Add tests for pypa#104

.gitignore

@@ -4,3 +4,4 @@ __pycache__/
 .tox
 .pytest_cache
 doc/_build/
+*.egg-info/

tests/samples/test-for-issue-104/pyproject.toml

@@ -0,0 +1,3 @@
+[build-system]
+requires = ["setuptools", "wheel"]
+build-backend = "setuptools.build_meta"

tests/samples/test-for-issue-104/setup.py

@@ -0,0 +1,11 @@
+import sys
+from setuptools import setup
+from os import path, environ, listdir
+import json
+
+children = listdir(sys.path[0])
+out = path.join(environ['PEP517_ISSUE104_OUTDIR'], 'out.json')
+with open(out, 'w') as f:
+    json.dump(children, f)
+
+setup()

tests/test_call_hooks.py

@@ -7,6 +7,7 @@
 import toml
 import zipfile
 import sys
+import json
 
 from mock import Mock
 
@@ -151,3 +152,16 @@ def test_custom_python_executable(monkeypatch, tmpdir):
             hooks.get_requires_for_build_wheel()
         runner.assert_called_once()
         assert runner.call_args[0][0][0] == 'some-python'
+
+
+def test_issue_104():
+    hooks = get_hooks('test-for-issue-104')
+    with TemporaryDirectory() as outdir:
+        with modified_env({
+            'PYTHONPATH': BUILDSYS_PKGS,
+            'PEP517_ISSUE104_OUTDIR': outdir,
+        }):
+            hooks.get_requires_for_build_wheel({})
+        with open(pjoin(outdir, 'out.json')) as f:
+            children = json.load(f)
+    assert set(children) <= {'__init__.py', '_in_process.py', '__pycache__'}