Add `temp-env` as a dev dependency and refactor tests (#4)

## Summary

- Introduce `temp-env` crate (v0.3) to simplify environment variable
handling in tests.
- Replace custom `env::set_var`/`env::remove_var` calls with `temp_env`
utility methods.
- Eliminate unsafe code in test cases by leveraging `temp_env`'s scoped
modification functions.
- Update `Cargo.toml` and `Cargo.lock` to reflect the new development
dependency.

## Type of Change

<!-- Mark with an `x` all that apply -->

- [ ] 🐛 Bug fix (non-breaking change that fixes an issue)
- [ ] ✨ New feature (non-breaking change that adds functionality)
- [ ] 💥 Breaking change (fix or feature that would cause existing
functionality to not work as expected)
- [ ] 📚 Documentation update
- [x] 🧹 Code cleanup or refactoring
- [x] 🔧 Build system or dependency changes
- [x] 🧪 Test improvements

## What Changed?

This refactors tests to use temp-env instead of using unsafe code

## How Has This Been Tested?

<!-- Describe the tests you ran to verify your changes -->

- [x] Existing tests pass (`mise test`)
- [x] New tests added for new functionality
- [x] Manual testing performed
- [x] Code follows style guidelines (`mise lint`)

Cargo.lock

···
 version = 4
 
 [[package]]
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+version = "1.5.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "c08606f8c3cbf4ce6ec8e28fb0014a2c086708fe954eaa885384a6165172e7e8"
+
+[[package]]
+name = "bitflags"
+version = "2.9.3"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "34efbcccd345379ca2868b2b2c9d3782e9cc58ba87bc7d79d5b53d9c9ae6f25d"
+
+[[package]]
+name = "cfg-if"
+version = "1.0.3"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "2fd1289c04a9ea8cb22300a459a72a385d7c73d3259e2ed7dcb2af674838cfa9"
+
+[[package]]
 name = "dir_spec"
 version = "0.2.0"
+dependencies = [
+ "temp-env",
+]
+
+[[package]]
+name = "libc"
+version = "0.2.175"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "6a82ae493e598baaea5209805c49bbf2ea7de956d50d7da0da1164f9c6d28543"
+
+[[package]]
+name = "lock_api"
+version = "0.4.13"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "96936507f153605bddfcda068dd804796c84324ed2510809e5b2a624c81da765"
+dependencies = [
+ "autocfg",
+ "scopeguard",
+]
+
+[[package]]
+name = "parking_lot"
+version = "0.12.4"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "70d58bf43669b5795d1576d0641cfb6fbb2057bf629506267a92807158584a13"
+dependencies = [
+ "lock_api",
+ "parking_lot_core",
+]
+
+[[package]]
+name = "parking_lot_core"
+version = "0.9.11"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "bc838d2a56b5b1a6c25f55575dfc605fabb63bb2365f6c2353ef9159aa69e4a5"
+dependencies = [
+ "cfg-if",
+ "libc",
+ "redox_syscall",
+ "smallvec",
+ "windows-targets",
+]
+
+[[package]]
+name = "redox_syscall"
+version = "0.5.17"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "5407465600fb0548f1442edf71dd20683c6ed326200ace4b1ef0763521bb3b77"
+dependencies = [
+ "bitflags",
+]
+
+[[package]]
+name = "scopeguard"
+version = "1.2.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "94143f37725109f92c262ed2cf5e59bce7498c01bcc1502d7b9afe439a4e9f49"
+
+[[package]]
+name = "smallvec"
+version = "1.15.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "67b1b7a3b5fe4f1376887184045fcf45c69e92af734b7aaddc05fb777b6fbd03"
+
+[[package]]
+name = "temp-env"
+version = "0.3.6"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "96374855068f47402c3121c6eed88d29cb1de8f3ab27090e273e420bdabcf050"
+dependencies = [
+ "parking_lot",
+]
+
+[[package]]
+name = "windows-targets"
+version = "0.52.6"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "9b724f72796e036ab90c1021d4780d4d3d648aca59e491e6b98e725b84e99973"
+dependencies = [
+ "windows_aarch64_gnullvm",
+ "windows_aarch64_msvc",
+ "windows_i686_gnu",
+ "windows_i686_gnullvm",
+ "windows_i686_msvc",
+ "windows_x86_64_gnu",
+ "windows_x86_64_gnullvm",
+ "windows_x86_64_msvc",
+]
+
+[[package]]
+name = "windows_aarch64_gnullvm"
+version = "0.52.6"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "32a4622180e7a0ec044bb555404c800bc9fd9ec262ec147edd5989ccd0c02cd3"
+
+[[package]]
+name = "windows_aarch64_msvc"
+version = "0.52.6"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "09ec2a7bb152e2252b53fa7803150007879548bc709c039df7627cabbd05d469"
+
+[[package]]
+name = "windows_i686_gnu"
+version = "0.52.6"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "8e9b5ad5ab802e97eb8e295ac6720e509ee4c243f69d781394014ebfe8bbfa0b"
+
+[[package]]
+name = "windows_i686_gnullvm"
+version = "0.52.6"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "0eee52d38c090b3caa76c563b86c3a4bd71ef1a819287c19d586d7334ae8ed66"
+
+[[package]]
+name = "windows_i686_msvc"
+version = "0.52.6"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "240948bc05c5e7c6dabba28bf89d89ffce3e303022809e73deaefe4f6ec56c66"
+
+[[package]]
+name = "windows_x86_64_gnu"
+version = "0.52.6"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "147a5c80aabfbf0c7d901cb5895d1de30ef2907eb21fbbab29ca94c5b08b1a78"
+
+[[package]]
+name = "windows_x86_64_gnullvm"
+version = "0.52.6"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "24d5b23dc417412679681396f2b49f3de8c1473deb516bd34410872eff51ed0d"
+
+[[package]]
+name = "windows_x86_64_msvc"
+version = "0.52.6"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "589f6da84c646204747d1270a2a5661ea66ed1cced2631d546fdfb155959f9ec"

