TEST: Sanity check test for --allow-empty flag

test/test_0_basic.py

@@ -59,3 +59,20 @@ def test_build_identifiers(tmp_path):
     assert len(expected_wheels) == len(
         build_identifiers
     ), f"{expected_wheels} vs {build_identifiers}"
+
+
+def test_allow_empty(tmp_path, build_frontend_env):
+    project_dir = tmp_path / "project"
+    basic_project.generate(project_dir)
+
+    # Sanity check - --allow-empty should cause a no-op build to complete
+    # without error
+    build_frontend_env["CIBW_BUILD"] = "BUILD_NOTHING_AT_ALL"
+
+    # build the wheels
+    actual_wheels = utils.cibuildwheel_run(
+        project_dir, add_env=build_frontend_env,
+        add_args=["--allow-empty"])
+
+    # check that the expected wheels are produced
+    expected_wheels = utils.expected_wheels("spam", "0.1.0")

test/utils.py

@@ -44,7 +44,7 @@ def cibuildwheel_get_build_identifiers(project_path, env=None, *, prerelease_pyt
     return cmd_output.strip().split("\n")
 
 
-def cibuildwheel_run(project_path, package_dir=".", env=None, add_env=None, output_dir=None):
+def cibuildwheel_run(project_path, package_dir=".", env=None, add_env=None, output_dir=None, add_args=None):
     """
     Runs cibuildwheel as a subprocess, building the project at project_path.
 
@@ -57,6 +57,7 @@ def cibuildwheel_run(project_path, package_dir=".", env=None, add_env=None, outp
     :param add_env: environment used to update env
     :param output_dir: directory where wheels are saved. If None, a temporary
     directory will be used for the duration of the command.
+    :param add_args: Additional command-line arguments to pass to cibuildwheel.
     :return: list of built wheels (file names).
     """
     if env is None:
@@ -64,6 +65,9 @@ def cibuildwheel_run(project_path, package_dir=".", env=None, add_env=None, outp
         # If present in the host environment, remove the MACOSX_DEPLOYMENT_TARGET for consistency
         env.pop("MACOSX_DEPLOYMENT_TARGET", None)
 
+    if add_args is None:
+        add_args = []
+
     if add_env is not None:
         env.update(add_env)
 
@@ -77,7 +81,7 @@ def cibuildwheel_run(project_path, package_dir=".", env=None, add_env=None, outp
                 "--output-dir",
                 str(output_dir or tmp_output_dir),
                 str(package_dir),
-            ],
+            ] + add_args,
             env=env,
             cwd=project_path,
             check=True,