check_diff function rewrite

check_diff/Cargo.toml

@@ -11,3 +11,4 @@ tracing = "0.1.37"
 tracing-subscriber = { version = "0.3.17", features = ["env-filter"] }
 tempfile = "3"
 walkdir = "2.5.0"
+diffy = "0.4.0"

check_diff/src/lib.rs

@@ -1,5 +1,6 @@
+use diffy;
 use std::env;
-use std::fs::OpenOptions;
+use std::fmt::Debug;
 use std::io;
 use std::path::{Path, PathBuf};
 use std::process::Command;
@@ -26,6 +27,12 @@ pub enum CheckDiffError {
     IO(std::io::Error),
 }
 
+impl Debug for CheckDiffError {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        f.debug_struct("CheckDiffError").finish()
+    }
+}
+
 impl From<io::Error> for CheckDiffError {
     fn from(error: io::Error) -> Self {
         CheckDiffError::IO(error)
@@ -59,7 +66,6 @@ impl From<io::Error> for GitError {
 }
 
 // will be used in future PRs, just added to make the compiler happy
-#[allow(dead_code)]
 pub struct CheckDiffRunners {
     pub feature_runner: RustfmtRunner,
     pub src_runner: RustfmtRunner,
@@ -70,6 +76,21 @@ pub struct RustfmtRunner {
     binary_path: PathBuf,
 }
 
+impl CheckDiffRunners {
+    /// Creates a diff generated by running the source and feature binaries on the same file path
+    pub fn create_diff(
+        &self,
+        path: &Path,
+        additional_configs: &Option<Vec<String>>,
+    ) -> Result<String, CheckDiffError> {
+        let code = std::fs::read_to_string(path)?;
+        let src_format = self.src_runner.format_code(&code, additional_configs)?;
+        let feature_format = self.feature_runner.format_code(&code, additional_configs)?;
+        let diff = diffy::create_patch(src_format.as_str(), feature_format.as_str());
+        Ok(format!("{diff}"))
+    }
+}
+
 impl RustfmtRunner {
     fn get_binary_version(&self) -> Result<String, CheckDiffError> {
         let Ok(command) = Command::new(&self.binary_path)
@@ -86,19 +107,18 @@ impl RustfmtRunner {
         return Ok(binary_version.to_string());
     }
 
-    //  Run rusfmt with the --check flag to see if a diff is produced.
+    //  Run rusfmt with the --check flag to see if a diff is produced. Runs on the code specified
     //
     // Parameters:
     // binary_path: Path to a rustfmt binary
-    // output_path: Output file path for the diff
+    // code: Code to run the binary on
     // config: Any additional configuration options to pass to rustfmt
     //
-    #[allow(dead_code)]
-    fn create_diff(
+    fn format_code<'a>(
         &self,
-        output_path: &Path,
-        config: Option<Vec<String>>,
-    ) -> Result<(), CheckDiffError> {
+        code: &'a str,
+        config: &Option<Vec<String>>,
+    ) -> Result<String, CheckDiffError> {
         let config_arg: String = match config {
             Some(configs) => {
                 let mut result = String::new();
@@ -117,33 +137,18 @@ impl RustfmtRunner {
             config_arg.as_str()
         );
 
-        // walks the "." directory and finds all files with .rs extensions
-        for entry in WalkDir::new(".").into_iter().filter_map(|e| e.ok()) {
-            let path = entry.path();
-            if path.is_file() && path.extension().map_or(false, |ext| ext == "rs") {
-                let file = OpenOptions::new()
-                    .write(true)
-                    .append(true)
-                    .open(output_path)?;
-                let Ok(_) = Command::new(&self.binary_path)
-                    .env("LD_LIBRARY_PATH", &self.ld_library_path)
-                    .args([
-                        "--unstable-features",
-                        "--skip-children",
-                        "--check",
-                        "--color=always",
-                        config.as_str(),
-                    ])
-                    .stdout(file)
-                    .output()
-                else {
-                    return Err(CheckDiffError::FailedWritingToFile(
-                        "Failed to write to file",
-                    ));
-                };
-            }
-        }
-        Ok(())
+        let output = Command::new(&self.binary_path)
+            .env("LD_LIBRARY_PATH", &self.ld_library_path)
+            .args([
+                "--unstable-features",
+                "--skip-children",
+                "--emit=stdout",
+                config.as_str(),
+                code,
+            ])
+            .output()?;
+
+        Ok(std::str::from_utf8(&output.stdout)?.to_string())
     }
 }
 
@@ -335,3 +340,25 @@ pub fn compile_rustfmt(
         feature_runner,
     });
 }
+
+pub fn check_diff(config: Option<Vec<String>>, runners: CheckDiffRunners) -> i32 {
+    let mut errors = 0;
+    for entry in WalkDir::new(".").into_iter().filter_map(|e| e.ok()) {
+        let path = entry.path();
+        if path.is_file() && path.extension().map_or(false, |ext| ext == "rs") {
+            match runners.create_diff(path, &config) {
+                Ok(diff) => {
+                    if !diff.is_empty() {
+                        eprint!("diff");
+                        errors += 1;
+                    }
+                }
+                Err(e) => {
+                    eprintln!("Error creating diff for {:?}: {:?}", path.display(), e);
+                    errors += 1;
+                }
+            }
+        }
+    }
+    return errors;
+}

check_diff/src/main.rs

@@ -1,4 +1,4 @@
-use check_diff::compile_rustfmt;
+use check_diff::{check_diff, compile_rustfmt, CheckDiffError};
 use clap::Parser;
 use tempfile::Builder;
 use tracing::info;
@@ -19,17 +19,21 @@ struct CliInputs {
     rustfmt_config: Option<Vec<String>>,
 }
 
-fn main() {
+fn main() -> Result<(), CheckDiffError> {
     tracing_subscriber::fmt()
         .with_env_filter(tracing_subscriber::EnvFilter::from_env("CHECK_DIFF_LOG"))
         .init();
     let args = CliInputs::parse();
     let tmp_dir = Builder::new().tempdir_in("").unwrap();
     info!("Created tmp_dir {:?}", tmp_dir);
-    let _ = compile_rustfmt(
+    let check_diff_runners = compile_rustfmt(
         tmp_dir.path(),
         args.remote_repo_url,
         args.feature_branch,
         args.commit_hash,
-    );
+    )?;
+
+    let _ = check_diff(args.rustfmt_config, check_diff_runners);
+
+    Ok(())
 }