feat(dynamic-import-vars): Error when files not found (#1611)

* Add test for throwing if there are no files found

* Throw error if no files were found

* update error message with more context

* chore: update readme and types

---------

Co-authored-by: shellscape <[email protected]>

packages/dynamic-import-vars/README.md

@@ -61,6 +61,13 @@ Default: `[]`
 
 Files to exclude in this plugin (default none).
 
+#### `errorWhenNoFilesFound`
+
+Type: `Boolean`<br>
+Default: `false`
+
+By default, the plugin will not throw errors when target files are not found. Setting this option to true will result in errors thrown when encountering files which don't exist.
+
 #### `warnOnError`
 
 Type: `Boolean`<br>

packages/dynamic-import-vars/src/index.js

@@ -9,7 +9,7 @@ import { createFilter } from '@rollup/pluginutils';
 
 import { dynamicImportToGlob, VariableDynamicImportError } from './dynamic-import-to-glob';
 
-function dynamicImportVariables({ include, exclude, warnOnError } = {}) {
+function dynamicImportVariables({ include, exclude, warnOnError, errorWhenNoFilesFound } = {}) {
   const filter = createFilter(include, exclude);
 
   return {
@@ -55,6 +55,14 @@ function dynamicImportVariables({ include, exclude, warnOnError } = {}) {
               r.startsWith('./') || r.startsWith('../') ? r : `./${r}`
             );
 
+            if (errorWhenNoFilesFound && paths.length === 0) {
+              this.error(
+                new Error(
+                  `No files found in ${glob} when trying to dynamically load concatted string from ${id}`
+                )
+              );
+            }
+
             // create magic string if it wasn't created already
             ms = ms || new MagicString(code);
             // unpack variable dynamic import into a function with import statements per file, rollup

packages/dynamic-import-vars/test/fixtures/fixture-no-files.js

@@ -0,0 +1,3 @@
+export function importModule(name) {
+  return import(`./module-dir-c/${name}.js`);
+}

packages/dynamic-import-vars/test/rollup-plugin-dynamic-import-vars.test.js

@@ -204,3 +204,35 @@ test('dynamic imports assertions', async (t) => {
   );
   t.snapshot(output[0].code);
 });
+
+test("doesn't throw if no files in dir when option isn't set", async (t) => {
+  let thrown = false;
+  try {
+    await rollup({
+      input: 'fixture-no-files.js',
+      plugins: [dynamicImportVars()]
+    });
+  } catch (_) {
+    thrown = true;
+  }
+  t.false(thrown);
+});
+
+test('throws if no files in dir when option is set', async (t) => {
+  let thrown = false;
+  try {
+    await rollup({
+      input: 'fixture-no-files.js',
+      plugins: [dynamicImportVars({ errorWhenNoFilesFound: true })]
+    });
+  } catch (error) {
+    t.deepEqual(
+      error.message,
+      `No files found in ./module-dir-c/*.js when trying to dynamically load concatted string from ${require.resolve(
+        './fixtures/fixture-no-files.js'
+      )}`
+    );
+    thrown = true;
+  }
+  t.true(thrown);
+});

packages/dynamic-import-vars/test/snapshots/rollup-plugin-dynamic-import-vars.test.js.md

@@ -234,3 +234,25 @@ Generated by [AVA](https://avajs.dev).
     ␊
     export { importModule };␊
     `
+
+## no files in dir
+
+> Snapshot 1
+
+    `function __variableDynamicImportRuntime0__(path) {␊
+      switch (path) {␊
+    ␊
+        default: return new Promise(function(resolve, reject) {␊
+          (typeof queueMicrotask === 'function' ? queueMicrotask : setTimeout)(␊
+            reject.bind(null, new Error("Unknown variable dynamic import: " + path))␊
+          );␊
+        })␊
+       }␊
+     }␊
+    ␊
+    function importModule(name) {␊
+      return __variableDynamicImportRuntime0__(\`./module-dir-c/${name}.js\`);␊
+    }␊
+    ␊
+    export { importModule };␊
+    `

packages/dynamic-import-vars/types/index.d.ts

@@ -15,6 +15,12 @@ interface RollupDynamicImportVariablesOptions {
    * By default no files are ignored.
    */
   exclude?: FilterPattern;
+  /**
+   * By default, the plugin will not throw errors when target files are not found.
+   * Setting this option to true will result in errors thrown when encountering files which don't exist.
+   * @default false
+   */
+  errorWhenNoFilesFound?: boolean;
   /**
    * By default, the plugin quits the build process when it encounters an error.
    * If you set this option to true, it will throw a warning instead and leave the code untouched.