chore(tasks/transform-conformance): support override to replace `ta…

…keover` mode (#7771)

This PR does the following things.

1. Move the override output of the `snapshots` folder to the `overrides` folder.
2. Support `override` mode to replace `takeover` mode
3. The `update_fixtures.js` no longer uses `overrides`'s `output.js` to replace Babel's `output.js`.

### How does `override` mode work?

When running each test, it checks whether an output file for that test exists in the ⁠`overrides` directory. If it does, the output file will be used to compare with the transformed code.

.typos.toml

@@ -23,7 +23,7 @@ extend-exclude = [
   "tasks/prettier_conformance/prettier",
   "tasks/prettier_conformance/snapshots",
   "tasks/transform_conformance/tests/**/output.js",
-  "tasks/transform_conformance/snapshots",
+  "tasks/transform_conformance/overrides",
   "npm/oxc-wasm/oxc_wasm.js",
 ]
 

tasks/transform_conformance/src/constants.rs

@@ -105,6 +105,3 @@ pub const SKIP_TESTS: &[&str] = &[
     "babel-plugin-transform-object-rest-spread/test/fixtures/object-rest/remove-unused-excluded-keys-loose",
     "babel-plugin-transform-object-rest-spread/test/fixtures/object-rest/regression/gh-8323"
 ];
-
-pub const SNAPSHOT_TESTS: &[&str] =
-    &["babel-plugin-transform-object-rest-spread", "babel-plugin-transform-optional-chaining"];

tasks/transform_conformance/src/lib.rs

@@ -51,6 +51,10 @@ fn snap_root() -> PathBuf {
     conformance_root().join("snapshots")
 }
 
+fn override_root() -> PathBuf {
+    conformance_root().join("overrides")
+}
+
 fn oxc_test_root() -> PathBuf {
     conformance_root().join("tests")
 }

tasks/transform_conformance/src/test_case.rs

@@ -16,9 +16,9 @@ use oxc::{
 use oxc_tasks_common::{normalize_path, print_diff_in_terminal, project_root};
 
 use crate::{
-    constants::{PLUGINS_NOT_SUPPORTED_YET, SKIP_TESTS, SNAPSHOT_TESTS},
+    constants::{PLUGINS_NOT_SUPPORTED_YET, SKIP_TESTS},
     driver::Driver,
-    fixture_root, oxc_test_root, packages_root, snap_root, TestRunnerOptions,
+    fixture_root, override_root, oxc_test_root, packages_root, TestRunnerOptions,
 };
 
 #[derive(Debug)]
@@ -35,12 +35,19 @@ pub struct TestCase {
 pub enum TestCaseKind {
     Conformance,
     Exec,
-    Snapshot,
 }
 
 impl TestCase {
     pub fn new(cwd: &Path, path: &Path) -> Option<Self> {
-        let mut options = BabelOptions::from_test_path(path.parent().unwrap());
+        let mut options_directory_path = path.parent().unwrap().to_path_buf();
+        // Try to find the override options.json
+        if let Some(path) = Self::convert_to_override_path(options_directory_path.as_path()) {
+            if path.join("options.json").exists() {
+                options_directory_path = path;
+            }
+        }
+
+        let mut options = BabelOptions::from_test_path(options_directory_path.as_path());
         options.cwd.replace(cwd.to_path_buf());
         let transform_options = TransformOptions::try_from(&options);
         let path = path.to_path_buf();
@@ -59,14 +66,7 @@ impl TestCase {
         else if path.file_stem().is_some_and(|name| name == "input" || name == "input.d")
             && path.extension().is_some_and(|ext| VALID_EXTENSIONS.contains(&ext.to_str().unwrap()))
         {
-            if path
-                .strip_prefix(packages_root())
-                .is_ok_and(|p| SNAPSHOT_TESTS.iter().any(|t| p.to_string_lossy().starts_with(t)))
-            {
-                TestCaseKind::Snapshot
-            } else {
-                TestCaseKind::Conformance
-            }
+            TestCaseKind::Conformance
         } else {
             return None;
         };
@@ -96,6 +96,28 @@ impl TestCase {
         source_type
     }
 
