fix(src): fix plugin run order for fixtures to match tests (#88)

Author: Xunnamius

src/__tests__/plugin-tester.js

@@ -43,6 +43,16 @@ const runPluginTester = async (...args) => {
   }
 }
 
+const pluginWithOrderTracking = (orderArray, orderInt) => () => {
+  return {
+    visitor: {
+      Program() {
+        orderArray.push(orderInt)
+      },
+    },
+  }
+}
+
 beforeEach(() => {
   equalSpy = jest.spyOn(assert, 'equal')
   errorSpy = jest.spyOn(console, 'error').mockImplementation(noop)
@@ -753,6 +763,40 @@ test('appends to root plugins array', async () => {
   expect(programVisitor).toHaveBeenCalledTimes(15)
 })
 
+test('fixtures run plugins in the same order as tests', async () => {
+  const runOrder1 = []
+  const runOrder2 = []
+
+  await runPluginTester(
+    getOptions({
+      plugin: pluginWithOrderTracking(runOrder1, 2),
+      babelOptions: {
+        plugins: [
+          pluginWithOrderTracking(runOrder1, 1),
+          pluginWithOrderTracking(runOrder1, 3),
+        ],
+      },
+    }),
+  )
+
+  await runPluginTester(
+    getOptions({
+      plugin: pluginWithOrderTracking(runOrder2, 2),
+      tests: null,
+      fixtures: getFixturePath('creates-output-file'),
+      babelOptions: {
+        plugins: [
+          pluginWithOrderTracking(runOrder2, 1),
+          pluginWithOrderTracking(runOrder2, 3),
+        ],
+      },
+    }),
+  )
+
+  expect(runOrder1).toStrictEqual([1, 3, 2])
+  expect(runOrder2).toStrictEqual(runOrder1)
+})
+
 test('endOfLine - default', async () => {
   await runPluginTester(
     getOptions({

src/plugin-tester.js

@@ -307,24 +307,28 @@ const createFixtureTests = (fixturesDir, options) => {
         ...rest
       } = options
 
-      const hasBabelrc = [
-        '.babelrc',
-        '.babelrc.js',
-        '.babelrc.cjs',
-      ].some(babelrc => fs.existsSync(path.join(fixtureDir, babelrc)))
+      const hasBabelrc = ['.babelrc', '.babelrc.js', '.babelrc.cjs'].some(
+        babelrc => fs.existsSync(path.join(fixtureDir, babelrc)),
+      )
 
       const {babelOptions} = mergeWith(
         {},
         fullDefaultConfig,
         {
           babelOptions: {
-            plugins: [[plugin, mergedFixtureAndPluginOptions]],
             // if they have a babelrc, then we'll let them use that
             // otherwise, we'll just use our simple config
             babelrc: hasBabelrc,
           },
         },
         rest,
+        {
+          babelOptions: {
+            // Ensure `rest` comes before `babelOptions.plugins` to preserve
+            // default plugin run order
+            plugins: [[plugin, mergedFixtureAndPluginOptions]],
+          },
+        },
         mergeCustomizer,
       )