fix: fix the return type of DeepEval.get_model_def_script() for all backends (#5094)

For dpmodel and JAX, previously it returns str, but the type hint is
dict.
For PyTorch and Paddle, previously it returns dict, but the type hint is
str.
Now, all backends return dict, and the type hints are also dict.

Add a test to test it.

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## Summary by CodeRabbit

* **Bug Fixes**
* Corrected method return type annotations to improve code accuracy and
consistency across inference modules.

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settings.</sub>

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Author: njzjz

deepmd/dpmodel/infer/deep_eval.py

@@ -90,6 +90,7 @@ def __init__(
 
         model_data = load_dp_model(model_file)
         self.dp = BaseModel.deserialize(model_data["model"])
+        self.dp.model_def_script = json.dumps(model_data.get("model_def_script", {}))
         self.rcut = self.dp.get_rcut()
         self.type_map = self.dp.get_type_map()
         if isinstance(auto_batch_size, bool):

deepmd/jax/infer/deep_eval.py

@@ -104,7 +104,7 @@ def __init__(
                 stablehlo_atomic_virial_no_ghost=model_data["@variables"][
                     "stablehlo_atomic_virial_no_ghost"
                 ].tobytes(),
-                model_def_script=model_data["model_def_script"],
+                model_def_script=json.dumps(model_data["model_def_script"]),
                 **model_data["constants"],
             )
         elif model_file.endswith(".savedmodel"):

deepmd/pd/infer/deep_eval.py

@@ -726,7 +726,7 @@ def eval_typeebd(self) -> np.ndarray:
         typeebd = paddle.concat(out, axis=1)
         return to_numpy_array(typeebd)
 
-    def get_model_def_script(self) -> str:
+    def get_model_def_script(self) -> dict:
         """Get model definition script."""
         return self.model_def_script
 

deepmd/pt/infer/deep_eval.py

@@ -684,7 +684,7 @@ def eval_typeebd(self) -> np.ndarray:
         typeebd = torch.cat(out, dim=1)
         return to_numpy_array(typeebd)
 
-    def get_model_def_script(self) -> str:
+    def get_model_def_script(self) -> dict:
         """Get model definition script."""
         return self.model_def_script
 

source/tests/consistent/io/test_io.py

@@ -158,6 +158,7 @@ def test_deep_eval(self) -> None:
                 prefix + backend.suffixes[suffix_idx], reference_data
             )
             deep_eval = DeepEval(prefix + backend.suffixes[suffix_idx])
+            self.assertIsInstance(deep_eval.get_model_def_script(), dict)
             if deep_eval.get_dim_fparam() > 0:
                 fparam = np.ones((nframes, deep_eval.get_dim_fparam()))
             else: