diff --git a/libs/langchain/tests/unit_tests/chains/rl_chain/test_pick_best_chain_call.py b/libs/langchain/tests/unit_tests/chains/rl_chain/test_pick_best_chain_call.py
index 7bca6b470d..1b882e932d 100644
--- a/libs/langchain/tests/unit_tests/chains/rl_chain/test_pick_best_chain_call.py
+++ b/libs/langchain/tests/unit_tests/chains/rl_chain/test_pick_best_chain_call.py
@@ -23,7 +23,11 @@ def setup() -> tuple:
 @pytest.mark.requires("vowpal_wabbit_next", "sentence_transformers")
 def test_multiple_ToSelectFrom_throws() -> None:
     llm, PROMPT = setup()
-    chain = pick_best_chain.PickBest.from_llm(llm=llm, prompt=PROMPT)
+    chain = pick_best_chain.PickBest.from_llm(
+        llm=llm,
+        prompt=PROMPT,
+        feature_embedder=pick_best_chain.PickBestFeatureEmbedder(model=MockEncoder()),
+    )
     actions = ["0", "1", "2"]
     with pytest.raises(ValueError):
         chain.run(
@@ -36,7 +40,11 @@ def test_multiple_ToSelectFrom_throws() -> None:
 @pytest.mark.requires("vowpal_wabbit_next", "sentence_transformers")
 def test_missing_basedOn_from_throws() -> None:
     llm, PROMPT = setup()
-    chain = pick_best_chain.PickBest.from_llm(llm=llm, prompt=PROMPT)
+    chain = pick_best_chain.PickBest.from_llm(
+        llm=llm,
+        prompt=PROMPT,
+        feature_embedder=pick_best_chain.PickBestFeatureEmbedder(model=MockEncoder()),
+    )
     actions = ["0", "1", "2"]
     with pytest.raises(ValueError):
         chain.run(action=rl_chain.ToSelectFrom(actions))
@@ -45,7 +53,11 @@ def test_missing_basedOn_from_throws() -> None:
 @pytest.mark.requires("vowpal_wabbit_next", "sentence_transformers")
 def test_ToSelectFrom_not_a_list_throws() -> None:
     llm, PROMPT = setup()
-    chain = pick_best_chain.PickBest.from_llm(llm=llm, prompt=PROMPT)
+    chain = pick_best_chain.PickBest.from_llm(
+        llm=llm,
+        prompt=PROMPT,
+        feature_embedder=pick_best_chain.PickBestFeatureEmbedder(model=MockEncoder()),
+    )
     actions = {"actions": ["0", "1", "2"]}
     with pytest.raises(ValueError):
         chain.run(
@@ -63,6 +75,7 @@ def test_update_with_delayed_score_with_auto_validator_throws() -> None:
         llm=llm,
         prompt=PROMPT,
         selection_scorer=rl_chain.AutoSelectionScorer(llm=auto_val_llm),
+        feature_embedder=pick_best_chain.PickBestFeatureEmbedder(model=MockEncoder()),
     )
     actions = ["0", "1", "2"]
     response = chain.run(
@@ -85,6 +98,7 @@ def test_update_with_delayed_score_force() -> None:
         llm=llm,
         prompt=PROMPT,
         selection_scorer=rl_chain.AutoSelectionScorer(llm=auto_val_llm),
+        feature_embedder=pick_best_chain.PickBestFeatureEmbedder(model=MockEncoder()),
     )
     actions = ["0", "1", "2"]
     response = chain.run(
@@ -104,7 +118,10 @@ def test_update_with_delayed_score_force() -> None:
 def test_update_with_delayed_score() -> None:
     llm, PROMPT = setup()
     chain = pick_best_chain.PickBest.from_llm(
-        llm=llm, prompt=PROMPT, selection_scorer=None
+        llm=llm,
+        prompt=PROMPT,
+        selection_scorer=None,
+        feature_embedder=pick_best_chain.PickBestFeatureEmbedder(model=MockEncoder()),
     )
     actions = ["0", "1", "2"]
     response = chain.run(
@@ -128,7 +145,10 @@ def test_user_defined_scorer() -> None:
             return score
 
     chain = pick_best_chain.PickBest.from_llm(
-        llm=llm, prompt=PROMPT, selection_scorer=CustomSelectionScorer()
+        llm=llm,
+        prompt=PROMPT,
+        selection_scorer=CustomSelectionScorer(),
+        feature_embedder=pick_best_chain.PickBestFeatureEmbedder(model=MockEncoder()),
     )
     actions = ["0", "1", "2"]
     response = chain.run(
@@ -239,7 +259,11 @@ def test_default_embeddings_mixed_w_explicit_user_embeddings() -> None:
 def test_default_no_scorer_specified() -> None:
     _, PROMPT = setup()
     chain_llm = FakeListChatModel(responses=[100])
-    chain = pick_best_chain.PickBest.from_llm(llm=chain_llm, prompt=PROMPT)
+    chain = pick_best_chain.PickBest.from_llm(
+        llm=chain_llm,
+        prompt=PROMPT,
+        feature_embedder=pick_best_chain.PickBestFeatureEmbedder(model=MockEncoder()),
+    )
     response = chain.run(
         User=rl_chain.BasedOn("Context"),
         action=rl_chain.ToSelectFrom(["0", "1", "2"]),
@@ -254,7 +278,10 @@ def test_default_no_scorer_specified() -> None:
 def test_explicitly_no_scorer() -> None:
     llm, PROMPT = setup()
     chain = pick_best_chain.PickBest.from_llm(
-        llm=llm, prompt=PROMPT, selection_scorer=None
+        llm=llm,
+        prompt=PROMPT,
+        selection_scorer=None,
+        feature_embedder=pick_best_chain.PickBestFeatureEmbedder(model=MockEncoder()),
     )
     response = chain.run(
         User=rl_chain.BasedOn("Context"),
@@ -274,6 +301,7 @@ def test_auto_scorer_with_user_defined_llm() -> None:
         llm=llm,
         prompt=PROMPT,
         selection_scorer=rl_chain.AutoSelectionScorer(llm=scorer_llm),
+        feature_embedder=pick_best_chain.PickBestFeatureEmbedder(model=MockEncoder()),
     )
     response = chain.run(
         User=rl_chain.BasedOn("Context"),
@@ -288,7 +316,11 @@ def test_auto_scorer_with_user_defined_llm() -> None:
 @pytest.mark.requires("vowpal_wabbit_next", "sentence_transformers")
 def test_calling_chain_w_reserved_inputs_throws() -> None:
     llm, PROMPT = setup()
-    chain = pick_best_chain.PickBest.from_llm(llm=llm, prompt=PROMPT)
+    chain = pick_best_chain.PickBest.from_llm(
+        llm=llm,
+        prompt=PROMPT,
+        feature_embedder=pick_best_chain.PickBestFeatureEmbedder(model=MockEncoder()),
+    )
     with pytest.raises(ValueError):
         chain.run(
             User=rl_chain.BasedOn("Context"),