feat: verify that the package.json fields point to correct path (#401)

### Summary

After initial project setup, it's possible that the location of built
files may diverge from value of package.json fields due to configuration
changes. Previously it'd go unnoticed.

This adds additional checks after the files are built to ensure that
such mismatches cause a build failure.


https://github.com/callstack/react-native-builder-bob/assets/1174278/25d1c427-da3e-4204-b49e-6754c1a316de

### Test plan

- Tested it in React Navigation & React Native Paper repos

Author: satya164

packages/react-native-builder-bob/src/targets/commonjs.ts

@@ -33,5 +33,6 @@ export default async function build({
     output,
     modules: 'commonjs',
     report,
+    field: 'main',
   });
 }

packages/react-native-builder-bob/src/targets/module.ts

@@ -33,5 +33,6 @@ export default async function build({
     output,
     modules: false,
     report,
+    field: 'module',
   });
 }

packages/react-native-builder-bob/src/targets/typescript.ts

@@ -193,16 +193,62 @@ export default async function build({
       report.success(
         `Wrote definition files to ${kleur.blue(path.relative(root, output))}`
       );
+
+      const packageJson = JSON.parse(
+        await fs.readFile(path.join(root, 'package.json'), 'utf-8')
+      );
+
+      if ('types' in packageJson) {
+        if (!packageJson.types.endsWith('.d.ts')) {
+          report.error(
+            `The ${kleur.blue('types')} field in ${kleur.blue(
+              'package.json'
+            )} doesn't point to a definition file. Verify the path points to the correct file under ${kleur.blue(
+              path.relative(root, output)
+            )}.`
+          );
+
+          throw new Error("Found incorrect path in 'types' field.");
+        }
+
+        const typesPath = path.join(root, packageJson.types);
+
+        if (!(await fs.pathExists(typesPath))) {
+          report.error(
+            `The ${kleur.blue('types')} field in ${kleur.blue(
+              'package.json'
+            )} points to a non-existent file: ${kleur.blue(
+              packageJson.types
+            )}.\nVerify the path points to the correct file under ${kleur.blue(
+              path.relative(root, output)
+            )}.`
+          );
+
+          throw new Error("Found incorrect path in 'types' field.");
+        }
+      } else {
+        report.warn(
+          `No ${kleur.blue('types')} field found in ${kleur.blue(
+            'package.json'
+          )}.\nConsider adding it so consumers can use the types.`
+        );
+      }
     } else {
       throw new Error('Failed to build definition files.');
     }
-  } catch (e: any) {
-    if (e.stdout) {
-      report.error(
-        `Errors found when building definition files:\n${e.stdout.toString()}`
-      );
+  } catch (e: unknown) {
+    if (e != null && typeof e === 'object') {
+      if ('stdout' in e && e.stdout != null) {
+        report.error(
+          `Errors found when building definition files:\n${e.stdout.toString()}`
+        );
+      } else if ('message' in e && typeof e.message === 'string') {
+        report.error(e.message);
+      } else {
+        throw e;
+      }
     } else {
-      report.error(e.message);
+      throw e;
     }
 
     throw new Error('Failed to build definition files.');

packages/react-native-builder-bob/src/utils/compile.ts

@@ -12,6 +12,7 @@ type Options = Input & {
   sourceMaps?: boolean;
   copyFlow?: boolean;
   modules: 'commonjs' | false;
+  field: 'main' | 'module';
 };
 
 export default async function compile({
@@ -24,6 +25,7 @@ export default async function compile({
   copyFlow,
   sourceMaps = true,
   report,
+  field,
 }: Options) {
   const files = glob.sync('**/*', {
     cwd: source,
@@ -120,4 +122,43 @@ export default async function compile({
   );
 
   report.success(`Wrote files to ${kleur.blue(path.relative(root, output))}`);
+
+  const packageJson = JSON.parse(
+    await fs.readFile(path.join(root, 'package.json'), 'utf-8')
+  );
+
+  if (field in packageJson) {
+    try {
+      require.resolve(path.join(root, packageJson[field]));
+    } catch (e: unknown) {
+      if (
+        e != null &&
+        typeof e === 'object' &&
+        'code' in e &&
+        e.code === 'MODULE_NOT_FOUND'
+      ) {
+        report.error(
+          `The ${kleur.blue(field)} field in ${kleur.blue(
+            'package.json'
+          )} points to a non-existent file: ${kleur.blue(
+            packageJson[field]
+          )}.\nVerify the path points to the correct file under ${kleur.blue(
+            path.relative(root, output)
+          )}.`
+        );
+
+        throw new Error(`Found incorrect path in '${field}' field.`);
+      }
+
+      throw e;
+    }
+  } else {
+    report.warn(
+      `No ${kleur.blue(field)} field found in ${kleur.blue(
+        'package.json'
+      )}. Add it to your ${kleur.blue(
+        'package.json'
+      )} so that consumers of your package can use it.`
+    );
+  }
 }

packages/react-native-builder-bob/src/utils/logger.ts

@@ -3,7 +3,16 @@ import kleur from 'kleur';
 const logger =
   (type: string, color: Function) =>
   (...messages: unknown[]) => {
-    console.log(color(kleur.bold(type)), ...messages);
+    console.log(
+      color(kleur.bold(type)),
+      ...messages.map((message) => {
+        if (typeof message === 'string') {
+          return message.split('\n').join(`\n  `);
+        } else {
+          return message;
+        }
+      })
+    );
   };
 
 export const info = logger('ℹ', kleur.blue);