Fix Python package version detection after upgrade in conda history

crates/pet-conda/src/package.rs

@@ -93,59 +93,75 @@ fn get_conda_package_info_from_history(path: &Path, name: &Package) -> Option<Co
     let package_entry = format!(":{}-", name.to_name());
 
     let history_contents = fs::read_to_string(history).ok()?;
-    for line in history_contents
+
+    // Filter to only include lines that:
+    // 1. Start with '+' (installed packages, not '-' for removed packages)
+    // 2. Contain the package entry (e.g., ":python-")
+    //
+    // We need the LAST matching entry because conda appends to history chronologically.
+    // When a package is upgraded, the old version is removed (-) and new version installed (+).
+    // The last '+' entry represents the currently installed version.
+    //
+    // Sample history for Python upgrade from 3.9.18 to 3.9.21:
+    //   +defaults::python-3.9.18-h123456_0     <- initial install
+    //   ...
+    //   -defaults::python-3.9.18-h123456_0     <- removed during upgrade
+    //   +defaults::python-3.9.21-h789abc_0     <- current version (we want this)
+    let matching_lines: Vec<&str> = history_contents
         .lines()
-        .filter(|l| l.contains(&package_entry))
-    {
-        // Sample entry in the history file
-        // +conda-forge/osx-arm64::psutil-5.9.8-py312he37b823_0
-        // +conda-forge/osx-arm64::python-3.12.2-hdf0ec26_0_cpython
-        // +conda-forge/osx-arm64::python_abi-3.12-4_cp312
-        let regex = get_package_version_history_regex(name);
-        if let Some(captures) = regex.captures(line) {
-            if let Some(version) = captures.get(1) {
-                if let Some(hash) = captures.get(2) {
-                    let package_path = format!(
-                        "{}-{}-{}.json",
-                        name.to_name(),
-                        version.as_str(),
-                        hash.as_str()
-                    );
-                    let package_path = path.join(package_path);
-                    let mut arch: Option<Architecture> = None;
-                    // Sample contents
-                    // {
-                    //   "build": "h966fe2a_2",
-                    //   "build_number": 2,
-                    //   "channel": "https://repo.anaconda.com/pkgs/main/win-64",
-                    //   "constrains": [],
-                    // }
-                    // 32bit channel is https://repo.anaconda.com/pkgs/main/win-32/
-                    // 64bit channel is "channel": "https://repo.anaconda.com/pkgs/main/osx-arm64",
-                    if let Ok(contents) = read_to_string(&package_path) {
-                        if let Ok(js) = serde_json::from_str::<CondaMetaPackageStructure>(&contents)
-                        {
-                            if let Some(channel) = js.channel {
-                                if channel.ends_with("64") {
-                                    arch = Some(Architecture::X64);
-                                } else if channel.ends_with("32") {
-                                    arch = Some(Architecture::X86);
-                                }
-                            }
-                            if let Some(version) = js.version {
-                                return Some(CondaPackageInfo {
-                                    package: name.clone(),
-                                    path: package_path,
-                                    version,
-                                    arch,
-                                });
-                            } else {
-                                warn!(
-                                    "Unable to find version for package {} in {:?}",
-                                    name, package_path
-                                );
+        .filter(|l| l.starts_with('+') && l.contains(&package_entry))
+        .collect();
+
+    // Get the last matching line (most recent installation)
+    let line = matching_lines.last()?;
+
+    // Sample entry in the history file
+    // +conda-forge/osx-arm64::psutil-5.9.8-py312he37b823_0
+    // +conda-forge/osx-arm64::python-3.12.2-hdf0ec26_0_cpython
+    // +conda-forge/osx-arm64::python_abi-3.12-4_cp312
+    let regex = get_package_version_history_regex(name);
+    if let Some(captures) = regex.captures(line) {
+        if let Some(version) = captures.get(1) {
+            if let Some(hash) = captures.get(2) {
+                let package_path = format!(
+                    "{}-{}-{}.json",
+                    name.to_name(),
+                    version.as_str(),
+                    hash.as_str()
+                );
+                let package_path = path.join(package_path);
+                let mut arch: Option<Architecture> = None;
+                // Sample contents
+                // {
+                //   "build": "h966fe2a_2",
+                //   "build_number": 2,
+                //   "channel": "https://repo.anaconda.com/pkgs/main/win-64",
+                //   "constrains": [],
+                // }
+                // 32bit channel is https://repo.anaconda.com/pkgs/main/win-32/
+                // 64bit channel is "channel": "https://repo.anaconda.com/pkgs/main/osx-arm64",
+                if let Ok(contents) = read_to_string(&package_path) {
+                    if let Ok(js) = serde_json::from_str::<CondaMetaPackageStructure>(&contents) {
+                        if let Some(channel) = js.channel {
+                            if channel.ends_with("64") {
+                                arch = Some(Architecture::X64);
+                            } else if channel.ends_with("32") {
+                                arch = Some(Architecture::X86);
                             }
                         }
+                        if let Some(version) = js.version {
+                            return Some(CondaPackageInfo {
+                                package: name.clone(),
+                                path: package_path,
+                                version,
+                                arch,
+                            });
+                        } else {
+                            warn!(
+                                "Unable to find version for package {} in {:?}",
+                                name, package_path
+                            );
+                        }
                     }
                 }
             }

