From ea981008794e10c32b912ba3be53f58bbd3a868a Mon Sep 17 00:00:00 2001
From: Remco Haszing <remcohaszing@gmail.com>
Date: Fri, 23 Dec 2022 15:04:28 +0100
Subject: [PATCH 1/2] Infer development option from Webpack mode

Closes #2198
---
 packages/loader/lib/index.js       | 5 ++++-
 packages/loader/test/index.test.js | 6 ++++++
 2 files changed, 10 insertions(+), 1 deletion(-)

diff --git a/packages/loader/lib/index.js b/packages/loader/lib/index.js
index db1e3f1c2..aad7c5b05 100644
--- a/packages/loader/lib/index.js
+++ b/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`).
diff --git a/packages/loader/test/index.test.js b/packages/loader/test/index.test.js
index 176201207..470ddb80f 100644
--- a/packages/loader/test/index.test.js
+++ b/packages/loader/test/index.test.js
@@ -138,6 +138,12 @@ webpack.mdx:1:22: Unexpected end of file in expression, expected a corresponding
     'should compile (preact)'
   )
 
+  assert.ok(
+    // @ts-expect-error Type definitions don’t define __source.
+    modPreact.default.default({}).__source,
+    'should infer the development option from webpack’s mode'
+  )
+
   assert.match(
     String(await fs.readFile(new URL('preact.cjs', base))),
     /\/\/# sourceMappingURL/,

From e39eda8ef0a967967ae23d3b3dd545926ac33434 Mon Sep 17 00:00:00 2001
From: Remco Haszing <remcohaszing@gmail.com>
Date: Mon, 26 Dec 2022 16:01:29 +0100
Subject: [PATCH 2/2] Use output match to detect dev mode in webpack bundle

---
 packages/loader/test/index.test.js | 18 +++++++++++++-----
 1 file changed, 13 insertions(+), 5 deletions(-)

diff --git a/packages/loader/test/index.test.js b/packages/loader/test/index.test.js
index 470ddb80f..9f8593085 100644
--- a/packages/loader/test/index.test.js
+++ b/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
@@ -138,14 +145,15 @@ webpack.mdx:1:22: Unexpected end of file in expression, expected a corresponding
     'should compile (preact)'
   )
 
-  assert.ok(
-    // @ts-expect-error Type definitions don’t define __source.
-    modPreact.default.default({}).__source,
-    'should infer the development option from webpack’s mode'
+  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'
   )