Cargo.toml

···
 keywords = ["xdg", "directories", "cross-platform", "filesystem", "config"]
 categories = ["filesystem", "os", "config"]
 
+[dev-dependencies]
+temp-env = "0.3"
+
 [lints.clippy]
 complexity = { level = "warn", priority = -1 }
 correctness = { level = "warn", priority = -1 }

src/lib.rs

···
 
 #[cfg(test)]
 mod tests {
-  use std::env;
-
   use super::*;
 
   #[test]
-  #[allow(unsafe_code)]
   fn test_resolve_xdg_path_absolute() {
-    unsafe {
-      env::set_var("TEST_XDG_VAR", "/absolute/path");
-    }
-    let result = Dir::resolve_xdg_path("TEST_XDG_VAR");
-    assert_eq!(result, Some(PathBuf::from("/absolute/path")));
-    unsafe {
-      env::remove_var("TEST_XDG_VAR");
-    }
+    temp_env::with_var("TEST_XDG_VAR", Some("/absolute/path"), || {
+      let result = Dir::resolve_xdg_path("TEST_XDG_VAR");
+      assert_eq!(result, Some(PathBuf::from("/absolute/path")));
+    });
   }
 
   #[test]
-  #[allow(unsafe_code)]
   fn test_resolve_xdg_path_relative_ignored() {
-    unsafe {
-      env::set_var("TEST_XDG_VAR", "relative/path");
-    }
-    let result = Dir::resolve_xdg_path("TEST_XDG_VAR");
-    assert_eq!(result, None);
-    unsafe {
-      env::remove_var("TEST_XDG_VAR");
-    }
+    temp_env::with_var("TEST_XDG_VAR", Some("relative/path"), || {
+      let result = Dir::resolve_xdg_path("TEST_XDG_VAR");
+      assert_eq!(result, None);
+    });
   }
 
   #[test]
-  #[allow(unsafe_code)]
   fn test_resolve_xdg_path_unset() {
-    unsafe {
-      env::remove_var("TEST_XDG_VAR");
-    }
-    let result = Dir::resolve_xdg_path("TEST_XDG_VAR");
-    assert_eq!(result, None);
+    temp_env::with_var_unset("TEST_XDG_VAR", || {
+      let result = Dir::resolve_xdg_path("TEST_XDG_VAR");
+      assert_eq!(result, None);
+    });
   }
 
   #[test]
···
   }
 
   #[test]
-  #[allow(unsafe_code)]
   fn test_config_home_default() {
-    unsafe {
-      env::remove_var("XDG_CONFIG_HOME");
-    }
-    let config = Dir::config_home();
-    if let Some(config_path) = config {
-      assert!(config_path.is_absolute());
+    temp_env::with_var_unset("XDG_CONFIG_HOME", || {
+      let config = Dir::config_home();
+      if let Some(config_path) = config {
+        assert!(config_path.is_absolute());
 
