Fix conda environment discovery for child environments under envs folder

crates/pet-conda/src/environment_locations.rs

@@ -197,6 +197,23 @@ pub fn get_environments(conda_dir: &Path) -> Vec<PathBuf> {
         }
     } else if is_conda_env(conda_dir) {
         envs.push(conda_dir.to_path_buf());
+        // If this is a conda environment under an `envs` folder, check if the grandparent
+        // is the conda install directory (base env) and include it as well.
+        // E.g. if conda_dir is `/opt/homebrew/Caskroom/miniforge/base/envs/test`,
+        // then the grandparent `/opt/homebrew/Caskroom/miniforge/base` is the base env.
+        // This ensures the base conda environment is discovered when only child envs are
+        // listed in environments.txt (see https://github.com/microsoft/python-environment-tools/issues/236)
+        if let Some(parent) = conda_dir.parent() {
+            if parent.file_name().map(|n| n == "envs").unwrap_or(false) {
+                if let Some(grandparent) = parent.parent() {
+                    if is_conda_install(grandparent) && !envs.contains(&grandparent.to_path_buf()) {
+                        // Recursively get environments from the conda install directory
+                        // This will add the base env and any other sibling envs
+                        envs.append(&mut get_environments(grandparent));
+                    }
+                }
+            }
+        }
     } else if conda_dir.join("envs").exists() {
         // This could be a directory where conda environments are stored.
         // I.e. its not necessarily the root conda install directory.

crates/pet-conda/tests/environment_locations_test.rs

@@ -39,3 +39,59 @@ fn list_conda_envs_in_install_location() {
         ]
     );
 }
+
+/// Test that when get_environments is called with a child environment under the `envs` folder,
+/// it also discovers the parent conda install (base environment) and all sibling environments.
+/// This is the fix for https://github.com/microsoft/python-environment-tools/issues/236
+/// where the base conda environment wasn't discovered when only child envs were listed
+/// in environments.txt (e.g., from Homebrew Cask installs like /opt/homebrew/Caskroom/miniforge/base).
+#[cfg(unix)]
+#[test]
+fn list_conda_envs_discovers_base_from_child_env() {
+    use common::resolve_test_path;
+    use pet_conda::environment_locations::get_environments;
+
+    // Call get_environments with a child environment path (not the install directory)
+    let child_env_path = resolve_test_path(&["unix", "anaconda3-2023.03", "envs", "myenv"]);
+
+    let mut locations = get_environments(&child_env_path);
+    locations.sort();
+
+    // Should discover not only the child env, but also the base env (conda install dir)
+    // and all sibling environments
+    assert_eq!(
+        locations,
+        vec![
+            resolve_test_path(&["unix", "anaconda3-2023.03"]),
+            resolve_test_path(&["unix", "anaconda3-2023.03", "envs", "env_python_3"]),
+            resolve_test_path(&["unix", "anaconda3-2023.03", "envs", "myenv"]),
+            resolve_test_path(&["unix", "anaconda3-2023.03", "envs", "without_python"]),
+        ]
+    );
+}
+
+/// Test that get_environments works correctly with an env_python_3 child environment
+/// (another sibling to verify the fix works for any child env under envs folder).
+#[cfg(unix)]
+#[test]
+fn list_conda_envs_discovers_base_from_another_child_env() {
+    use common::resolve_test_path;
+    use pet_conda::environment_locations::get_environments;
+
+    // Call get_environments with a different child environment path
+    let child_env_path = resolve_test_path(&["unix", "anaconda3-2023.03", "envs", "env_python_3"]);
+
+    let mut locations = get_environments(&child_env_path);
+    locations.sort();
+
+    // Should discover the base env and all sibling environments
+    assert_eq!(
+        locations,
+        vec![
+            resolve_test_path(&["unix", "anaconda3-2023.03"]),
+            resolve_test_path(&["unix", "anaconda3-2023.03", "envs", "env_python_3"]),
+            resolve_test_path(&["unix", "anaconda3-2023.03", "envs", "myenv"]),
+            resolve_test_path(&["unix", "anaconda3-2023.03", "envs", "without_python"]),
+        ]
+    );
+}