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fix: process .pth files in activate_venv/1 and fix deactivate_venv/0 #8

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fix: process .pth files in activate_venv/1 and fix deactivate_venv/0 #8

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12 changes: 12 additions & 0 deletions CHANGELOG.md
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Original file line number Diff line number Diff line change
@@ -1,5 +1,17 @@
# Changelog

## Unreleased

### Fixed

- **`activate_venv/1` now processes `.pth` files** - Uses `site.addsitedir()` instead of
`sys.path.insert()` so that editable installs (uv, pip -e, poetry) work correctly.
New paths are moved to the front of `sys.path` for proper priority.

- **`deactivate_venv/0` now restores `sys.path`** - The previous implementation used
`py:eval` with semicolon-separated statements which silently failed (eval only accepts
expressions). Switched to `py:exec` for correct statement execution.

## 1.8.1 (2026-02-25)

### Fixed
Expand Down
29 changes: 20 additions & 9 deletions src/py.erl
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Expand Up @@ -490,6 +490,11 @@ parallel(Calls) when is_list(Calls) ->
%% This modifies sys.path to use packages from the specified venv.
%% The venv path should be the root directory (containing bin/lib folders).
%%
%% `.pth' files in the venv's site-packages directory are processed, so
%% editable installs created by uv, pip, or any PEP 517/660 compliant tool
%% work correctly. New paths are inserted at the front of sys.path so that
%% venv packages take priority over system packages.
%%
%% Example:
%% ```
%% ok = py:activate_venv(<<"/path/to/myenv">>).
Expand All @@ -504,12 +509,16 @@ activate_venv(VenvPath) ->
case eval(<<"__import__('os').path.isdir(sp)">>, #{sp => SitePackages}) of
{ok, true} ->
%% Save original path if not already saved
_ = eval(<<"setattr(__import__('sys'), '_original_path', __import__('sys').path.copy()) if not hasattr(__import__('sys'), '_original_path') else None">>),
{ok, _} = eval(<<"setattr(__import__('sys'), '_original_path', __import__('sys').path.copy()) if not hasattr(__import__('sys'), '_original_path') else None">>),
%% Set venv info
_ = eval(<<"setattr(__import__('sys'), '_active_venv', vp)">>, #{vp => VenvBin}),
_ = eval(<<"setattr(__import__('sys'), '_venv_site_packages', sp)">>, #{sp => SitePackages}),
%% Add to sys.path
_ = eval(<<"__import__('sys').path.insert(0, sp) if sp not in __import__('sys').path else None">>, #{sp => SitePackages}),
{ok, _} = eval(<<"setattr(__import__('sys'), '_active_venv', vp)">>, #{vp => VenvBin}),
{ok, _} = eval(<<"setattr(__import__('sys'), '_venv_site_packages', sp)">>, #{sp => SitePackages}),
%% Add site-packages and process .pth files (editable installs)
ok = exec(<<"import site as _site, sys as _sys\n"
"_b = frozenset(_sys.path)\n"
"_site.addsitedir(_sys._venv_site_packages)\n"
"_sys.path[:] = [p for p in _sys.path if p not in _b] + [p for p in _sys.path if p in _b]\n"
"del _site, _sys, _b\n">>),
ok;
{ok, false} ->
{error, {invalid_venv, SitePackages}};
Expand All @@ -523,10 +532,12 @@ activate_venv(VenvPath) ->
deactivate_venv() ->
case eval(<<"hasattr(__import__('sys'), '_original_path')">>) of
{ok, true} ->
_ = eval(<<"__import__('sys').path.clear(); __import__('sys').path.extend(__import__('sys')._original_path)">>),
_ = eval(<<"delattr(__import__('sys'), '_original_path')">>),
_ = eval(<<"delattr(__import__('sys'), '_active_venv') if hasattr(__import__('sys'), '_active_venv') else None">>),
_ = eval(<<"delattr(__import__('sys'), '_venv_site_packages') if hasattr(__import__('sys'), '_venv_site_packages') else None">>),
ok = exec(<<"import sys as _sys\n"
"_sys.path[:] = _sys._original_path\n"
"del _sys\n">>),
{ok, _} = eval(<<"delattr(__import__('sys'), '_original_path')">>),
{ok, _} = eval(<<"delattr(__import__('sys'), '_active_venv') if hasattr(__import__('sys'), '_active_venv') else None">>),
{ok, _} = eval(<<"delattr(__import__('sys'), '_venv_site_packages') if hasattr(__import__('sys'), '_venv_site_packages') else None">>),
ok;
{ok, false} ->
ok;
Expand Down
44 changes: 43 additions & 1 deletion test/py_SUITE.erl
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Expand Up @@ -37,6 +37,7 @@
test_subinterp_supported/1,
test_parallel_execution/1,
test_venv/1,
test_venv_pth/1,
%% New scalability tests
test_execution_mode/1,
test_num_executors/1,
Expand Down Expand Up @@ -87,6 +88,7 @@ all() ->
test_subinterp_supported,
test_parallel_execution,
test_venv,
test_venv_pth,
%% Scalability tests
test_execution_mode,
test_num_executors,
Expand Down Expand Up @@ -634,11 +636,16 @@ test_venv(_Config) ->
true = is_binary(maps:get(<<"venv_path">>, Info)),
true = is_binary(maps:get(<<"site_packages">>, Info)),

