fix(preview-server): compatibility checker can't find config when inlining pixel based preset (#2351)

.changeset/kind-experts-vanish.md

@@ -0,0 +1,5 @@
+---
+"@react-email/preview-server": patch
+---
+
+improved method of resolving tailwind configs when checking compatibility

packages/preview-server/src/utils/caniemail/tailwind/get-tailwind-config.spec.ts

@@ -0,0 +1,44 @@
+import { promises as fs } from 'node:fs';
+import path from 'node:path';
+import { parse } from '@babel/parser';
+import { pixelBasedPreset } from '@react-email/components';
+import { getTailwindConfig } from './get-tailwind-config';
+
+describe('getTailwindConfig()', () => {
+  it("should work on the demo's Vercel Invite template", async () => {
+    const sourcePath = path.resolve(
+      __dirname,
+      '../../../../../../apps/demo/emails/notifications/vercel-invite-user.tsx',
+    );
+    const sourceCode = await fs.readFile(sourcePath, 'utf8');
+    const ast = parse(sourceCode, {
+      strictMode: false,
+      errorRecovery: true,
+      sourceType: 'unambiguous',
+      plugins: ['jsx', 'typescript', 'decorators'],
+    });
+
+    expect(await getTailwindConfig(sourceCode, ast, sourcePath)).toEqual({
+      presets: [pixelBasedPreset],
+    });
+  });
+
+  it('should work with email templates that import the tailwind config', async () => {
+    const sourcePath = path.resolve(
+      __dirname,
+      './tests/dummy-email-template.tsx',
+    );
+    const sourceCode = await fs.readFile(sourcePath, 'utf8');
+    const ast = parse(sourceCode, {
+      strictMode: false,
+      errorRecovery: true,
+      sourceType: 'unambiguous',
+      plugins: ['jsx', 'typescript', 'decorators'],
+    });
+
+    expect(await getTailwindConfig(sourceCode, ast, sourcePath)).toEqual({
+      theme: {},
+      presets: [pixelBasedPreset],
+    });
+  });
+});

packages/preview-server/src/utils/caniemail/tailwind/get-tailwind-config.ts

@@ -2,8 +2,10 @@ import path from 'node:path';
 import type { Node } from '@babel/traverse';
 import traverse from '@babel/traverse';
 import * as esbuild from 'esbuild';
+import type { RawSourceMap } from 'source-map-js';
 import type { Config as TailwindOriginalConfig } from 'tailwindcss';
 import type { AST } from '../../../actions/email-validation/check-compatibility';
+import { improveErrorWithSourceMap } from '../../improve-error-with-sourcemap';
 import { isErr } from '../../result';
 import { runBundledCode } from '../../run-bundled-code';
 
@@ -23,8 +25,6 @@ export type TailwindConfig = Pick<
   | 'plugins'
 >;
 
-type ImportDeclaration = Node & { type: 'ImportDeclaration' };
-
 export const getTailwindConfig = async (
   sourceCode: string,
   ast: AST,
@@ -33,35 +33,23 @@ export const getTailwindConfig = async (
   const configAttribute = getTailwindConfigNode(ast);
 
   if (configAttribute) {
-    const configIdentifierName =
-      configAttribute.value?.type === 'JSXExpressionContainer' &&
-      configAttribute.value.expression.type === 'Identifier'
-        ? configAttribute.value.expression.name
-        : undefined;
-    if (configIdentifierName) {
-      const tailwindConfigImport = getImportWithGivenDefaultSpecifier(
-        ast,
-        configIdentifierName,
-      );
-      if (tailwindConfigImport) {
-        return getConfigFromImport(tailwindConfigImport, sourcePath);
-      }
-    }
-
-    const configObjectExpression =
-      configAttribute.value?.type === 'JSXExpressionContainer' &&
-      configAttribute.value.expression.type === 'ObjectExpression'
+    const configExpressionValue =
+      configAttribute.value?.type === 'JSXExpressionContainer'
         ? configAttribute.value.expression
         : undefined;
-    if (configObjectExpression?.start && configObjectExpression.end) {
-      const configObjectSourceCode = sourceCode.slice(
-        configObjectExpression.start,
-        configObjectExpression.end,
+    if (configExpressionValue?.start && configExpressionValue.end) {
+      const configSourceValue = sourceCode.slice(
+        configExpressionValue.start,
+        configExpressionValue.end,
       );
 
       try {
-        const getConfig = new Function(`return ${configObjectSourceCode}`);
-        return getConfig() as TailwindConfig;
+        return getConfigFromCode(
+          `${sourceCode}
+
+const reactEmailTailwindConfigInternal = ${configSourceValue};`,
+          sourcePath,
+        );
       } catch (exception) {
         console.warn(exception);
         console.warn(
@@ -74,80 +62,77 @@ export const getTailwindConfig = async (
   return {};
 };
 
