feat(dynamic-import-vars): Error when no files found

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 +55,12 @@ function dynamicImportVariables({ include, exclude, warnOnError } = {}) {
               r.startsWith('./') || r.startsWith('../') ? r : `./${r}`
             );
 
+            if (errorWhenNoFilesFound && paths.length === 0) {
+              this.error(
+                new Error('No files found when trying to dynamically load concatted string')
+              );
+            }
+
             // 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 +204,29 @@ 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 (_) {
+    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 };␊
+    `