feat: Add path variable modification for the shells

crates/rattler_shell/src/activation.rs

@@ -12,6 +12,16 @@ use crate::shell::Shell;
 use indexmap::IndexMap;
 use rattler_conda_types::Platform;
 
+/// Type of modification done to the `PATH` variable
+pub enum PathModificationBehaviour {
+    /// Replaces the complete path variable with specified paths.
+    Replace,
+    /// Appends the new path variables to the path. E.g. '$PATH:/new/path'
+    Append,
+    /// Prepends the new path variables to the path. E.g. '/new/path:$PATH'
+    Prepend,
+}
+
 /// A struct that contains the values of the environment variables that are relevant for the activation process.
 /// The values are stored as strings. Currently, only the `PATH` and `CONDA_PREFIX` environment variables are used.
 pub struct ActivationVariables {
@@ -20,16 +30,18 @@ pub struct ActivationVariables {
 
     /// The value of the `PATH` environment variable that contains the paths to the executables
     pub path: Option<Vec<PathBuf>>,
+
+    /// The type of behaviour of what should happen with the defined paths.
+    pub path_modification_behaviour: PathModificationBehaviour,
 }
 
 impl ActivationVariables {
     /// Create a new `ActivationVariables` struct from the environment variables.
     pub fn from_env() -> Result<Self, std::env::VarError> {
         Ok(Self {
             conda_prefix: std::env::var("CONDA_PREFIX").ok().map(PathBuf::from),
-            path: std::env::var("PATH")
-                .ok()
-                .map(|p| std::env::split_paths(&p).collect::<Vec<_>>()),
+            path: None,
+            path_modification_behaviour: PathModificationBehaviour::Prepend,
         })
     }
 }
@@ -340,7 +352,11 @@ impl<T: Shell + Clone> Activator<T> {
         let path = [self.paths.clone(), path].concat();
 
         self.shell_type
-            .set_path(&mut script, path.as_slice())
+            .set_path(
+                &mut script,
+                path.as_slice(),
+                variables.path_modification_behaviour,
+            )
             .map_err(ActivationError::FailedToWriteActivationScript)?;
 
         // deliberately not taking care of `CONDA_SHLVL` or any other complications at this point
@@ -370,12 +386,15 @@ impl<T: Shell + Clone> Activator<T> {
 
 #[cfg(test)]
 mod tests {
-    use crate::shell;
+    use crate::{activation, shell};
     use std::str::FromStr;
 
     use super::*;
     use tempdir::TempDir;
 
+    #[cfg(unix)]
+    use activation::PathModificationBehaviour;
+
     #[test]
     fn test_collect_scripts() {
         let tdir = TempDir::new("test").unwrap();
@@ -487,7 +506,10 @@ mod tests {
     }
 
     #[cfg(unix)]
-    fn get_script<T: Shell>(shell_type: T) -> String
+    fn get_script<T: Shell>(
+        shell_type: T,
+        path_modification_behaviour: PathModificationBehaviour,
+    ) -> String
     where
         T: Clone,
     {
@@ -505,6 +527,7 @@ mod tests {
                     PathBuf::from("/sbin"),
                     PathBuf::from("/usr/local/bin"),
                 ]),
+                path_modification_behaviour,
             })
             .unwrap();
         let prefix = tdir.path().to_str().unwrap();
@@ -515,42 +538,53 @@ mod tests {
     #[test]
     #[cfg(unix)]
     fn test_activation_script_bash() {
-        let script = get_script(shell::Bash);
-        insta::assert_snapshot!(script);
+        let script = get_script(shell::Bash, PathModificationBehaviour::Append);
+        insta::assert_snapshot!("test_activation_script_bash_append", script);
+        let script = get_script(shell::Bash, PathModificationBehaviour::Replace);
+        insta::assert_snapshot!("test_activation_script_bash_replace", script);
+        let script = get_script(shell::Bash, PathModificationBehaviour::Prepend);
+        insta::assert_snapshot!("test_activation_script_bash_prepend", script);
     }
 
     #[test]
     #[cfg(unix)]
     fn test_activation_script_zsh() {
-        let script = get_script(shell::Zsh);
+        let script = get_script(shell::Zsh, PathModificationBehaviour::Append);
         insta::assert_snapshot!(script);
     }
 
     #[test]
     #[cfg(unix)]
     fn test_activation_script_fish() {
-        let script = get_script(shell::Fish);
+        let script = get_script(shell::Fish, PathModificationBehaviour::Append);
         insta::assert_snapshot!(script);
     }
 
