feat(transformer): add babel conformance test suite (#920)

.github/workflows/conformance.yml

@@ -49,6 +49,7 @@ jobs:
         uses: ./.github/actions/rustup
 
       - run: cargo coverage
+      - run: cargo run --release -p oxc_transform_conformance
 
       # - run: cargo minsize
 

Cargo.lock

@@ -1719,6 +1719,19 @@ dependencies = [
  "url",
 ]
 
+[[package]]
+name = "oxc_transform_conformance"
+version = "0.0.0"
+dependencies = [
+ "oxc_allocator",
+ "oxc_formatter",
+ "oxc_parser",
+ "oxc_span",
+ "oxc_tasks_common",
+ "oxc_transformer",
+ "walkdir",
+]
+
 [[package]]
 name = "oxc_transformer"
 version = "0.2.0"

crates/oxc_formatter/src/gen.rs

@@ -848,11 +848,11 @@ impl Gen for RegExpLiteral {
 
 impl Gen for StringLiteral {
     fn gen(&self, p: &mut Formatter) {
-        p.print(b'\'');
+        p.print_quote();
         for c in self.value.chars() {
             p.print_str(c.escape_default().to_string().as_bytes());
         }
-        p.print(b'\'');
+        p.print_quote();
     }
 }
 

crates/oxc_formatter/src/lib.rs

@@ -54,12 +54,14 @@ pub enum FinalEndOfLine {
 #[derive(Debug, Clone)]
 pub struct FormatterOptions {
     pub indentation: u8,
+    // <https://prettier.io/docs/en/options#quotes>
+    pub single_quote: bool,
     pub end_of_line: EndOfLine,
 }
 
 impl Default for FormatterOptions {
     fn default() -> Self {
-        Self { indentation: 4, end_of_line: EndOfLine::LF }
+        Self { indentation: 4, single_quote: false, end_of_line: EndOfLine::LF }
     }
 }
 
@@ -68,12 +70,14 @@ impl Default for FormatterOptions {
 pub struct InnerOptions {
     pub indentation: u8,
     pub end_of_line: FinalEndOfLine,
+    pub single_quote: bool,
 }
 
 impl From<FormatterOptions> for InnerOptions {
     fn from(options: FormatterOptions) -> Self {
         Self {
             indentation: options.indentation,
+            single_quote: options.single_quote,
             end_of_line: options.end_of_line.get_final_end_of_line(),
         }
     }
@@ -208,6 +212,11 @@ impl Formatter {
         self.print(b'=');
     }
 
+    #[inline]
+    pub fn print_quote(&mut self) {
+        self.print(if self.options.single_quote { b'\'' } else { b'"' });
+    }
+
     pub fn print_indent(&mut self) {
         for _ in 0..self.indentation {
             self.print(b' ');

crates/oxc_transformer/src/es2019/optional_catch_binding.rs

@@ -21,7 +21,7 @@ impl<'a> OptionalCatchBinding<'a> {
         if clause.param.is_some() {
             return;
         }
-        let binding_identifier = BindingIdentifier::new(Span::default(), "unused".into());
+        let binding_identifier = BindingIdentifier::new(Span::default(), "_unused".into());
         let binding_pattern_kind = self.ast.binding_identifier(binding_identifier);
         let binding_pattern = self.ast.binding_pattern(binding_pattern_kind, None, false);
         clause.param = Some(binding_pattern);

crates/oxc_transformer/src/lib.rs

@@ -19,12 +19,13 @@ use es2019::OptionalCatchBinding;
 
 #[derive(Debug, Default, Clone)]
 pub struct TransformOptions {
-    target: TransformTarget,
+    pub target: TransformTarget,
 }
 
 /// See <https://www.typescriptlang.org/tsconfig#target>
 #[derive(Debug, Default, Clone, Copy, Eq, PartialEq, Ord, PartialOrd)]
 pub enum TransformTarget {
+    ES2015,
     ES2016,
     ES2019,
     #[default]

justfile

@@ -56,9 +56,10 @@ test:
 lint:
   cargo lint -- --deny warnings
 
-# Run all the conformance tests. See `tasks/coverage`, `tasks/minsize`
+# Run all the conformance tests. See `tasks/coverage`, `tasks/transform_conformance`, `tasks/minsize`
 coverage:
   cargo coverage
+  cargo run --release -p oxc_transform_conformance
   # cargo minsize
 
 # Get code coverage

tasks/transform_conformance/Cargo.toml

@@ -0,0 +1,21 @@
+[package]
+name                  = "oxc_transform_conformance"
+version               = "0.0.0"
+publish               = false
+authors.workspace     = true
+description.workspace = true
+edition.workspace     = true
+homepage.workspace    = true
+keywords.workspace    = true
+license.workspace     = true
+repository.workspace  = true
+
+[dependencies]
+oxc_span   = { workspace = true }
+oxc_allocator   = { workspace = true }
+oxc_parser      = { workspace = true }
+oxc_formatter   = { workspace = true }
+oxc_transformer = { workspace = true }
+oxc_tasks_common = { workspace = true }
+
+walkdir      = { workspace = true }

tasks/transform_conformance/src/lib.rs

@@ -0,0 +1,46 @@
+use std::{fs, path::Path};
+use walkdir::WalkDir;
+
+use oxc_allocator::Allocator;
+use oxc_formatter::{Formatter, FormatterOptions};
+use oxc_parser::Parser;
+use oxc_span::SourceType;
+use oxc_tasks_common::project_root;
+use oxc_transformer::{TransformOptions, TransformTarget, Transformer};
+
+/// # Panics
+pub fn babel(name: &str) {
+    let root = project_root().join("tasks/coverage/babel/packages");
+    let root = root.join(name).join("test/fixtures");
+    let paths = WalkDir::new(root)
+        .into_iter()
+        .filter_map(Result::ok)
+        .filter(|e| e.file_name() == "input.js")
+        .map(|e| e.path().parent().unwrap().to_path_buf())
+        .collect::<Vec<_>>();
+    for path in paths {
+        babel_test(&path);
+    }
+}
+
+fn babel_test(path: &Path) {
+    let input_path = path.join("input.js");
+    let output_path = path.join("output.js");
+    let source_text = fs::read_to_string(&input_path).unwrap();
+    let expected = fs::read_to_string(output_path).unwrap();
+
+    let allocator = Allocator::default();
+    let source_type = SourceType::from_path(&input_path).unwrap();
+    let ret = Parser::new(&allocator, &source_text, source_type).parse();
+
+    let transform_options = TransformOptions { target: TransformTarget::ES2015 };
+    let program = allocator.alloc(ret.program);
+    Transformer::new(&allocator, &transform_options).build(program);
+
+    let formatter_options = FormatterOptions::default();
+    let printed = Formatter::new(source_text.len(), formatter_options).build(program);
+
+    let printed = printed.replace(|c: char| c.is_ascii_whitespace(), "");
+    let expected = expected.replace(|c: char| c.is_ascii_whitespace(), "");
+    assert_eq!(printed, expected, "{path:?}");
+}

tasks/transform_conformance/src/main.rs

@@ -0,0 +1,9 @@
+use oxc_transform_conformance::babel;
+
+fn main() {
+    let names = ["babel-plugin-transform-optional-catch-binding"];
+    for name in names {
+        babel(name);
+        println!("Passed: {name}");
+    }
+}