crates/pet-conda/tests/package_test.rs

@@ -92,3 +92,33 @@ fn get_python_package_info_without_history() {
         ])
     );
 }
+
+/// Test that when Python is upgraded, we get the current (last installed) version,
+/// not the original (first installed) version.
+/// This is a regression test for https://github.com/microsoft/python-environment-tools/issues/239
+///
+/// The history file contains:
+///   +defaults::python-3.9.18-h1a28f6b_0  (initial install)
+///   -defaults::python-3.9.18-h1a28f6b_0  (removed during upgrade)
+///   +defaults::python-3.9.21-h789abc_0   (current version)
+///
+/// We should detect version 3.9.21, not 3.9.18.
+#[cfg(unix)]
+#[test]
+fn get_python_package_info_after_upgrade() {
+    let path: PathBuf = resolve_test_path(&["unix", "conda_env_with_python_upgrade"]);
+    let pkg = CondaPackageInfo::from(&path, &package::Package::Python).unwrap();
+
+    assert_eq!(pkg.package, package::Package::Python);
+    // Should be 3.9.21 (current version), NOT 3.9.18 (original version)
+    assert_eq!(pkg.version, "3.9.21".to_string());
+    assert_eq!(
+        pkg.path,
+        resolve_test_path(&[
+            "unix",
+            "conda_env_with_python_upgrade",
+            "conda-meta",
+            "python-3.9.21-h789abc_0.json"
+        ])
+    );
+}

crates/pet-conda/tests/unix/conda_env_with_python_upgrade/conda-meta/history

@@ -0,0 +1,21 @@
+==> 2024-01-15 10:00:00 <==
+# cmd: /home/user/miniforge3/bin/conda create -n waa python=3.9.18
++defaults::ca-certificates-2023.01.10-hca03da5_0
++defaults::openssl-1.1.1t-h1a28f6b_0
++defaults::python-3.9.18-h1a28f6b_0
++defaults::pip-22.3.1-py39hca03da5_0
++defaults::setuptools-65.6.3-py39hca03da5_0
++defaults::wheel-0.38.4-py39hca03da5_0
+# update specs: ['python=3.9.18']
+
+==> 2024-06-20 14:30:00 <==
+# cmd: /home/user/miniforge3/bin/conda update python
+-defaults::python-3.9.18-h1a28f6b_0
+-defaults::pip-22.3.1-py39hca03da5_0
+-defaults::setuptools-65.6.3-py39hca03da5_0
+-defaults::wheel-0.38.4-py39hca03da5_0
++defaults::python-3.9.21-h789abc_0
++defaults::pip-23.3.1-py39hca03da5_0
++defaults::setuptools-68.0.0-py39hca03da5_0
++defaults::wheel-0.41.2-py39hca03da5_0
+# update specs: ['python']

crates/pet-conda/tests/unix/conda_env_with_python_upgrade/conda-meta/python-3.9.21-h789abc_0.json

@@ -0,0 +1,13 @@
+{
+  "build": "h789abc_0",
+  "build_number": 0,
+  "channel": "https://repo.anaconda.com/pkgs/main/linux-64",
+  "constrains": [],
+  "depends": [],
+  "files": [],
+  "license": "PSF",
+  "name": "python",
+  "noarch": null,
+  "package_type": "conda",
+  "version": "3.9.21"
+}