refactor: Improve test isolation and dependency injection

- Replace per-request service creation with dependency injection
- Add .env support for UPLOAD_DIR configuration
- Implement sequential test execution to prevent race conditions
- Auto-generate test problem IDs using rand

Author: reddevilmidzy

.env

@@ -1 +1,2 @@
 DATABASE_URL="postgres://postgres:password@localhost:5432/coduck"
+UPLOAD_DIR="uploads"

Cargo.toml

@@ -14,13 +14,16 @@ name = "coduck-backend"
 anyhow = "1.0"
 axum = { version = "0.8.4", features = ["json", "multipart"] }
 chrono = { version = "0.4.38", features = ["serde"] }
+dotenv = "0.15.0"
 git2 = "0.20.2"
 serde = { version = "1.0.219", features = ["derive"] }
 serde_json = "1.0.133"
 tokio = { version = "1.45.1", features = ["full"] }
 uuid = { version = "1.17.0", features = ["v4"] }
 
 [dev-dependencies]
+rand = "0.9"
 reqwest = { version = "0.12.19", features = ["json", "rustls-tls"] }
 rstest = "0.25.0"
+serial_test = "3.2"
 tempfile = "3.20"

src/file_manager/git.rs

@@ -5,36 +5,24 @@ use git2::{DiffOptions, IndexAddOption, Repository, StatusOptions, Time};
 use std::path::PathBuf;
 use tokio::fs;
 
-const UPLOAD_DIR: &str = "uploads";
 const DEFAULT_DIRECTORIES: [&str; 3] = ["solutions", "tests", "statements"];
 
 #[derive(Debug)]
 struct GitManager {
     problem_id: u32,
-    base_path: Option<PathBuf>,
+    base_path: PathBuf,
 }
 
 impl GitManager {
-    fn new(problem_id: u32) -> Self {
+    fn new(problem_id: u32, base_path: PathBuf) -> Self {
         Self {
             problem_id,
-            base_path: None,
-        }
-    }
-
-    fn new_with_path(problem_id: u32, base_path: PathBuf) -> Self {
-        Self {
-            problem_id,
-            base_path: Some(base_path),
+            base_path,
         }
     }
 
     fn get_upload_path(&self) -> PathBuf {
-        if let Some(ref base_path) = self.base_path {
-            base_path.join(self.problem_id.to_string())
-        } else {
-            PathBuf::from(UPLOAD_DIR).join(self.problem_id.to_string())
-        }
+        self.base_path.join(self.problem_id.to_string())
     }
 
     fn git_init(&self) -> Result<()> {
@@ -211,6 +199,7 @@ struct FileInfo {
 #[cfg(test)]
 mod tests {
     use super::*;
+    use rand::Rng;
     use rstest::rstest;
     use std::path::Path;
     use tempfile::TempDir;
@@ -244,8 +233,8 @@ mod tests {
     #[tokio::test]
     async fn can_init_git_repository() -> Result<(), std::io::Error> {
         let temp_dir = TempDir::new()?;
-        let problem_id = 10;
-        let git_manager = GitManager::new_with_path(problem_id, temp_dir.path().to_path_buf());
+        let problem_id = rand::rng().random_range(0..=u32::MAX);
+        let git_manager = GitManager::new(problem_id, temp_dir.path().to_path_buf());
         assert!(git_manager.git_init().is_ok());
         assert!(Path::new(git_manager.get_upload_path().to_str().unwrap()).exists());
         assert!(Path::new(
@@ -259,8 +248,8 @@ mod tests {
     #[tokio::test]
     async fn can_set_config() -> Result<(), std::io::Error> {
         let temp_dir = TempDir::new()?;
-        let problem_id = 11;
-        let git_manager = GitManager::new_with_path(problem_id, temp_dir.path().to_path_buf());
+        let problem_id = rand::rng().random_range(0..=u32::MAX);
+        let git_manager = GitManager::new(problem_id, temp_dir.path().to_path_buf());
         assert!(git_manager.git_init().is_ok());
         let repo = git_manager.get_repository().unwrap();
         let config = repo.config().unwrap();
@@ -276,8 +265,8 @@ mod tests {
     #[tokio::test]
     async fn can_create_default_file() -> Result<(), std::io::Error> {
         let temp_dir = TempDir::new()?;
-        let problem_id = 12;
-        let git_manager = GitManager::new_with_path(problem_id, temp_dir.path().to_path_buf());
+        let problem_id = rand::rng().random_range(0..=u32::MAX);
+        let git_manager = GitManager::new(problem_id, temp_dir.path().to_path_buf());
         assert!(git_manager.create_default_directories().await.is_ok());
         assert!(Path::new(
             format!(
@@ -306,8 +295,8 @@ mod tests {
     #[tokio::test]
     async fn can_create_problem() -> Result<(), std::io::Error> {
         let temp_dir = TempDir::new()?;
-        let problem_id = 13;
-        let git_manager = GitManager::new_with_path(problem_id, temp_dir.path().to_path_buf());
+        let problem_id = rand::rng().random_range(0..=u32::MAX);
+        let git_manager = GitManager::new(problem_id, temp_dir.path().to_path_buf());
         assert!(git_manager.create_problem().await.is_ok());
         assert!(Path::new(git_manager.get_upload_path().to_str().unwrap()).exists());
         assert!(Path::new(
@@ -341,8 +330,8 @@ mod tests {
     #[tokio::test]
     async fn can_get_git_status() -> Result<(), tokio::io::Error> {
         let temp_dir = TempDir::new()?;
-        let problem_id = 14;
-        let git_manager = GitManager::new_with_path(problem_id, temp_dir.path().to_path_buf());
+        let problem_id = rand::rng().random_range(0..=u32::MAX);
+        let git_manager = GitManager::new(problem_id, temp_dir.path().to_path_buf());
 
         git_manager.git_init().unwrap();
 
@@ -387,8 +376,8 @@ mod tests {
     #[tokio::test]
     async fn can_git_add() -> Result<(), tokio::io::Error> {
         let temp_dir = TempDir::new()?;
-        let problem_id = 15;
-        let git_manager = GitManager::new_with_path(problem_id, temp_dir.path().to_path_buf());
+        let problem_id = rand::rng().random_range(0..=u32::MAX);
+        let git_manager = GitManager::new(problem_id, temp_dir.path().to_path_buf());
 
         git_manager.git_init().unwrap();
 
@@ -433,8 +422,8 @@ mod tests {
     #[tokio::test]
     async fn can_commit() -> Result<(), tokio::io::Error> {
         let temp_dir = TempDir::new()?;
-        let problem_id = 16;
-        let git_manager = GitManager::new_with_path(problem_id, temp_dir.path().to_path_buf());
+        let problem_id = rand::rng().random_range(0..=u32::MAX);
+        let git_manager = GitManager::new(problem_id, temp_dir.path().to_path_buf());
         git_manager.git_init().unwrap();
 
         fs::create_dir_all(format!(
@@ -475,8 +464,8 @@ mod tests {
     #[tokio::test]
     async fn can_get_log() -> Result<(), tokio::io::Error> {
         let temp_dir = TempDir::new()?;
-        let problem_id = 17;
-        let git_manager = GitManager::new_with_path(problem_id, temp_dir.path().to_path_buf());
+        let problem_id = rand::rng().random_range(0..=u32::MAX);
+        let git_manager = GitManager::new(problem_id, temp_dir.path().to_path_buf());
         git_manager.git_init().unwrap();
         git_manager.create_default_directories().await.unwrap();