1 files changed, 44 insertions, 0 deletions
diff --git a/tests/unit/test_pyproject_config.py b/tests/unit/test_pyproject_config.py
new file mode 100644
index 000000000..9937f3880
--- /dev/null
+++ b/tests/unit/test_pyproject_config.py
@@ -0,0 +1,44 @@
+import pytest
+
+from pip._internal.commands import create_command
+
+
+@pytest.mark.parametrize(
+    ("command", "expected"),
+    [
+        ("install", True),
+        ("wheel", True),
+        ("freeze", False),
+    ],
+)
+def test_supports_config(command: str, expected: bool) -> None:
+    c = create_command(command)
+    options, _ = c.parse_args([])
+    assert hasattr(options, "config_settings") == expected
+
+
+def test_set_config_value_true() -> None:
+    i = create_command("install")
+    # Invalid argument exits with an error
+    with pytest.raises(SystemExit):
+        options, _ = i.parse_args(["xxx", "--config-settings", "x"])
+
+
+def test_set_config_value() -> None:
+    i = create_command("install")
+    options, _ = i.parse_args(["xxx", "--config-settings", "x=hello"])
+    assert options.config_settings == {"x": "hello"}
+
+
+def test_set_config_empty_value() -> None:
+    i = create_command("install")
+    options, _ = i.parse_args(["xxx", "--config-settings", "x="])
+    assert options.config_settings == {"x": ""}
+
+
+def test_replace_config_value() -> None:
+    i = create_command("install")
+    options, _ = i.parse_args(
+        ["xxx", "--config-settings", "x=hello", "--config-settings", "x=world"]
+    )
+    assert options.config_settings == {"x": "world"}