test: add Gradio UI smoke test and CI test job

.github/workflows/ci.yml

@@ -7,6 +7,24 @@ on:
     branches: [main]
 
 jobs:
+  test:
+    runs-on: ubuntu-latest
+
+    steps:
+      - name: Checkout code
+        uses: actions/checkout@v4
+
+      - name: Set up Python
+        uses: actions/setup-python@v5
+        with:
+          python-version: "3.11"
+
+      - name: Install test dependencies
+        run: pip install pytest "gradio>=4.0" "numpy>=1.24,<2"
+
+      - name: Run tests
+        run: pytest tests/
+
   build:
     runs-on: ubuntu-latest
 

tests/test_ui_smoke.py

@@ -0,0 +1,46 @@
+"""Smoke test: the Gradio UI builds without model files or ML libraries."""
+
+import importlib.util
+import sys
+from pathlib import Path
+from unittest.mock import MagicMock, patch
+
+import gradio as gr
+import pytest
+
+_APP_PATH = Path(__file__).parent.parent / "ui" / "app.py"
+
+
+def _load_ui_app():
+    """Execute ui/app.py in a fresh module with load_models stubbed out."""
+    sys.modules.pop("ui.app", None)
+    spec = importlib.util.spec_from_file_location("ui.app", _APP_PATH)
+    module = importlib.util.module_from_spec(spec)
+    with patch("refacer.models.load_models", return_value=MagicMock()):
+        spec.loader.exec_module(module)
+    return module
+
+
+@pytest.fixture(scope="module")
+def app():
+    return _load_ui_app()
+
+
+def test_demo_is_gradio_blocks(app):
+    assert isinstance(app.demo, gr.Blocks)
+
+
+def test_demo_has_run_button(app):
+    assert isinstance(app.run_btn, gr.Button)
+
+
+def test_demo_has_file_input(app):
+    assert isinstance(app.file_input, gr.File)
+
+
+def test_demo_has_gallery(app):
+    assert isinstance(app.gallery, gr.Gallery)
+
+
+def test_demo_has_log_output(app):
+    assert isinstance(app.log_output, gr.Textbox)