-      #[cfg(target_os = "linux")]
-      assert!(config_path.to_string_lossy().ends_with(".config"));
+        #[cfg(target_os = "linux")]
+        assert!(config_path.to_string_lossy().ends_with(".config"));
 
-      #[cfg(target_os = "macos")]
-      assert!(config_path.to_string_lossy().contains("Library/Application Support"));
-    }
+        #[cfg(target_os = "macos")]
+        assert!(config_path.to_string_lossy().contains("Library/Application Support"));
+      }
+    });
   }
 
   #[test]
-  #[allow(unsafe_code)]
   fn test_config_home_xdg_override() {
     let test_path = if cfg!(windows) { "C:\\test\\config" } else { "/test/config" };
-    unsafe {
-      env::set_var("XDG_CONFIG_HOME", test_path);
-    }
-    let config = Dir::config_home();
-    assert_eq!(config, Some(PathBuf::from(test_path)));
-    unsafe {
-      env::remove_var("XDG_CONFIG_HOME");
-    }
+    temp_env::with_var("XDG_CONFIG_HOME", Some(test_path), || {
+      let config = Dir::config_home();
+      assert_eq!(config, Some(PathBuf::from(test_path)));
+    });
   }
 
   #[test]
-  #[allow(unsafe_code)]
   fn test_cache_home_default() {
-    unsafe {
-      env::remove_var("XDG_CACHE_HOME");
-    }
-    let cache = Dir::cache_home();
-    if let Some(cache_path) = cache {
-      assert!(cache_path.is_absolute());
+    temp_env::with_var_unset("XDG_CACHE_HOME", || {
+      let cache = Dir::cache_home();
+      if let Some(cache_path) = cache {
+        assert!(cache_path.is_absolute());
 
-      #[cfg(target_os = "linux")]
-      assert!(cache_path.to_string_lossy().ends_with(".cache"));
+        #[cfg(target_os = "linux")]
+        assert!(cache_path.to_string_lossy().ends_with(".cache"));
 
-      #[cfg(target_os = "macos")]
-      assert!(cache_path.to_string_lossy().contains("Library/Caches"));
-    }
+        #[cfg(target_os = "macos")]
+        assert!(cache_path.to_string_lossy().contains("Library/Caches"));
+      }
+    });
   }
 
   #[test]
-  #[allow(unsafe_code)]
   fn test_data_home_default() {
-    unsafe {
-      env::remove_var("XDG_DATA_HOME");
-    }
-    let data = Dir::data_home();
-    if let Some(data_path) = data {
-      assert!(data_path.is_absolute());
+    temp_env::with_var_unset("XDG_DATA_HOME", || {
+      let data = Dir::data_home();
+      if let Some(data_path) = data {
+        assert!(data_path.is_absolute());
 
-      #[cfg(target_os = "linux")]
-      assert!(data_path.to_string_lossy().ends_with(".local/share"));
+        #[cfg(target_os = "linux")]
+        assert!(data_path.to_string_lossy().ends_with(".local/share"));
 
-      #[cfg(target_os = "macos")]
-      assert!(data_path.to_string_lossy().contains("Library/Application Support"));
-    }
+        #[cfg(target_os = "macos")]
+        assert!(data_path.to_string_lossy().contains("Library/Application Support"));
+      }
+    });
   }
 
   #[test]
-  #[allow(unsafe_code)]
   fn test_bin_home_default() {
-    unsafe {
-      env::remove_var("XDG_BIN_HOME");
-    }
-    let bin = Dir::bin_home();
-    if let Some(bin_path) = bin {
-      assert!(bin_path.is_absolute());
+    temp_env::with_var_unset("XDG_BIN_HOME", || {
+      let bin = Dir::bin_home();
+      if let Some(bin_path) = bin {
+        assert!(bin_path.is_absolute());
 
-      #[cfg(any(target_os = "linux", target_os = "macos"))]
-      assert!(bin_path.to_string_lossy().ends_with(".local/bin"));
+        #[cfg(any(target_os = "linux", target_os = "macos"))]
+        assert!(bin_path.to_string_lossy().ends_with(".local/bin"));
 
