WIP: add impl

Author: chansuke

src/env_var.rs

@@ -1,10 +1,10 @@
+use crate::process;
 use std::collections::HashSet;
 use std::env;
 use std::ffi::OsStr;
 use std::path::PathBuf;
 use std::process::Command;
-
-use crate::process;
+use std::vec;
 
 pub const RUST_RECURSION_COUNT_MAX: u32 = 20;
 
@@ -13,14 +13,34 @@ trait ProcessEnvs {
     type Iter: Iterator<Item = Self::Item>;
 
     fn get_envs(&self) -> Self::Iter;
-    fn env<K, V>(&mut self, key: K, val: V) -> &mut Self
+    fn env<K, V>(&mut self, key: K, val: V)
     where
         K: AsRef<OsStr>,
         V: AsRef<OsStr>;
 }
 
+impl ProcessEnvs for Command {
+    type Item = Command;
+    type Iter = vec::IntoIter<Command>;
+
+    fn get_envs(&self) -> <Command as ProcessEnvs>::Iter {
+        self.get_envs()
+    }
+    fn env<K, V>(&mut self, key: K, val: V)
+    where
+        K: AsRef<OsStr>,
+        V: AsRef<OsStr>,
+    {
+        self.env(key, val);
+    }
+}
+
 #[allow(unused)]
-pub fn append_path(name: &str, value: Vec<PathBuf>, cmd: &mut Command) {
+pub fn append_path(
+    name: &str,
+    value: Vec<PathBuf>,
+    cmd: &mut dyn ProcessEnvs<Item = Command, Iter = vec::IntoIter<Command>>,
+) {
     let old_value = process().var_os(name);
     let mut parts: Vec<PathBuf>;
     if let Some(ref v) = old_value {
@@ -34,7 +54,11 @@ pub fn append_path(name: &str, value: Vec<PathBuf>, cmd: &mut Command) {
     }
 }
 
-pub fn prepend_path(name: &str, value: Vec<PathBuf>, cmd: &mut Command) {
+pub fn prepend_path(
+    name: &str,
+    value: Vec<PathBuf>,
+    cmd: &mut dyn ProcessEnvs<Item = Command, Iter = vec::IntoIter<Command>>,
+) {
     let old_value = process().var_os(name);
     let parts: Vec<PathBuf>;
     if let Some(ref v) = old_value {
@@ -97,9 +121,28 @@ mod tests {
     use crate::currentprocess;
     use crate::test::{with_saved_path, Env};
 
+    use super::ProcessEnvs;
     use std::collections::HashMap;
     use std::ffi::{OsStr, OsString};
 
+    struct TestCommand();
+
+    impl ProcessEnvs for TestCommand {
+        type Item = Command;
+        type Iter = vec::IntoIter<Command>;
+
+        fn get_envs(&self) -> <Command as ProcessEnvs>::Iter {
+            self.get_envs()
+        }
+        fn env<K, V>(&mut self, key: K, val: V) -> &mut <Command as ProcessEnvs>::Item
+        where
+            K: AsRef<OsStr>,
+            V: AsRef<OsStr>,
+        {
+            self.env(key, val)
+        }
+    }
+
     #[test]
     fn deduplicate_and_concat_paths() {
         let mut old_paths = vec![];
@@ -177,7 +220,6 @@ mod tests {
                 path_entries.push(path_z);
 
                 prepend_path("PATH", path_entries, &mut cmd);
-
                 let envs: Vec<(&OsStr, Option<&OsStr>)> = cmd.get_envs().collect();
 
                 assert_eq!(