docs(typescript): More informative error messages (#619)

Co-authored-by: Simon Holthausen <[email protected]>

Author: dummdidumm

packages/typescript/src/options/validate.ts

@@ -44,26 +44,28 @@ export function validatePaths(
 ) {
   if (compilerOptions.out) {
     context.error(
-      `@rollup/plugin-typescript: Deprecated 'out' option is not supported. Use 'outDir' instead.`
+      `@rollup/plugin-typescript: Deprecated Typescript compiler option 'out' is not supported. Use 'outDir' instead.`
     );
   } else if (compilerOptions.outFile) {
     context.error(
-      `@rollup/plugin-typescript: 'outFile' option is not supported. Use 'outDir' instead.`
+      `@rollup/plugin-typescript: Typescript compiler option 'outFile' is not supported. Use 'outDir' instead.`
     );
   }
 
   for (const dirProperty of DIRECTORY_PROPS) {
     if (compilerOptions[dirProperty]) {
       if (!outputOptions.dir) {
         context.error(
-          `@rollup/plugin-typescript: 'dir' must be used when '${dirProperty}' is specified.`
+          `@rollup/plugin-typescript: Rollup 'dir' option must be used when Typescript compiler option '${dirProperty}' is specified.`
         );
       }
 
       // Checks if the given path lies within Rollup output dir
       const fromRollupDirToTs = relative(outputOptions.dir, compilerOptions[dirProperty]!);
       if (fromRollupDirToTs.startsWith('..')) {
-        context.error(`@rollup/plugin-typescript: '${dirProperty}' must be located inside 'dir'.`);
+        context.error(
+          `@rollup/plugin-typescript: Path of Typescript compiler option '${dirProperty}' must be located inside Rollup 'dir' option.`
+        );
       }
     }
   }
@@ -72,21 +74,24 @@ export function validatePaths(
   if (tsBuildInfoPath && compilerOptions.incremental) {
     if (!outputOptions.dir) {
       context.error(
-        `@rollup/plugin-typescript: 'dir' must be used when 'tsBuildInfoFile' or 'incremental' are specified.`
+        `@rollup/plugin-typescript: Rollup 'dir' option must be used when Typescript compiler options 'tsBuildInfoFile' or 'incremental' are specified.`
       );
     }
 
     // Checks if the given path lies within Rollup output dir
     const fromRollupDirToTs = relative(outputOptions.dir, tsBuildInfoPath);
     if (fromRollupDirToTs.startsWith('..')) {
-      context.error(`@rollup/plugin-typescript: 'tsBuildInfoFile' must be located inside 'dir'.`);
+      context.error(
+        `@rollup/plugin-typescript: Path of Typescript compiler option 'tsBuildInfoFile' must be located inside Rollup 'dir' option.`
+      );
     }
   }
 
   if (compilerOptions.declaration || compilerOptions.declarationMap || compilerOptions.composite) {
     if (DIRECTORY_PROPS.every((dirProperty) => !compilerOptions[dirProperty])) {
       context.error(
-        `@rollup/plugin-typescript: 'outDir' or 'declarationDir' must be specified to generate declaration files.`
+        `@rollup/plugin-typescript: You are using one of Typescript's compiler options 'declaration', 'declarationMap' or 'composite'. ` +
+          `In this case 'outDir' or 'declarationDir' must be specified to generate declaration files.`
       );
     }
   }

packages/typescript/test/test.js

@@ -209,15 +209,19 @@ test.serial('ensures outDir is located in Rollup output dir', async (t) => {
     getCode(bundle, { format: 'esm', file: 'fixtures/basic/other/out.js' }, true)
   );
   t.true(
-    noDirError.message.includes(`'dir' must be used when 'outDir' is specified`),
+    noDirError.message.includes(
+      `Rollup 'dir' option must be used when Typescript compiler option 'outDir' is specified`
+    ),
     `Unexpected error message: ${noDirError.message}`
   );
 
   const wrongDirError = await t.throwsAsync(() =>
     getCode(bundle, { format: 'esm', dir: 'fixtures/basic/dist' }, true)
   );
   t.true(
-    wrongDirError.message.includes(`'outDir' must be located inside 'dir'`),
+    wrongDirError.message.includes(
+      `Path of Typescript compiler option 'outDir' must be located inside Rollup 'dir' option`
+    ),
     `Unexpected error message: ${wrongDirError.message}`
   );
 });
@@ -239,15 +243,19 @@ test.serial('ensures declarationDir is located in Rollup output dir', async (t)
     getCode(bundle, { format: 'esm', file: 'fixtures/basic/other/out.js' }, true)
   );
   t.true(
-    noDirError.message.includes(`'dir' must be used when 'declarationDir' is specified`),
+    noDirError.message.includes(
+      `Rollup 'dir' option must be used when Typescript compiler option 'declarationDir' is specified`
+    ),
     `Unexpected error message: ${noDirError.message}`
   );
 
   const wrongDirError = await t.throwsAsync(() =>
     getCode(bundle, { format: 'esm', dir: 'fixtures/basic/dist' }, true)
   );
   t.true(
-    wrongDirError.message.includes(`'declarationDir' must be located inside 'dir'`),
+    wrongDirError.message.includes(
+      `Path of Typescript compiler option 'declarationDir' must be located inside Rollup 'dir' option`
+    ),
     `Unexpected error message: ${wrongDirError.message}`
   );
 });