Add a smoke test to ruff_fmt to debug formatter changes (#4)

Adds a smoke test to `ruff_fmt` to debug formatter changes.

This PR changes the return value of `fmt` to `Result<Formatted>` to allow printing the formatted IR in the quick test. The motivation behind returning `Formatted` is that the IR represents the formatted source code. Printing it only changes its representation from the IR to a string.

crates/ruff_fmt/src/lib.rs

@@ -1,5 +1,5 @@
 use anyhow::Result;
-use rome_formatter::{format, IndentStyle, Printed, SimpleFormatOptions};
+use rome_formatter::{format, Formatted, IndentStyle, SimpleFormatOptions};
 use rustpython_parser::lexer::LexResult;
 
 use crate::attachment::attach;
@@ -24,7 +24,7 @@ pub mod shared_traits;
 mod test;
 pub mod trivia;
 
-pub fn fmt(contents: &str) -> Result<Printed> {
+pub fn fmt(contents: &str) -> Result<Formatted<ASTFormatContext>> {
  // Tokenize once.
  let tokens: Vec<LexResult> = rustpython_helpers::tokenize(contents);
 
@@ -42,7 +42,7 @@ pub fn fmt(contents: &str) -> Result<Printed> {
  normalize_newlines(&mut python_cst);
  normalize_parentheses(&mut python_cst);
 
- let elements = format!(
+ format!(
  ASTFormatContext::new(
  SimpleFormatOptions {
  indent_style: IndentStyle::Space(4),
@@ -51,8 +51,8 @@ pub fn fmt(contents: &str) -> Result<Printed> {
  Locator::new(contents)
  ),
  [format::builders::block(&python_cst)]
- )?;
- elements.print().map_err(Into::into)
+ )
+ .map_err(Into::into)
 }
 
 #[cfg(test)]
@@ -73,8 +73,8 @@ mod tests {
  let content = std::fs::read_to_string(test_resource_path(
  Path::new("fixtures/black").join(path).as_path(),
  ))?;
- let printed = fmt(&content)?;
- insta::assert_display_snapshot!(snapshot, printed.as_code());
+ let formatted = fmt(&content)?;
+ insta::assert_display_snapshot!(snapshot, formatted.print()?.as_code());
  Ok(())
  }
 
@@ -90,8 +90,35 @@ mod tests {
  let content = std::fs::read_to_string(test_resource_path(
  Path::new("fixtures/black").join(path).as_path(),
  ))?;
- let printed = fmt(&content)?;
- insta::assert_display_snapshot!(snapshot, printed.as_code());
+ let formatted = fmt(&content)?;
+ insta::assert_display_snapshot!(snapshot, formatted.print()?.as_code());
  Ok(())
  }
+
+ /// Use this test to debug the formatting of some snipped
+ #[ignore]
+ #[test]
+ fn quick_test() {
+ let src = r#"
+{
+ k: v for k, v in a_very_long_variable_name_that_exceeds_the_line_length_by_far_keep_going
+}
+"#;
+ let formatted = fmt(&src).unwrap();
+
+ // Uncomment the `dbg` to print the IR.
+ // Use `dbg_write!(f, []) instead of `write!(f, [])` in your formatting code to print some IR
+ // inside of a `Format` implementation
+ // dbg!(formatted.document());
+
+ let printed = formatted.print().unwrap();
+
+ assert_eq!(
+ printed.as_code(),
+ r#"{
+ k: v
+ for k, v in a_very_long_variable_name_that_exceeds_the_line_length_by_far_keep_going
+}"#
+ );
+ }
 }

crates/ruff_fmt/src/main.rs

@@ -10,7 +10,7 @@ fn main() -> Result<()> {
  let contents = fs::read_to_string(cli.file)?;
  #[allow(clippy::print_stdout)]
  {
- println!("{}", fmt(&contents)?.as_code());
+ println!("{}", fmt(&contents)?.print()?.as_code());
  }
  Ok(())
 }