     #[test]
     #[cfg(unix)]
     fn test_activation_script_powershell() {
-        let script = get_script(shell::PowerShell::default());
+        let script = get_script(
+            shell::PowerShell::default(),
+            PathModificationBehaviour::Append,
+        );
         insta::assert_snapshot!(script);
     }
 
     #[test]
     #[cfg(unix)]
     fn test_activation_script_cmd() {
-        let script = get_script(shell::CmdExe);
-        insta::assert_snapshot!(script);
+        let script = get_script(shell::CmdExe, PathModificationBehaviour::Append);
+        insta::assert_snapshot!("test_activation_script_cmd_append", script);
+        let script = get_script(shell::CmdExe, PathModificationBehaviour::Replace);
+        insta::assert_snapshot!("test_activation_script_cmd_replace", script);
+        let script = get_script(shell::CmdExe, PathModificationBehaviour::Prepend);
+        insta::assert_snapshot!("test_activation_script_cmd_prepend", script);
     }
 
     #[test]
     #[cfg(unix)]
     fn test_activation_script_xonsh() {
-        let script = get_script(shell::Xonsh);
+        let script = get_script(shell::Xonsh, PathModificationBehaviour::Append);
         insta::assert_snapshot!(script);
     }
 }

crates/rattler_shell/src/shell/mod.rs

@@ -1,5 +1,6 @@
 //! This module contains the [`Shell`] trait and implementations for various shells.
 
+use crate::activation::PathModificationBehaviour;
 use enum_dispatch::enum_dispatch;
 use itertools::Itertools;
 use std::process::Command;
@@ -46,9 +47,26 @@ pub trait Shell {
     }
 
     /// Set the PATH variable to the given paths.
-    fn set_path(&self, f: &mut impl Write, paths: &[PathBuf]) -> std::fmt::Result {
-        let path = std::env::join_paths(paths).unwrap();
-        self.set_env_var(f, "PATH", path.to_str().unwrap())
+    fn set_path(
+        &self,
+        f: &mut impl Write,
+        paths: &[PathBuf],
+        modification_behaviour: PathModificationBehaviour,
+    ) -> std::fmt::Result {
+        let mut paths_vec = paths
+            .iter()
+            .map(|path| path.to_string_lossy().into_owned())
+            .collect_vec();
+        // Replace, Append, or Prepend the path variable to the paths.
+        match modification_behaviour {
+            PathModificationBehaviour::Replace => (),
+            PathModificationBehaviour::Append => paths_vec.insert(0, self.format_env_var("PATH")),
+            PathModificationBehaviour::Prepend => paths_vec.push(self.format_env_var("PATH")),
+        }
+        // Create the shell specific list of paths.
+        let paths_string = paths_vec.join(self.path_seperator());
+
+        self.set_env_var(f, "PATH", paths_string.as_str())
     }
 
     /// The extension that shell scripts for this interpreter usually use.
@@ -59,6 +77,16 @@ pub trait Shell {
 
     /// Constructs a [`Command`] that will execute the specified script by this shell.
     fn create_run_script_command(&self, path: &Path) -> Command;
+
+    /// Path seperator
+    fn path_seperator(&self) -> &str {
+        ":"
+    }
+
+    /// Format the environment variable for the shell.
+    fn format_env_var(&self, var_name: &str) -> String {
+        format!("${{{var_name}}}")
+    }
 }
 
 /// Convert a native PATH on Windows to a Unix style path usign cygpath.
@@ -105,16 +133,35 @@ impl Shell for Bash {
         writeln!(f, ". \"{}\"", path.to_string_lossy())
     }
 
