[Testing] Add unit tests for Gemma3 model

tests/python/model/test_gemma3.py

@@ -0,0 +1,71 @@
+# pylint: disable=invalid-name,missing-docstring
+"""Unit tests for Gemma3 model architecture."""
+
+import pytest
+
+from mlc_llm.model import MODEL_PRESETS, MODELS
+
+
+def test_gemma3_model_registered():
+    """Verify Gemma3 model is in the registry."""
+    assert "gemma3" in MODELS, "gemma3 should be registered in MODELS"
+
+
+@pytest.mark.parametrize(
+    "model_name",
+    [
+        "gemma3_2b",
+        "gemma3_9b",
+    ],
+)
+def test_gemma3_creation(model_name: str):
+    """Test Gemma3 model creation and export to TVM IR.
+
+    Verifies:
+    - Config can be loaded from preset
+    - Model instance can be created
+    - Model exports to TVM IR successfully
+    - Named parameters are extracted
+    """
+    model_info = MODELS["gemma3"]
+    config = model_info.config.from_dict(MODEL_PRESETS[model_name])
+    model = model_info.model(config)
+    mod, named_params = model.export_tvm(
+        spec=model.get_default_spec(),  # type: ignore
+    )
+
+    # Verify export succeeded
+    assert mod is not None
+    assert len(named_params) > 0
+
+    # Optional: show module structure
+    mod.show(black_format=False)
+
+    # Print parameters for debugging
+    for name, param in named_params:
+        print(name, param.shape, param.dtype)
+
+
+def test_gemma3_config_validation():
+    """Test Gemma3 configuration has required fields."""
+    model_info = MODELS["gemma3"]
+    config = model_info.config.from_dict(MODEL_PRESETS["gemma3_2b"])
+
+    # Check required config parameters
+    assert hasattr(config, "hidden_size") and config.hidden_size > 0
+    assert hasattr(config, "num_hidden_layers") and config.num_hidden_layers > 0
+    assert hasattr(config, "num_attention_heads") and config.num_attention_heads > 0
+    assert hasattr(config, "vocab_size") and config.vocab_size > 0
+
+    print(
+        f"Gemma3 Config: hidden_size={config.hidden_size}, "
+        f"layers={config.num_hidden_layers}, "
+        f"heads={config.num_attention_heads}, "
+        f"vocab={config.vocab_size}"
+    )
+
+
+if __name__ == "__main__":
+    # Allow running tests directly
+    test_gemma3_creation("gemma3_2b")
+    test_gemma3_creation("gemma3_9b")