Add an integration test of installing a project with a local PEP 517 backend

Author: takluyver

tests/data/packages/pep517_wrapper_buildsys/mybuildsys.py

@@ -0,0 +1,15 @@
+import os
+
+from setuptools.build_meta import build_sdist
+from setuptools.build_meta import build_wheel as setuptools_build_wheel
+from setuptools.build_meta import (get_requires_for_build_sdist,
+                                   get_requires_for_build_wheel,
+                                   prepare_metadata_for_build_wheel)
+
+
+def build_wheel(*a, **kw):
+    # Create the marker file to record that the hook was called
+    with open(os.environ['PIP_TEST_MARKER_FILE'], 'wb'):
+        pass
+
+    return setuptools_build_wheel(*a, **kw)

tests/data/packages/pep517_wrapper_buildsys/pyproject.toml

@@ -0,0 +1,4 @@
+[build-system]
+requires = [ "setuptools" ]
+build-backend = "mybuildsys"  # setuptools.build_meta
+backend-path = ["."]

tests/data/packages/pep517_wrapper_buildsys/setup.cfg

@@ -0,0 +1,3 @@
+[metadata]
+name = pep517-wrapper-buildsys
+version = 1.0

tests/data/packages/pep517_wrapper_buildsys/setup.py

@@ -0,0 +1,3 @@
+from setuptools import setup
+
+setup()

tests/functional/test_install.py

@@ -1339,6 +1339,21 @@ def test_install_no_binary_builds_pep_517_wheel(script, data, with_wheel):
     assert "Running setup.py install for pep517-set" not in str(res), str(res)
 
 
+@pytest.mark.network
+def test_install_no_binary_uses_local_backend(
+        script, data, with_wheel, tmpdir):
+    to_install = data.packages.joinpath('pep517_wrapper_buildsys')
+    script.environ['PIP_TEST_MARKER_FILE'] = marker = str(tmpdir / 'marker')
+    res = script.pip(
+        'install', '--no-binary=:all:', '-f', data.find_links, to_install
+    )
+    expected = "Successfully installed pep517-wrapper-buildsys"
+    # Must have installed the package
+    assert expected in str(res), str(res)
+
+    assert os.path.isfile(marker), "Local PEP 517 backend not used"
+
+
 def test_install_no_binary_disables_cached_wheels(script, data, with_wheel):
     # Seed the cache
     script.pip(