-    fn set_path(&self, f: &mut impl Write, paths: &[PathBuf]) -> std::fmt::Result {
-        let path = std::env::join_paths(paths).unwrap();
-
-        // check if we are on Windows, and if yes, convert native path to unix for (Git) Bash
-        if cfg!(windows) {
-            let path = native_path_to_unix(path.to_str().unwrap()).unwrap();
-            return self.set_env_var(f, "PATH", &path);
+    fn set_path(
+        &self,
+        f: &mut impl Write,
+        paths: &[PathBuf],
+        modification_behaviour: PathModificationBehaviour,
+    ) -> std::fmt::Result {
+        // Put paths in a vector of the correct format.
+        let mut paths_vec = paths
+            .iter()
+            .map(|path| {
+                // check if we are on Windows, and if yes, convert native path to unix for (Git) Bash
+                if cfg!(windows) {
+                    native_path_to_unix(path.to_string_lossy().as_ref()).unwrap()
+                } else {
+                    path.to_string_lossy().into_owned()
+                }
+            })
+            .collect_vec();
+
+        // Replace, Append, or Prepend the path variable to the paths.
+        match modification_behaviour {
+            PathModificationBehaviour::Replace => (),
+            PathModificationBehaviour::Prepend => paths_vec.push(self.format_env_var("PATH")),
+            PathModificationBehaviour::Append => paths_vec.insert(0, self.format_env_var("PATH")),
         }
+        // Create the shell specific list of paths.
+        let paths_string = paths_vec.join(self.path_seperator());
 
-        self.set_env_var(f, "PATH", path.to_str().unwrap())
+        self.set_env_var(f, "PATH", paths_string.as_str())
     }
 
     fn extension(&self) -> &str {
@@ -241,6 +288,14 @@ impl Shell for CmdExe {
         cmd.arg("/D").arg("/C").arg(path);
         cmd
     }
+
+    fn path_seperator(&self) -> &str {
+        ";"
+    }
+
+    fn format_env_var(&self, var_name: &str) -> String {
+        format!("%{var_name}%")
+    }
 }
 
 /// A [`Shell`] implementation for PowerShell.
@@ -275,6 +330,14 @@ impl Shell for PowerShell {
         cmd.arg(path);
         cmd
     }
+
+    fn path_seperator(&self) -> &str {
+        ";"
+    }
+
+    fn format_env_var(&self, var_name: &str) -> String {
+        format!("$Env:{var_name}")
+    }
 }
 
 /// A [`Shell`] implementation for the Fish shell.
@@ -453,7 +516,9 @@ impl<T: Shell> ShellScript<T> {
 
     /// Set the PATH environment variable to the given paths.
     pub fn set_path(&mut self, paths: &[PathBuf]) -> &mut Self {
-        self.shell.set_path(&mut self.contents, paths).unwrap();
+        self.shell
+            .set_path(&mut self.contents, paths, PathModificationBehaviour::Append)
+            .unwrap();
         self
     }
 

crates/rattler_shell/src/snapshots/rattler_shell__activation__tests__activation_script_bash.snap

@@ -2,7 +2,7 @@
 source: crates/rattler_shell/src/activation.rs
 expression: script
 ---
-export PATH="__PREFIX__/bin:/usr/bin:/bin:/usr/sbin:/sbin:/usr/local/bin"
+export PATH="__PREFIX__/bin:/usr/bin:/bin:/usr/sbin:/sbin:/usr/local/bin:${PATH}"
 export CONDA_PREFIX="__PREFIX__"
 . "__PREFIX__/etc/conda/activate.d/script1.sh"
 

crates/rattler_shell/src/snapshots/rattler_shell__activation__tests__activation_script_cmd.snap

@@ -2,6 +2,6 @@
 source: crates/rattler_shell/src/activation.rs
 expression: script
 ---
-@SET "PATH=__PREFIX__/bin:/usr/bin:/bin:/usr/sbin:/sbin:/usr/local/bin"
+@SET "PATH=%PATH%;__PREFIX__/bin;/usr/bin;/bin;/usr/sbin;/sbin;/usr/local/bin"
 @SET "CONDA_PREFIX=__PREFIX__"
 

crates/rattler_shell/src/snapshots/rattler_shell__activation__tests__activation_script_fish.snap

@@ -2,6 +2,6 @@
 source: crates/rattler_shell/src/activation.rs
 expression: script
 ---
-set -gx PATH "__PREFIX__/bin:/usr/bin:/bin:/usr/sbin:/sbin:/usr/local/bin"
+set -gx PATH "${PATH}:__PREFIX__/bin:/usr/bin:/bin:/usr/sbin:/sbin:/usr/local/bin"
 set -gx CONDA_PREFIX "__PREFIX__"
 

crates/rattler_shell/src/snapshots/rattler_shell__activation__tests__activation_script_powershell.snap

