feat(yaml): support specifying custom file extensions (#1445)

* make yaml plugin extensions configurable

* prettier

* add tests for extensions option

packages/yaml/src/index.js

@@ -4,13 +4,13 @@ import { createFilter, makeLegalIdentifier } from '@rollup/pluginutils';
 
 const defaults = {
   documentMode: 'single',
-  transform: null
+  transform: null,
+  extensions: ['.yaml', '.yml']
 };
-const ext = /\.ya?ml$/;
 
 export default function yaml(opts = {}) {
   const options = Object.assign({}, defaults, opts);
-  const { documentMode } = options;
+  const { documentMode, extensions } = options;
   const filter = createFilter(options.include, options.exclude);
   let loadMethod = null;
 
@@ -28,7 +28,7 @@ export default function yaml(opts = {}) {
     name: 'yaml',
 
     transform(content, id) {
-      if (!ext.test(id)) return null;
+      if (!extensions.some((ext) => id.toLowerCase().endsWith(ext))) return null;
       if (!filter(id)) return null;
 
       let data = loadMethod(content);

packages/yaml/test/test.js

@@ -98,3 +98,48 @@ test('bad documentMode', async (t) => {
 
   t.throws(exec);
 });
+
+test('file extension not in the list', async (t) => {
+  const content = 'some content';
+  const id = 'testfile.unknown';
+  const plugin = yaml();
+  const output = plugin.transform(content, id);
+
+  t.is(output, null, 'Should return null for unlisted extensions');
+});
+
+test('file passes the filter', async (t) => {
+  const content = 'some content';
+  const id = 'testfile.yaml';
+  const plugin = yaml({ include: '**/*.yaml' });
+  const output = plugin.transform(content, id);
+
+  t.not(output, null, 'Should not return null for files passing the filter');
+});
+
+test('file does not pass the filter', async (t) => {
+  const content = 'some content';
+  const id = 'testfile.yaml';
+  const plugin = yaml({ exclude: '**/*.yaml' });
+  const output = plugin.transform(content, id);
+
+  t.is(output, null, 'Should return null for files not passing the filter');
+});
+
+test('uses custom extensions', async (t) => {
+  const content = 'some content';
+  const id = 'testfile.custom';
+  const plugin = yaml({ extensions: ['.custom'] });
+  const output = plugin.transform(content, id);
+
+  t.not(output, null, 'Should not return null for files with custom extensions');
+});
+
+test('does not process non-custom extensions', async (t) => {
+  const content = 'some content';
+  const id = 'testfile.yaml';
+  const plugin = yaml({ extensions: ['.custom'] });
+  const output = plugin.transform(content, id);
+
+  t.is(output, null, 'Should return null for files without custom extensions');
+});