test: add Mac python.org locator coverage (#430)

Adds focused direct coverage for the Mac python.org locator while
continuing the #389 coverage work.

- Adds deterministic tests for python.org framework path matching,
locator metadata, and non-macOS rejection.
- Narrows python.org classification to interpreter-shaped framework
paths under
/Library/Frameworks/Python.framework/Versions/{version}/bin/.
- Covers false positives for python-config scripts, nested bin paths,
Homebrew framework paths, and unrelated frameworks.

Validation:
- cargo fmt --all
- wsl bash -lc 'cd /mnt/c/GIT/projects/python-environment-tools && cargo
test -p pet-mac-python-org'
- wsl bash -lc 'cd /mnt/c/GIT/projects/python-environment-tools && cargo
clippy --all -- -D warnings'

Refs #389

Author: karthiknadig

crates/pet-mac-python-org/src/lib.rs

@@ -46,10 +46,7 @@ impl Locator for MacPythonOrg {
         }
 
         let mut executable = resolve_symlink(&env.executable).unwrap_or(env.executable.clone());
-        if !executable
-            .to_string_lossy()
-            .starts_with("/Library/Frameworks/Python.framework/Versions/")
-        {
+        if !is_mac_python_org_framework_path(&executable) {
             return None;
         }
 
@@ -166,3 +163,197 @@ impl Locator for MacPythonOrg {
         }
     }
 }
+
+fn is_mac_python_org_framework_path(executable: &std::path::Path) -> bool {
+    let Ok(framework_entry) =
+        executable.strip_prefix("/Library/Frameworks/Python.framework/Versions")
+    else {
+        return false;
+    };
+
+    let mut framework_parts = framework_entry.components();
+    matches!(
+        framework_parts.next(),
+        Some(std::path::Component::Normal(version))
+            if version.to_str().is_some_and(is_macos_framework_version_dir)
+    ) && matches!(
+        framework_parts.next(),
+        Some(std::path::Component::Normal(part)) if part == std::ffi::OsStr::new("bin")
+    ) && matches!(
+        framework_parts.next(),
+        Some(std::path::Component::Normal(executable_name))
+            if executable_name.to_str().is_some_and(is_macos_python_executable_name)
+    ) && framework_parts.next().is_none()
+}
+
+fn is_macos_python_executable_name(executable: &str) -> bool {
+    if executable == "python" || executable == "python3" {
+        return true;
+    }
+
+    let Some(minor) = executable.strip_prefix("python3.") else {
+        return false;
+    };
+
+    !minor.is_empty() && minor.chars().all(|ch| ch.is_ascii_digit())
+}
+
+fn is_macos_framework_version_dir(version: &str) -> bool {
+    if version == "Current" {
+        return true;
+    }
+
+    let mut parts = version.split('.');
+    parts
+        .next()
+        .is_some_and(|major| !major.is_empty() && major.chars().all(|ch| ch.is_ascii_digit()))
+        && parts
+            .next()
+            .is_some_and(|minor| !minor.is_empty() && minor.chars().all(|ch| ch.is_ascii_digit()))
+        && parts.next().is_none()
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use pet_core::Locator;
+    use std::path::Path;
+
+    #[test]
+    fn locator_metadata_matches_python_org_kind() {
+        let locator = MacPythonOrg::new();
+
+        assert_eq!(locator.get_kind(), LocatorKind::MacPythonOrg);
+        assert_eq!(
+            locator.supported_categories(),
+            vec![PythonEnvironmentKind::MacPythonOrg]
+        );
+    }
+
+    #[test]
+    fn framework_path_accepts_versioned_python3() {
+        assert!(is_mac_python_org_framework_path(Path::new(
+            "/Library/Frameworks/Python.framework/Versions/3.12/bin/python3"
+        )));
+    }
+
+    #[test]
+    fn framework_path_accepts_unversioned_python() {
+        assert!(is_mac_python_org_framework_path(Path::new(
+            "/Library/Frameworks/Python.framework/Versions/3.12/bin/python"
+        )));
