Implement brioche fmt --check argument

crates/brioche/src/brioche/script/format.rs

@@ -1,3 +1,5 @@
+use std::path::PathBuf;
+
 use crate::brioche::project::Project;
 
 #[tracing::instrument(skip(project), err)]
@@ -13,6 +15,23 @@ pub async fn format(project: &Project) -> anyhow::Result<()> {
     Ok(())
 }
 
+#[tracing::instrument(skip(project), err)]
+pub async fn check_format(project: &Project) -> anyhow::Result<Vec<PathBuf>> {
+    let mut unformatted = vec![];
+
+    for path in project.local_module_paths() {
+        let contents = tokio::fs::read_to_string(path).await?;
+
+        let formatted_contents = format_code(&contents)?;
+
+        if contents != formatted_contents {
+            unformatted.push(path.to_owned());
+        }
+    }
+
+    Ok(unformatted)
+}
+
 pub fn format_code(contents: &str) -> anyhow::Result<String> {
     let file_source =
         biome_js_syntax::JsFileSource::ts().with_module_kind(biome_js_syntax::ModuleKind::Module);

crates/brioche/src/main.rs

@@ -226,11 +226,32 @@ async fn format(args: FormatArgs) -> anyhow::Result<ExitCode> {
 
     let format_future = async {
         let project = brioche::brioche::project::resolve_project(&brioche, &args.project).await?;
-        brioche::brioche::script::format::format(&project).await?;
 
-        guard.shutdown_console().await;
+        if args.check {
+            let mut unformatted_files =
+                brioche::brioche::script::format::check_format(&project).await?;
+            unformatted_files.sort();
 
-        anyhow::Ok(ExitCode::SUCCESS)
+            guard.shutdown_console().await;
+
+            if unformatted_files.is_empty() {
+                println!("All files formatted");
+                Ok(ExitCode::SUCCESS)
+            } else {
+                println!("The following files are not formatted:");
+                for file in unformatted_files {
+                    println!("- {}", file.display());
+                }
+
+                Ok(ExitCode::FAILURE)
+            }
+        } else {
+            brioche::brioche::script::format::format(&project).await?;
+
+            guard.shutdown_console().await;
+
+            anyhow::Ok(ExitCode::SUCCESS)
+        }
     };
 
     let exit_code = format_future