Fix local plugin installation (#1129)

* test: add test for lektor.packages.install_local_package

* fix(packages): fix local plugin installation

The most recent version of pip (23.1) removes support for the
`--install-option` parameter to `pip install`.  This breaks our
`install_local_package` function, which uses `--install-option`
because `pip install --target` didn't used to work with `pip install
--editable`.

As it turns out, recent versions of pip support the use of `--target`
with `--editable`.  So here we make use of that.

Note that this also relieves us of the need to parse our local
plugin requirements ourselves (thus, hopefully, fixing #865.)

CHANGES.md

@@ -4,12 +4,20 @@ These are all the changes in Lektor since the first public release.
 
 ## 3.3.9 (unreleased)
 
+### Bit-Rot
+
+- Fix installation of local plugins (from the `packages/`
+  subdirectory). This was broken by release 23.1 of `pip` which
+  dropped support for the `--install-option` flag to `pip install`.
+  ([#1129], [#1127])
+
 ### Bugs
 
 - Implement better input validation for the date/time-formatting jinja
   filters. Prior to this, passing a `jinja2.Undefined` value to the
   `date`, `time`, or `datetime` filters would elicit an assertion
   error. ([#1122], [#1121])
+
 - Fix for spurious rebuilds. Recent versions of watchdog (>=2.3.0)
   enabled tracking of IN_OPEN events. These fire when a file is opened
   — even just for reading. Now we're pickier about only responding to
@@ -18,6 +26,8 @@ These are all the changes in Lektor since the first public release.
 [#1117]: https://github.com/lektor/lektor/pull/1117
 [#1121]: https://github.com/lektor/lektor/issues/1121
 [#1122]: https://github.com/lektor/lektor/pull/1122
+[#1127]: https://github.com/lektor/lektor/issues/1127
+[#1129]: https://github.com/lektor/lektor/pull/1129
 
 ## 3.3.8 (2023-02-28)
 

lektor/packages.py

@@ -3,7 +3,6 @@
 import shutil
 import site
 import sys
-import tempfile
 from subprocess import PIPE
 
 import click
@@ -104,53 +103,21 @@ def download_and_install_package(
 def install_local_package(package_root, path):
     """This installs a local dependency of a package."""
     # XXX: windows
-    env = dict(os.environ)
-    env["PYTHONPATH"] = package_root
-
-    # Step 1: generate egg info and link us into the target folder.
     rv = portable_popen(
         [
             sys.executable,
             "-m",
             "pip",
             "install",
+            "--target",
+            package_root,
             "--editable",
             path,
-            "--install-option=--install-dir=%s" % package_root,
-            "--no-deps",
         ],
-        env=env,
     ).wait()
     if rv != 0:
         raise RuntimeError("Failed to install local package")
 
-    # Step 2: generate the egg info into a temp folder to find the
-    # requirements.
-    tmp = tempfile.mkdtemp()
-    try:
-        rv = portable_popen(
-            [
-                sys.executable,
-                "setup.py",
-                "--quiet",
-                "egg_info",
-                "--quiet",
-                "--egg-base",
-                tmp,
-            ],
-            cwd=path,
-        ).wait()
-        dirs = os.listdir(tmp)
-        if rv != 0 or len(dirs) != 1:
-            raise RuntimeError("Failed to create egg info for local package.")
-        requires = os.path.join(tmp, dirs[0], "requires.txt")
-
-        # We have dependencies, install them!
-        if os.path.isfile(requires):
-            download_and_install_package(package_root, requirements_file=requires)
-    finally:
-        shutil.rmtree(tmp)
-
 
 def get_package_info(path):
     """Returns the name of a package at a path."""

setup.cfg

@@ -45,11 +45,11 @@ install_requires =
     Jinja2>=3.0
     markupsafe
     mistune>=0.7.0,<2
-    pip
+    pip>=21.1
     python-slugify
     pytz
     requests
-    setuptools
+    setuptools>=45.2
     watchdog
     Werkzeug<3
 

tests/setup_py-dummy-plugin/lektor_dummy_plugin.py

@@ -0,0 +1,9 @@
+"""Dummy test plugin"""
+from lektor.pluginsystem import Plugin
+
+
+class DummyPlugin(Plugin):
+    """Dummy test plugin."""
+
+    # pylint: disable=too-few-public-methods
+    name = "dummy"

tests/setup_py-dummy-plugin/setup.py

@@ -0,0 +1,13 @@
+from setuptools import setup
+
+setup(
+    name="lektor-dummy-plugin",
+    description="setup.py test plugin",
+    version="0.1a42",
+    py_modules=["lektor_dummy_plugin"],
+    entry_points={
+        "lektor.plugins": [
+            "dummy-plugin = lektor_dummy_plugin:DummyPlugin",
+        ]
+    },
+)

tests/test_packages.py

@@ -0,0 +1,18 @@
+import os
+from pathlib import Path
+
+import pytest
+
+from lektor.packages import add_site
+from lektor.packages import install_local_package
+from lektor.pluginsystem import load_plugins
+
+
+@pytest.mark.usefixtures("save_sys_path")
+def test_install_local_package(tmp_path):
+    package_root = os.fspath(tmp_path / "package_root")
+    dummy_plugin_path = os.fspath(Path(__file__).parent / "setup_py-dummy-plugin")
+    install_local_package(package_root, dummy_plugin_path)
+    add_site(package_root)
+    plugins = load_plugins()
+    assert plugins["dummy-plugin"].name == "dummy"