feature[env]: Add support for --chdir=DIR in env (fixes #1568) (#1569)

src/uu/env/src/env.rs

@@ -28,6 +28,7 @@ A mere - implies -i. If no COMMAND, print the resulting environment.
 struct Options<'a> {
     ignore_env: bool,
     null: bool,
+    running_directory: Option<&'a str>,
     files: Vec<&'a str>,
     unsets: Vec<&'a str>,
     sets: Vec<(&'a str, &'a str)>,
@@ -128,6 +129,13 @@ fn create_app() -> App<'static, 'static> {
             .short("i")
             .long("ignore-environment")
             .help("start with an empty environment"))
+        .arg(Arg::with_name("chdir")
+            .short("c")
+            .long("chdir")
+            .takes_value(true)
+            .number_of_values(1)
+            .value_name("DIR")
+            .help("change working directory to DIR"))
         .arg(Arg::with_name("null")
             .short("0")
             .long("null")
@@ -158,6 +166,7 @@ fn run_env(args: impl uucore::Args) -> Result<(), i32> {
 
     let ignore_env = matches.is_present("ignore-environment");
     let null = matches.is_present("null");
+    let running_directory = matches.value_of("chdir");
     let files = matches
         .values_of("file")
         .map(Iterator::collect)
@@ -170,12 +179,24 @@ fn run_env(args: impl uucore::Args) -> Result<(), i32> {
     let mut opts = Options {
         ignore_env,
         null,
+        running_directory,
         files,
         unsets,
         sets: vec![],
         program: vec![],
     };
 
+    // change directory
+    if let Some(d) = opts.running_directory {
+        match env::set_current_dir(d) {
+            Ok(()) => d,
+            Err(error) => {
+                eprintln!("env: cannot change directory to \"{}\": {}", d, error);
+                return Err(125);
+            }
+        };
+    }
+
     // we handle the name, value pairs and the program to be executed by treating them as external
     // subcommands in clap
     if let (external, Some(matches)) = matches.subcommand() {

tests/by-util/test_env.rs

@@ -1,4 +1,11 @@
+#[cfg(not(windows))]
+use std::fs;
+
+use std::path::Path;
+extern crate tempfile;
+use self::tempfile::tempdir;
 use crate::common::util::*;
+use std::env;
 
 #[test]
 fn test_env_help() {
@@ -150,3 +157,64 @@ fn test_fail_null_with_program() {
     let out = new_ucmd!().arg("--null").arg("cd").fails().stderr;
     assert!(out.contains("cannot specify --null (-0) with command"));
 }
+
+#[cfg(not(windows))]
+#[test]
+fn test_change_directory() {
+    let scene = TestScenario::new(util_name!());
+    let temporary_directory = tempdir().unwrap();
+    let temporary_path = fs::canonicalize(temporary_directory.path()).unwrap();
+    assert_ne!(env::current_dir().unwrap(), temporary_path);
+
+    // command to print out current working directory
+    let pwd = "pwd";
+
+    let out = scene
+        .ucmd()
+        .arg("--chdir")
+        .arg(&temporary_path)
+        .arg(pwd)
+        .run()
+        .stdout;
+    assert_eq!(out.trim(), temporary_path.as_os_str())
+}
+
+// no way to consistently get "current working directory", `cd` doesn't work @ CI
+// instead, we test that the unique temporary directory appears somewhere in the printed variables
+#[cfg(windows)]
+#[test]
+fn test_change_directory() {
+    let scene = TestScenario::new(util_name!());
+    let temporary_directory = tempdir().unwrap();
+    let temporary_path = temporary_directory.path();
+
+    assert_ne!(env::current_dir().unwrap(), temporary_path);
+
+    let out = scene
+        .ucmd()
+        .arg("--chdir")
+        .arg(&temporary_path)
+        .run()
+        .stdout;
+    assert_eq!(
+        out.lines()
+            .any(|line| line.ends_with(temporary_path.file_name().unwrap().to_str().unwrap())),
+        false
+    );
+}
+
+#[test]
+fn test_fail_change_directory() {
+    let scene = TestScenario::new(util_name!());
+    let some_non_existing_path = "some_nonexistent_path";
+    assert_eq!(Path::new(some_non_existing_path).is_dir(), false);
+
+    let out = scene
+        .ucmd()
+        .arg("--chdir")
+        .arg(some_non_existing_path)
+        .arg("pwd")
+        .fails()
+        .stderr;
+    assert!(out.contains("env: cannot change directory to "));
+}