[Tests] Add tests for "quantization_w4a4_fp4" examples (#1715)

SUMMARY:
Adds tests for the example scripts in the
`examples/quantization_w4a4_fp4` folder.

TEST PLAN:
Internal examples test run with just the new tests:
https://github.com/neuralmagic/llm-compressor-testing/actions/runs/16831501387/job/47709542536

The failure appears to be a legitimate issue, not a test issue, and has
been reported.

---------

Signed-off-by: Derek Kozikowski <[email protected]>
Signed-off-by: Domenic Barbuzzi <[email protected]>
Signed-off-by: Domenic Barbuzzi <[email protected]>
Co-authored-by: Derek Kozikowski <[email protected]>

Author: dbarbuzzi

tests/examples/test_quantization_w4a4_fp4.py

@@ -0,0 +1,53 @@
+import json
+from pathlib import Path
+from typing import List
+
+import pytest
+
+from tests.examples.utils import (
+    copy_and_run_script,
+    gen_cmd_fail_message,
+    requires_gpu_count,
+)
+
+
+@pytest.fixture
+def example_dir() -> str:
+    return "examples/quantization_w4a4_fp4"
+
+
+@requires_gpu_count(1)
+@pytest.mark.example
+class TestQuantizationW4A4_FP4:
+    """
+    Tests for examples in the "quantization_w4a4_fp4" example folder.
+    """
+
+    @pytest.mark.parametrize(
+        "script_filename",
+        [
+            "llama3_example.py",
+            "llama4_example.py",
+            "qwen_30b_a3b.py",
+        ],
+    )
+    def test_quantization_w4a4_fp4_example_script(
+        self, script_filename: str, example_dir: str, tmp_path: Path
+    ):
+        """
+        Tests the example scripts in the folder.
+        """
+        command, result = copy_and_run_script(tmp_path, example_dir, script_filename)
+
+        assert result.returncode == 0, gen_cmd_fail_message(command, result)
+
+        # verify the expected directory was generated
+        nvfp4_dirs: List[Path] = [p for p in tmp_path.rglob("*-NVFP4") if p.is_dir()]
+        assert (
+            len(nvfp4_dirs)
+        ) == 1, f"did not find exactly one generated folder: {nvfp4_dirs}"
+
+        # verify the format in the generated config
+        config_json = json.loads((nvfp4_dirs[0] / "config.json").read_text())
+        config_format = config_json["quantization_config"]["format"]
+        assert config_format == "nvfp4-pack-quantized"