%% site-packages must be in sys.path and at position 0
{ok, true} = py:eval(<<"sp in __import__('sys').path">>, #{sp => SitePackages}),
{ok, 0} = py:eval(<<"__import__('sys').path.index(sp)">>, #{sp => SitePackages}),

%% Deactivate
ok = py:deactivate_venv(),

%% Verify deactivated
%% Verify deactivated: venv_info and sys.path both restored
{ok, #{<<"active">> := false}} = py:venv_info(),
{ok, false} = py:eval(<<"sp in __import__('sys').path">>, #{sp => SitePackages}),

%% Test error case - invalid path
{error, _} = py:activate_venv(<<"/nonexistent/path">>),
Expand All @@ -648,6 +655,41 @@ test_venv(_Config) ->

ok.

test_venv_pth(_Config) ->
%% Verify .pth files are processed (editable installs)
TmpDir = <<"/tmp/erlang_python_test_venv_pth">>,
PkgSrc = <<"/tmp/erlang_python_test_pth_src">>,

{ok, PyVer} = py:eval(<<"f'python{__import__(\"sys\").version_info.major}.{__import__(\"sys\").version_info.minor}'">>),
SitePackages = <<TmpDir/binary, "/lib/", PyVer/binary, "/site-packages">>,

%% Create fake venv with a .pth file pointing at PkgSrc
{ok, _} = py:call(os, makedirs, [SitePackages], #{exist_ok => true}),
{ok, _} = py:call(os, makedirs, [PkgSrc], #{exist_ok => true}),
PthFile = <<SitePackages/binary, "/test_editable.pth">>,
{ok, _} = py:eval(<<"open(pf, 'w').write(pd + '\\n')">>, #{pf => PthFile, pd => PkgSrc}),

%% Drop a module in PkgSrc so we can verify it's importable
ModFile = <<PkgSrc/binary, "/ep_test_editable_mod.py">>,
{ok, _} = py:eval(<<"open(f, 'w').write('answer = 42\\n')">>, #{f => ModFile}),

{ok, false} = py:eval(<<"pd in __import__('sys').path">>, #{pd => PkgSrc}),

%% Activate and verify paths and import
ok = py:activate_venv(TmpDir),
{ok, 0} = py:eval(<<"__import__('sys').path.index(sp)">>, #{sp => SitePackages}),
{ok, 1} = py:eval(<<"__import__('sys').path.index(pd)">>, #{pd => PkgSrc}),
{ok, 42} = py:eval(<<"__import__('ep_test_editable_mod').answer">>),

%% Deactivate and verify cleanup
ok = py:deactivate_venv(),
{ok, false} = py:eval(<<"pd in __import__('sys').path">>, #{pd => PkgSrc}),
{ok, false} = py:eval(<<"sp in __import__('sys').path">>, #{sp => SitePackages}),

{ok, _} = py:call(shutil, rmtree, [TmpDir], #{ignore_errors => true}),
{ok, _} = py:call(shutil, rmtree, [PkgSrc], #{ignore_errors => true}),
ok.

%%% ============================================================================
%%% Scalability Tests
%%% ============================================================================
Expand Down