+    }
+
+    #[test]
+    fn framework_path_accepts_versioned_python_executable() {
+        assert!(is_mac_python_org_framework_path(Path::new(
+            "/Library/Frameworks/Python.framework/Versions/3.12/bin/python3.12"
+        )));
+    }
+
+    #[test]
+    fn framework_path_accepts_current_python() {
+        assert!(is_mac_python_org_framework_path(Path::new(
+            "/Library/Frameworks/Python.framework/Versions/Current/bin/python3"
+        )));
+    }
+
+    #[test]
+    fn framework_path_rejects_non_python_file() {
+        assert!(!is_mac_python_org_framework_path(Path::new(
+            "/Library/Frameworks/Python.framework/Versions/3.12/Resources/Info.plist"
+        )));
+    }
+
+    #[test]
+    fn framework_path_rejects_python_config_script() {
+        assert!(!is_mac_python_org_framework_path(Path::new(
+            "/Library/Frameworks/Python.framework/Versions/3.12/bin/python-config"
+        )));
+    }
+
+    #[test]
+    fn framework_path_rejects_versioned_python_config_script() {
+        assert!(!is_mac_python_org_framework_path(Path::new(
+            "/Library/Frameworks/Python.framework/Versions/3.12/bin/python3.12-config"
+        )));
+    }
+
+    #[test]
+    fn framework_path_rejects_patch_version_python_name() {
+        assert!(!is_mac_python_org_framework_path(Path::new(
+            "/Library/Frameworks/Python.framework/Versions/3.12/bin/python3.12.0"
+        )));
+    }
+
+    #[test]
+    fn framework_path_rejects_compact_version_python_name() {
+        assert!(!is_mac_python_org_framework_path(Path::new(
+            "/Library/Frameworks/Python.framework/Versions/3.12/bin/python312"
+        )));
+    }
+
+    #[test]
+    fn framework_path_rejects_python2_name() {
+        assert!(!is_mac_python_org_framework_path(Path::new(
+            "/Library/Frameworks/Python.framework/Versions/3.12/bin/python2"
+        )));
+    }
+
+    #[test]
+    fn framework_path_rejects_patch_version_dir() {
+        assert!(!is_mac_python_org_framework_path(Path::new(
+            "/Library/Frameworks/Python.framework/Versions/3.12.0/bin/python3"
+        )));
+    }
+
+    #[test]
+    fn framework_path_rejects_invalid_version_dir() {
+        assert!(!is_mac_python_org_framework_path(Path::new(
+            "/Library/Frameworks/Python.framework/Versions/Foo/bin/python3"
+        )));
+    }
+
+    #[test]
+    fn framework_path_rejects_other_framework() {
+        assert!(!is_mac_python_org_framework_path(Path::new(
+            "/Library/Frameworks/Other.framework/Versions/3.12/bin/python3"
+        )));
+    }
+
+    #[test]
+    fn framework_path_rejects_non_library_path() {
+        assert!(!is_mac_python_org_framework_path(Path::new(
+            "/tmp/Python.framework/Versions/3.12/bin/python3"
+        )));
+    }
+
+    #[test]
+    fn framework_path_rejects_homebrew_framework_path() {
+        assert!(!is_mac_python_org_framework_path(Path::new(
+            "/opt/homebrew/Cellar/python@3.12/3.12.1/Frameworks/Python.framework/Versions/3.12/bin/python3"
+        )));
+    }
+
+    #[test]
+    fn framework_path_rejects_nested_bin_entry() {
+        assert!(!is_mac_python_org_framework_path(Path::new(
+            "/Library/Frameworks/Python.framework/Versions/3.12/bin/nested/python3"
+        )));
+    }
+
+    #[cfg(not(target_os = "macos"))]
+    #[test]
+    fn try_from_rejects_python_org_path_off_macos() {
+        let locator = MacPythonOrg::new();
+        let env = PythonEnv::new(
+            PathBuf::from("/Library/Frameworks/Python.framework/Versions/3.12/bin/python3"),
+            Some(PathBuf::from(
+                "/Library/Frameworks/Python.framework/Versions/3.12",
+            )),
+            Some("3.12.0".to_string()),
+        );
+
+        assert!(locator.try_from(&env).is_none());
+    }
+}