Prototype adapter XInput feasibility

tests/test_xinput_feasibility_native.py

@@ -0,0 +1,39 @@
+from __future__ import annotations
+
+import shutil
+import subprocess
+from pathlib import Path
+
+
+def host_compiler() -> str:
+    compiler = shutil.which("c++") or shutil.which("g++")
+    assert compiler is not None, "a host C++ compiler is required"
+    return compiler
+
+
+def test_xinput_feasibility_contracts(tmp_path: Path) -> None:
+    root = Path(__file__).resolve().parents[1]
+    compiler = host_compiler()
+    for instance_count in range(1, 5):
+        executable = tmp_path / f"xinput_feasibility_{instance_count}_test"
+        result = subprocess.run(
+            [
+                compiler,
+                "-std=c++17",
+                "-Wall",
+                "-Wextra",
+                "-Werror",
+                "-pedantic",
+                f"-DSWITCH_PICO_HID_INSTANCE_COUNT={instance_count}",
+                f"-I{root}",
+                str(root / "tests" / "xinput_feasibility_test.cpp"),
+                "-o",
+                str(executable),
+            ],
+            check=False,
+            cwd=root,
+            text=True,
+            capture_output=True,
+        )
+        assert result.returncode == 0, result.stderr
+        _ = subprocess.run([str(executable)], check=True, cwd=root)