@@ -2,6 +2,6 @@
 source: crates/rattler_shell/src/activation.rs
 expression: script
 ---
-$Env:PATH = "__PREFIX__/bin:/usr/bin:/bin:/usr/sbin:/sbin:/usr/local/bin"
+$Env:PATH = "$Env:PATH;__PREFIX__/bin;/usr/bin;/bin;/usr/sbin;/sbin;/usr/local/bin"
 $Env:CONDA_PREFIX = "__PREFIX__"
 

crates/rattler_shell/src/snapshots/rattler_shell__activation__tests__activation_script_xonsh.snap

@@ -2,7 +2,7 @@
 source: crates/rattler_shell/src/activation.rs
 expression: script
 ---
-$PATH = "__PREFIX__/bin:/usr/bin:/bin:/usr/sbin:/sbin:/usr/local/bin"
+$PATH = "${PATH}:__PREFIX__/bin:/usr/bin:/bin:/usr/sbin:/sbin:/usr/local/bin"
 $CONDA_PREFIX = "__PREFIX__"
 source-bash "__PREFIX__/etc/conda/activate.d/script1.sh"
 

crates/rattler_shell/src/snapshots/rattler_shell__activation__tests__activation_script_zsh.snap

@@ -2,7 +2,7 @@
 source: crates/rattler_shell/src/activation.rs
 expression: script
 ---
-export PATH="__PREFIX__/bin:/usr/bin:/bin:/usr/sbin:/sbin:/usr/local/bin"
+export PATH="${PATH}:__PREFIX__/bin:/usr/bin:/bin:/usr/sbin:/sbin:/usr/local/bin"
 export CONDA_PREFIX="__PREFIX__"
 . "__PREFIX__/etc/conda/activate.d/script1.sh"
 

crates/rattler_shell/src/snapshots/rattler_shell__activation__tests__test_activation_script_bash_append.snap

@@ -0,0 +1,8 @@
+---
+source: crates/rattler_shell/src/activation.rs
+expression: script
+---
+export PATH="${PATH}:__PREFIX__/bin:/usr/bin:/bin:/usr/sbin:/sbin:/usr/local/bin"
+export CONDA_PREFIX="__PREFIX__"
+. "__PREFIX__/etc/conda/activate.d/script1.sh"
+

crates/rattler_shell/src/snapshots/rattler_shell__activation__tests__test_activation_script_bash_prepend.snap

@@ -0,0 +1,8 @@
+---
+source: crates/rattler_shell/src/activation.rs
+expression: script
+---
+export PATH="__PREFIX__/bin:/usr/bin:/bin:/usr/sbin:/sbin:/usr/local/bin:${PATH}"
+export CONDA_PREFIX="__PREFIX__"
+. "__PREFIX__/etc/conda/activate.d/script1.sh"
+

crates/rattler_shell/src/snapshots/rattler_shell__activation__tests__test_activation_script_bash_replace.snap

@@ -0,0 +1,8 @@
+---
+source: crates/rattler_shell/src/activation.rs
+expression: script
+---
+export PATH="__PREFIX__/bin:/usr/bin:/bin:/usr/sbin:/sbin:/usr/local/bin"
+export CONDA_PREFIX="__PREFIX__"
+. "__PREFIX__/etc/conda/activate.d/script1.sh"
+

crates/rattler_shell/src/snapshots/rattler_shell__activation__tests__test_activation_script_cmd_append.snap

@@ -0,0 +1,7 @@
+---
+source: crates/rattler_shell/src/activation.rs
+expression: script
+---
+@SET "PATH=%PATH%;__PREFIX__/bin;/usr/bin;/bin;/usr/sbin;/sbin;/usr/local/bin"
+@SET "CONDA_PREFIX=__PREFIX__"
+

crates/rattler_shell/src/snapshots/rattler_shell__activation__tests__test_activation_script_cmd_prepend.snap

@@ -0,0 +1,7 @@
+---
+source: crates/rattler_shell/src/activation.rs
+expression: script
+---
+@SET "PATH=__PREFIX__/bin;/usr/bin;/bin;/usr/sbin;/sbin;/usr/local/bin;%PATH%"
+@SET "CONDA_PREFIX=__PREFIX__"
+

crates/rattler_shell/src/snapshots/rattler_shell__activation__tests__test_activation_script_cmd_replace.snap

@@ -0,0 +1,7 @@
+---
+source: crates/rattler_shell/src/activation.rs
+expression: script
+---
+@SET "PATH=__PREFIX__/bin;/usr/bin;/bin;/usr/sbin;/sbin;/usr/local/bin"
+@SET "CONDA_PREFIX=__PREFIX__"
+