-const getConfigFromImport = async (
-  tailwindConfigImport: ImportDeclaration,
-  sourcePath: string,
+const getConfigFromCode = async (
+  code: string,
+  filepath: string,
 ): Promise<TailwindConfig> => {
-  const configRelativePath = tailwindConfigImport.source.value;
-  const sourceDirpath = path.dirname(sourcePath);
-  const configFilepath = path.join(sourceDirpath, configRelativePath);
+  const configDirpath = path.dirname(filepath);
 
   const configBuildResult = await esbuild.build({
     bundle: true,
     stdin: {
-      contents: `import tailwindConfig from "${configRelativePath}"; 
-export { tailwindConfig };`,
+      contents: `${code} 
+export { reactEmailTailwindConfigInternal };`,
+      sourcefile: filepath,
       loader: 'tsx',
-      resolveDir: path.dirname(sourcePath),
+      resolveDir: configDirpath,
     },
     platform: 'node',
+    sourcemap: 'external',
+    jsx: 'automatic',
+    outdir: 'stdout', // just a stub for esbuild, it won't actually write to this folder
     write: false,
     format: 'cjs',
     logLevel: 'silent',
   });
-  const configFile = configBuildResult.outputFiles[0];
+  const sourceMapFile = configBuildResult.outputFiles[0]!;
+  const configFile = configBuildResult.outputFiles[1];
   if (configFile === undefined) {
     throw new Error(
       'Could not build config file as it was found as undefined, this is most likely a bug, please open an issue.',
     );
   }
-  const configModule = runBundledCode(configFile.text, configFilepath);
+
+  const configModule = runBundledCode(configFile.text, filepath);
   if (isErr(configModule)) {
-    throw new Error(
-      `Error when trying to run the config file: ${configModule.error}`,
+    const sourceMap = JSON.parse(sourceMapFile.text) as RawSourceMap;
+    // because it will have a path like <tsconfigLocation>/stdout/email.js.map
+    sourceMap.sourceRoot = path.resolve(sourceMapFile.path, '../..');
+    sourceMap.sources = sourceMap.sources.map((source) =>
+      path.resolve(sourceMapFile.path, '..', source),
     );
+    const errorObject = improveErrorWithSourceMap(
+      configModule.error as Error,
+      filepath,
+      sourceMap,
+    );
+    const error = new Error();
+    error.name = errorObject.name;
+    error.message = errorObject.message;
+    error.stack = errorObject.stack;
+    throw error;
   }
 
   if (
     typeof configModule.value === 'object' &&
     configModule.value !== null &&
-    'tailwindConfig' in configModule.value
+    'reactEmailTailwindConfigInternal' in configModule.value
   ) {
-    return configModule.value.tailwindConfig as TailwindConfig;
+    return configModule.value
+      .reactEmailTailwindConfigInternal as TailwindConfig;
   }
 
   throw new Error(
-    `Could not read Tailwind config at ${configFilepath} because it doesn't have a default export in it.`,
+    'Could not get the Tailwind config, this is likely a bug, please file an issue.',
     {
       cause: {
         configModule,
-        configFilepath,
+        configFilepath: filepath,
       },
     },
   );
 };
 
-const getImportWithGivenDefaultSpecifier = (
-  ast: AST,
-  specifierName: string,
-) => {
-  let importNode: ImportDeclaration | undefined;
-  traverse(ast, {
-    ImportDeclaration(nodePath) {
-      if (
-        nodePath.node.specifiers.some(
-          (specifier) =>
-            specifier.type === 'ImportDefaultSpecifier' &&
-            specifier.local.name === specifierName,
-        )
-      ) {
-        importNode = nodePath.node;
-      }
-    },
-  });
-  return importNode;
-};
-
 type JSXAttribute = Node & { type: 'JSXAttribute' };
 
 const getTailwindConfigNode = (ast: AST) => {

packages/preview-server/src/utils/caniemail/tailwind/tests/dummy-email-template.tsx

@@ -0,0 +1,10 @@
+import { Tailwind } from '@react-email/components';
+import tailwindConfig from './tailwind.config';
+
+export default function EmailTemplate() {
+  return (
+    <Tailwind config={tailwindConfig}>
+      <div className="bg-red-400 w-20" />
+    </Tailwind>
+  );
+}

packages/preview-server/src/utils/caniemail/tailwind/tests/tailwind.config.ts

@@ -0,0 +1,6 @@
+import { pixelBasedPreset, type TailwindConfig } from '@react-email/components';
+
+export default {
+  theme: {},
+  presets: [pixelBasedPreset],
+} satisfies TailwindConfig;