Make container-engine a build (non-global) option (#1792)

unit_test/validate_schema_test.py

@@ -20,11 +20,39 @@ def test_validate_default_schema():
     assert validator(example) is not None
 
 
-def test_validate_bad_container_engine():
+def test_validate_container_engine():
+    """
+    This test checks container engine can be overridden - it used to be a
+    global option but is now a build option.
+    """
+
     example = tomllib.loads(
         """
+        [tool.cibuildwheel]
+        container-engine = "docker"
+
         [tool.cibuildwheel.linux]
         container-engine = "docker"
+
+        [[tool.cibuildwheel.overrides]]
+        select = "*_x86_64"
+        container-engine = "docker; create_args: --platform linux/arm64/v8"
+        """
+    )
+
+    validator = validate_pyproject.api.Validator()
+    assert validator(example) is not None
+
+
+@pytest.mark.parametrize("platform", ["macos", "windows"])
+def test_validate_bad_container_engine(platform: str):
+    """
+    container-engine is not a valid option for macos or windows
+    """
+    example = tomllib.loads(
+        f"""
+        [tool.cibuildwheel.{platform}]
+        container-engine = "docker"
         """
     )