Add inferring of development options from webpack loader mode

Closes GH-2198. Closes GH-2201. Reviewed-by: Christian Murphy <christian.murphy.42@gmail.com> Reviewed-by: Titus Wormer <tituswormer@gmail.com>

Author: remcohaszing

packages/loader/lib/index.js

@@ -35,7 +35,10 @@ const cache = new WeakMap()
 export function loader(value, callback) {
  /** @type {Defaults} */
  const defaults = this.sourceMap ? {SourceMapGenerator} : {}
- const options = /** @type {CompileOptions} */ (this.getOptions())
+ const options = {
+ development: this.mode === 'development',
+ .../** @type {CompileOptions} */ (this.getOptions())
+ }
  const config = {...defaults, ...options}
  const hash = getOptionsHash(options)
  // Some loaders set `undefined` (see `TypeStrong/ts-loader`).

packages/loader/test/index.test.js

@@ -95,6 +95,13 @@ webpack.mdx:1:22: Unexpected end of file in expression, expected a corresponding
  'should compile (react)'
  )
 
+ const reactOutput = await fs.readFile(new URL('react.cjs', base), 'utf8')
+ assert.not.match(
+ reactOutput,
+ /react_jsx_dev_runtime__WEBPACK_IMPORTED_MODULE_\d+__\.jsxDEV/,
+ 'should infer the development option from webpack’s production mode'
+ )
+
  await fs.unlink(new URL('react.cjs', base))
 
  // Preact and source maps
@@ -138,8 +145,15 @@ webpack.mdx:1:22: Unexpected end of file in expression, expected a corresponding
  'should compile (preact)'
  )
 
+ const preactOutput = await fs.readFile(new URL('preact.cjs', base), 'utf8')
+ assert.match(
+ preactOutput,
+ /preact_jsx_dev_runtime__WEBPACK_IMPORTED_MODULE_\d+__\.jsxDEV/,
+ 'should infer the development option from webpack’s development mode'
+ )
+
  assert.match(
- String(await fs.readFile(new URL('preact.cjs', base))),
+ preactOutput,
  /\/\/# sourceMappingURL/,
  'should add a source map if requested'
  )