Making model test case consistently random (#5278)

CHANGELOG.md

@@ -22,7 +22,8 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 - Fixed Broken link in `allennlp.fairness.fairness_metrics.Separation` docs
 - Ensured all `allennlp` submodules are imported with `allennlp.common.plugins.import_plugins()`.
 - Fixed `IndexOutOfBoundsException` in `MultiOptimizer` when checking if optimizer received any parameters.
-- Removed confusing zero mask from VilBERT
+- Removed confusing zero mask from VilBERT.
+- Ensured `ensure_model_can_train_save_and_load` is consistently random.
 
 ### Changed
 

allennlp/common/testing/model_test_case.py

@@ -119,11 +119,6 @@ def ensure_model_can_train_save_and_load(
             Specifies which loss to test. For example, which_loss may be "adversary_loss" for
             `adversarial_bias_mitigator`.
         """
-        if seed is not None:
-            random.seed(seed)
-            numpy.random.seed(seed)
-            torch.manual_seed(seed)
-
         save_dir = self.TEST_DIR / "save_and_load_test"
         archive_file = save_dir / "model.tar.gz"
         model = train_model_from_file(param_file, save_dir, overrides=overrides)
@@ -158,12 +153,22 @@ def ensure_model_can_train_save_and_load(
         data_loader_params["shuffle"] = False
         data_loader_params2 = Params(copy.deepcopy(data_loader_params.as_dict()))
 
+        if seed is not None:
+            random.seed(seed)
+            numpy.random.seed(seed)
+            torch.manual_seed(seed)
+
         print("Reading with original model")
         data_loader = DataLoader.from_params(
             params=data_loader_params, reader=reader, data_path=params["validation_data_path"]
         )
         data_loader.index_with(model.vocab)
 
+        if seed is not None:
+            random.seed(seed)
+            numpy.random.seed(seed)
+            torch.manual_seed(seed)
+
         print("Reading with loaded model")
         data_loader2 = DataLoader.from_params(
             params=data_loader_params2, reader=reader, data_path=params["validation_data_path"]