+    fn convert_to_override_path(path: &Path) -> Option<PathBuf> {
+        path.strip_prefix(packages_root()).ok().map(|p| override_root().join(p))
+    }
+
+    fn get_output_path(&self) -> Option<PathBuf> {
+        let babel_output_path =
+            self.path.parent().unwrap().read_dir().unwrap().find_map(|entry| {
+                let path = entry.ok()?.path();
+                let file_stem = path.file_stem()?;
+                (file_stem == "output").then_some(path)
+            })?;
+
+        // Try to find the override output path
+        if let Some(output_path) = Self::convert_to_override_path(&babel_output_path) {
+            if output_path.exists() {
+                return Some(output_path);
+            }
+        }
+
+        Some(babel_output_path)
+    }
+
     pub fn skip_test_case(&self) -> bool {
         let options = &self.options;
 
@@ -203,17 +225,12 @@ impl TestCase {
                     self.test_exec(filtered);
                 }
             }
-            TestCaseKind::Snapshot => self.test_snapshot(filtered),
         }
     }
 
     /// Test conformance by comparing the parsed babel code and transformed code.
     fn test_conformance(&mut self, filtered: bool) {
-        let output_path = self.path.parent().unwrap().read_dir().unwrap().find_map(|entry| {
-            let path = entry.ok()?.path();
-            let file_stem = path.file_stem()?;
-            (file_stem == "output").then_some(path)
-        });
+        let output_path = self.get_output_path();
 
         let allocator = Allocator::default();
         let input = fs::read_to_string(&self.path).unwrap();
@@ -388,29 +405,6 @@ test("exec", () => {{
 }})"#
         )
     }
-
-    fn test_snapshot(&self, filtered: bool) {
-        let result = match self.transform(HelperLoaderMode::External) {
-            Ok(code) => code,
-            Err(error) => error,
-        };
-        let mut path = snap_root().join(self.path.strip_prefix(packages_root()).unwrap());
-        path.set_file_name("output");
-        let input_extension = self.path.extension().unwrap().to_str().unwrap();
-        let extension =
-            input_extension.chars().map(|c| if c == 't' { 'j' } else { c }).collect::<String>();
-        path.set_extension(extension);
-        if filtered {
-            println!("Input path: {:?}", &self.path);
-            println!("Output path: {path:?}");
-            println!("Input:\n{}\n", fs::read_to_string(&self.path).unwrap());
-            println!("Output:\n{result}\n");
-        }
-        if fs::write(&path, &result).is_err() {
-            fs::create_dir_all(path.parent().unwrap()).unwrap();
-            fs::write(path, &result).unwrap();
-        }
-    }
 }
 
 fn get_babel_error(error: &str) -> String {

tasks/transform_conformance/update_fixtures.js

@@ -13,8 +13,7 @@
 //    (or maybe don't - what does this option mean?)
 
 import { transformFileAsync } from '@babel/core';
-import assert from 'assert';
-import { copyFile, readdir, readFile, rename, writeFile } from 'fs/promises';
+import { readdir, readFile, rename, writeFile } from 'fs/promises';
 import { extname, join as pathJoin } from 'path';
 
 const PACKAGES = [
@@ -28,7 +27,10 @@ const FILTER_OUT_PLUGINS = [
   'transform-destructuring',
 ];
 
-const PACKAGES_PATH = pathJoin(import.meta.dirname, '../coverage/babel/packages');
+const PACKAGES_PATH = pathJoin(
+  import.meta.dirname,
+  '../coverage/babel/packages',
+);
 const OVERRIDES_PATH = pathJoin(import.meta.dirname, 'overrides');
 
 // Copied from `@babel/helper-transform-fixture-test-runner`
@@ -52,7 +54,12 @@ async function updateDir(dirPath, options, hasChangedOptions) {
   const dirFiles = [];
 
   const filenames = { options: null, input: null, output: null, exec: null };
-  const overrides = { options: false, input: false, output: false, exec: false };
+  const overrides = {
+    options: false,
+    input: false,
+    output: false,
+    exec: false,
+  };
 
