Fix resolve base in esbuild loader (#1854)

Closes GH-1821.
Related-to: wooorm/xdm@db74ddc

packages/esbuild/lib/index.js

@@ -13,8 +13,10 @@
  * @typedef {ProcessorOptions & {allowDangerousRemoteMdx?: boolean}} Options
  */
 
-import {promises as fs} from 'fs'
-import process from 'process'
+import assert from 'node:assert'
+import {promises as fs} from 'node:fs'
+import path from 'node:path'
+import process from 'node:process'
 import {URL} from 'url'
 import got from 'got'
 import {VFile} from 'vfile'
@@ -49,6 +51,7 @@ export function esbuild(options = {}) {
     const filter = extnamesToRegex(extnames)
     /* eslint-disable-next-line security/detect-non-literal-regexp */
     const filterHttp = new RegExp('^https?:\\/{2}.+' + filter.source)
+    const http = /^https?:\/{2}/
     const filterHttpOrRelative = /^(https?:\/{2}|.{1,2}\/).*/
 
     if (allowDangerousRemoteMdx) {
@@ -205,9 +208,19 @@ export function esbuild(options = {}) {
         })
       }
 
+      // Safety check: the file has a path, so there has to be a `dirname`.
+      assert(file.dirname, 'expected `dirname` to be defined')
+
       // V8 on Erbium.
-      /* c8 ignore next 2 */
-      return {contents: value, errors, warnings, resolveDir: p.cwd()}
+      /* c8 ignore next 9 */
+      return {
+        contents: value,
+        errors,
+        warnings,
+        resolveDir: http.test(file.path)
+          ? p.cwd()
+          : path.resolve(file.cwd, file.dirname)
+      }
     }
   }
 }

packages/esbuild/test/index.test.js

@@ -45,6 +45,45 @@ test('@mdx-js/esbuild', async () => {
   await fs.unlink(new URL('./esbuild.mdx', import.meta.url))
   await fs.unlink(new URL('./esbuild.js', import.meta.url))
 
+  // Resolve directory.
+  await fs.writeFile(
+    new URL('./esbuild-resolve.mdx', import.meta.url),
+    'import Content from "./folder/file.mdx"\n\n<Content/>'
+  )
+  await fs.mkdir(new URL('./folder', import.meta.url))
+  await fs.writeFile(
+    new URL('./folder/file.mdx', import.meta.url),
+    'import {data} from "./file.js"\n\n{data}'
+  )
+  await fs.writeFile(
+    new URL('./folder/file.js', import.meta.url),
+    'export const data = 0.1'
+  )
+  await esbuild.build({
+    bundle: true,
+    define: {'process.env.NODE_ENV': '"development"'},
+    entryPoints: [
+      fileURLToPath(new URL('./esbuild-resolve.mdx', import.meta.url))
+    ],
+    outfile: fileURLToPath(new URL('./esbuild-resolve.js', import.meta.url)),
+    format: 'esm',
+    plugins: [esbuildMdx()]
+  })
+  /** @type {MDXContent} */
+  Content =
+    /* @ts-expect-error file is dynamically generated */
+    (await import('./esbuild-resolve.js')).default // type-coverage:ignore-line
+
+  assert.equal(
+    renderToStaticMarkup(React.createElement(Content)),
+    '0.1',
+    'should compile'
+  )
+
+  await fs.unlink(new URL('./esbuild-resolve.mdx', import.meta.url))
+  await fs.unlink(new URL('./esbuild-resolve.js', import.meta.url))
+  await fs.rmdir(new URL('./folder/', import.meta.url), {recursive: true})
+
   // Markdown.
   await fs.writeFile(new URL('./esbuild.md', import.meta.url), '\ta')
 
@@ -337,8 +376,6 @@ test('@mdx-js/esbuild', async () => {
 
   await fs.unlink(new URL('./esbuild-warnings.mdx', import.meta.url))
 
-  console.log('\nnote: the preceding errors and warnings are expected!\n')
-
   await fs.writeFile(
     new URL('./esbuild-plugin-crash.mdx', import.meta.url),
     '# hi'
@@ -466,7 +503,7 @@ test('@mdx-js/esbuild', async () => {
   // Remote markdown.
   await fs.writeFile(
     new URL('./esbuild-with-remote-md.mdx', import.meta.url),
-    'import Content from "https://raw.githubusercontent.com/wooorm/xdm/main/test/files/md-file.md"\n\n<Content />'
+    'import Content from "https://raw.githubusercontent.com/mdx-js/mdx/main/packages/esbuild/test/files/md-file.md"\n\n<Content />'
   )
 
   await esbuild.build({
@@ -498,7 +535,7 @@ test('@mdx-js/esbuild', async () => {
   // Remote MDX importing more markdown.
   await fs.writeFile(
     new URL('./esbuild-with-remote-mdx.mdx', import.meta.url),
-    'import Content from "https://raw.githubusercontent.com/wooorm/xdm/main/test/files/mdx-file-importing-markdown.mdx"\n\n<Content />'
+    'import Content from "https://raw.githubusercontent.com/mdx-js/mdx/main/packages/esbuild/test/files/mdx-file-importing-markdown.mdx"\n\n<Content />'
   )
 
   await esbuild.build({

packages/mdx/lib/condition.js

@@ -1,3 +1,3 @@
-import process from 'node:process'
+import process from 'process'
 
 export const development = process.env.NODE_ENV === 'development'