setup. Here's my config:

export default {
  environmentVariables: {
    SWC_NODE_PROJECT: "./tsconfig.ava.json", // This one is not necessary, just my default tsconfig.json ignores tests, so swc-node will not compile them. This file just adds tests to `include` section of the config.
    SWCRC: "true"
  },
  extensions: {
    ts: "module"
  },
  nodeArguments: [
    "--no-warnings",
    "--loader=@swc-node/register/esm" // This is the one loader you need instead of swc-node/register
  ],
  files: [
    "src/**/*.test.ts"
  ]
}

Worth to mention that this will not work on Node v20, because nodeArguments are getting ignored for some reason. To fix this, you'll need to move them to package.json

  "scripts": {
    "test": "cross-env NODE_OPTIONS=\"--no-warnings --loader=@swc-node/register/esm\" ava --fail-fast"
  },

Also, I'm not sure if .swcrc would be necessary, probably not, but I have one in my project:

{
  "$schema": "https://json.schemastore.org/swcrc",
  "jsc": {
    "parser": {
      "syntax": "typescript"
    },
    "target": "es2020"
  }
}

Hope this will help.