   // Find files in dir
   for (const file of files) {
@@ -66,44 +73,6 @@ async function updateDir(dirPath, options, hasChangedOptions) {
     }
   }
 
-  // Find override files
-  const overridesDirPath = pathJoin(`${OVERRIDES_PATH}${dirPath.slice(PACKAGES_PATH.length)}`);
-  let overrideFiles;
-  try {
-    overrideFiles = await readdir(overridesDirPath, { withFileTypes: true });
-  } catch (err) {
-    if (err?.code !== 'ENOENT') throw err;
-  }
-
-  if (overrideFiles) {
-    for (const file of overrideFiles) {
-      if (file.isDirectory()) continue;
-
-      const filename = file.name;
-      // `reason.txt` files are to document why override is used
-      if (filename === 'reason.txt') continue;
-
-      const ext = extname(filename),
-        type = filename.slice(0, -ext.length),
-        path = pathJoin(overridesDirPath, filename);
-
-      assert(Object.hasOwn(overrides, type), `Unexpected override file: ${path}`);
-
-      const originalPath = pathJoin(dirPath, filename);
-      if (filenames[type]) {
-        const originalFilename = filenames[type];
-        assert(originalFilename === filename, `Unmatched override file: ${path} (original: ${originalFilename})`);
-        await backupFile(originalPath);
-      }
-
-      filenames[type] = filename;
-      overrides[type] = true;
-      if (type === 'options') hasChangedOptions = true;
-
-      await copyFile(path, originalPath);
-    }
-  }
-
   // Update options, save to file, and merge options with parent
   if (filenames.options) {
     const path = pathJoin(dirPath, filenames.options);
@@ -117,7 +86,11 @@ async function updateDir(dirPath, options, hasChangedOptions) {
   }
 
   // Run Babel with updated options/input
-  if (filenames.output && (hasChangedOptions || overrides.input) && !overrides.output) {
+  if (
+    filenames.output &&
+    (hasChangedOptions || overrides.input) &&
+    !overrides.output
+  ) {
     const inputPath = pathJoin(dirPath, filenames.input),
       outputPath = pathJoin(dirPath, filenames.output);
     await backupFile(outputPath);
@@ -165,7 +138,12 @@ function updateOptions(options) {
  * @returns {undefined}
  */
 async function transform(inputPath, outputPath, options) {
-  options = { ...options, configFile: false, babelrc: false, cwd: import.meta.dirname };
+  options = {
+    ...options,
+    configFile: false,
+    babelrc: false,
+    cwd: import.meta.dirname,
+  };
   delete options.SKIP_babel7plugins_babel8core;
   delete options.minNodeVersion;
 
@@ -179,9 +157,11 @@ async function transform(inputPath, outputPath, options) {
     return plugin;
   }
 
-  if (options.presets) options.presets = options.presets.map(preset => prefixName(preset, 'preset'));
+  if (options.presets) {
+    options.presets = options.presets.map((preset) => prefixName(preset, 'preset'));
+  }
 
-  options.plugins = (options.plugins || []).map(plugin => prefixName(plugin, 'plugin'));
+  options.plugins = (options.plugins || []).map((plugin) => prefixName(plugin, 'plugin'));
 
   let addExternalHelpersPlugin = true;
   if (Object.hasOwn(options, 'externalHelpers')) {
@@ -190,7 +170,10 @@ async function transform(inputPath, outputPath, options) {
   }
 
   if (addExternalHelpersPlugin) {
-    options.plugins.push(['@babel/plugin-external-helpers', { helperVersion: EXTERNAL_HELPERS_VERSION }]);
+    options.plugins.push([
+      '@babel/plugin-external-helpers',
+      { helperVersion: EXTERNAL_HELPERS_VERSION },
+    ]);
   }
 
   const { code } = await transformFileAsync(inputPath, options);