Adding PEP 518 test

test/test_pep518.py

@@ -0,0 +1,44 @@
+import textwrap
+from . import test_projects
+from . import utils
+
+basic_project = test_projects.new_c_project(
+    setup_py_add=textwrap.dedent(
+        """
+        # Will fail if PEP 518 does work
+        import requests
+        assert requests.__version__ == "2.23.0", "Requests found but wrong version ({0})".format(requests.__version__)
+
+        # Just making sure environment is still set
+        import os
+        if os.environ.get("CIBUILDWHEEL", "0") != "1":
+            raise Exception("CIBUILDWHEEL environment variable is not set to 1")
+        """
+    )
+)
+
+basic_project.files[
+    "pyproject.toml"
+] = """
+[build-system]
+requires = [
+    "setuptools>=42",
+    "wheel",
+    "requests==2.23.0"
+]
+
+build-backend = "setuptools.build_meta"
+"""
+
+
+def test_pep518(tmp_path):
+
+    project_dir = tmp_path / "project"
+    basic_project.generate(project_dir)
+
+    # build the wheels
+    actual_wheels = utils.cibuildwheel_run(project_dir)
+
+    # check that the expected wheels are produced
+    expected_wheels = utils.expected_wheels("spam", "0.1.0")
+    assert set(actual_wheels) == set(expected_wheels)