-      #[cfg(target_os = "windows")]
-      assert!(bin_path.to_string_lossy().contains("Programs"));
-    }
+        #[cfg(target_os = "windows")]
+        assert!(bin_path.to_string_lossy().contains("Programs"));
+      }
+    });
   }
 
   #[test]
-  #[allow(unsafe_code)]
   fn test_runtime_default() {
-    unsafe {
-      env::remove_var("XDG_RUNTIME_DIR");
-    }
-    let runtime = Dir::runtime();
-    if let Some(runtime_path) = runtime {
-      assert!(runtime_path.is_absolute());
+    temp_env::with_var_unset("XDG_RUNTIME_DIR", || {
+      let runtime = Dir::runtime();
+      if let Some(runtime_path) = runtime {
+        assert!(runtime_path.is_absolute());
 
-      #[cfg(any(target_os = "linux", target_os = "macos"))]
-      {
-        let path_str = runtime_path.to_string_lossy();
-        assert!(path_str.contains("tmp") || path_str.starts_with("/var/folders"));
+        #[cfg(any(target_os = "linux", target_os = "macos"))]
+        {
+          let path_str = runtime_path.to_string_lossy();
+          assert!(path_str.contains("tmp") || path_str.starts_with("/var/folders"));
+        }
       }
-    }
+    });
   }
 
   #[test]
-  #[allow(unsafe_code)]
   fn test_desktop_default() {
-    unsafe {
-      env::remove_var("XDG_DESKTOP_DIR");
-    }
-    let desktop = Dir::desktop();
-    if let Some(desktop_path) = desktop {
-      assert!(desktop_path.is_absolute());
-      assert!(desktop_path.to_string_lossy().ends_with("Desktop"));
-    }
+    temp_env::with_var_unset("XDG_DESKTOP_DIR", || {
+      let desktop = Dir::desktop();
+      if let Some(desktop_path) = desktop {
+        assert!(desktop_path.is_absolute());
+        assert!(desktop_path.to_string_lossy().ends_with("Desktop"));
+      }
+    });
   }
 
   #[test]
-  #[allow(unsafe_code)]
   fn test_videos_platform_differences() {
-    unsafe {
-      env::remove_var("XDG_VIDEOS_DIR");
-    }
-    let videos = Dir::videos();
-    if let Some(videos_path) = videos {
-      assert!(videos_path.is_absolute());
+    temp_env::with_var_unset("XDG_VIDEOS_DIR", || {
+      let videos = Dir::videos();
+      if let Some(videos_path) = videos {
+        assert!(videos_path.is_absolute());
 
-      #[cfg(target_os = "linux")]
-      assert!(videos_path.to_string_lossy().ends_with("Videos"));
+        #[cfg(target_os = "linux")]
+        assert!(videos_path.to_string_lossy().ends_with("Videos"));
 
-      #[cfg(target_os = "macos")]
-      assert!(videos_path.to_string_lossy().ends_with("Movies"));
+        #[cfg(target_os = "macos")]
+        assert!(videos_path.to_string_lossy().ends_with("Movies"));
 
-      #[cfg(target_os = "windows")]
-      assert!(videos_path.to_string_lossy().ends_with("Videos"));
-    }
+        #[cfg(target_os = "windows")]
+        assert!(videos_path.to_string_lossy().ends_with("Videos"));
+      }
+    });
   }
 
   #[test]
-  #[allow(unsafe_code)]
   fn test_publicshare_windows_absolute() {
-    unsafe {
-      env::remove_var("XDG_PUBLICSHARE_DIR");
-    }
-    let public = Dir::publicshare();
-    if let Some(public_path) = public {
-      assert!(public_path.is_absolute());
+    temp_env::with_var_unset("XDG_PUBLICSHARE_DIR", || {
+      let public = Dir::publicshare();
+      if let Some(public_path) = public {
+        assert!(public_path.is_absolute());
 
-      #[cfg(target_os = "windows")]
-      assert_eq!(public_path, PathBuf::from("C:\\Users\\Public"));
+        #[cfg(target_os = "windows")]
+        assert_eq!(public_path, PathBuf::from("C:\\Users\\Public"));
 
-      #[cfg(any(target_os = "linux", target_os = "macos"))]
-      assert!(public_path.to_string_lossy().ends_with("Public"));
-    }
+        #[cfg(any(target_os = "linux", target_os = "macos"))]
+        assert!(public_path.to_string_lossy().ends_with("Public"));
+      }
+    });
   }
 }