From decab2fc8583076c1d24351cae6dab0c6302deff Mon Sep 17 00:00:00 2001
From: Om Borda <75739450+omborda2002@users.noreply.github.com>
Date: Fri, 3 Jul 2026 12:36:51 +0200
Subject: [PATCH 1/4] test: type-check test/components/embedders and add it to
 mypy config

---
 pyproject.toml                                            | 2 +-
 .../test_sentence_transformers_doc_image_embedder.py      | 4 ++--
 .../embedders/test_hugging_face_api_document_embedder.py  | 8 ++++----
 .../embedders/test_hugging_face_api_text_embedder.py      | 2 +-
 .../components/embedders/test_openai_document_embedder.py | 6 +++---
 test/components/embedders/test_openai_text_embedder.py    | 5 +++--
 .../test_sentence_transformers_document_embedder.py       | 5 +++--
 ...test_sentence_transformers_sparse_document_embedder.py | 5 +++--
 .../test_sentence_transformers_sparse_text_embedder.py    | 2 +-
 .../embedders/test_sentence_transformers_text_embedder.py | 3 ++-
 10 files changed, 23 insertions(+), 19 deletions(-)

diff --git a/pyproject.toml b/pyproject.toml
index 1b8da4e9367..6d365d4900a 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -163,7 +163,7 @@ integration-only-slow = 'pytest --maxfail=5 -m "integration and slow" {args:test
 all = 'pytest {args:test}'
 
 # TODO We want to eventually type the whole test folder
-types = "mypy --install-types --non-interactive --cache-dir=.mypy_cache/ {args:haystack test/core/ test/marshal/ test/testing/ test/tracing/ test/tools/ test/human_in_the_loop test/evaluation test/document_stores test/dataclasses test/utils/}"
+types = "mypy --install-types --non-interactive --cache-dir=.mypy_cache/ {args:haystack test/core/ test/marshal/ test/testing/ test/tracing/ test/tools/ test/human_in_the_loop test/evaluation test/document_stores test/dataclasses test/utils/ test/components/embedders/}"
 
 [tool.hatch.envs.e2e]
 template = "test"
diff --git a/test/components/embedders/image/test_sentence_transformers_doc_image_embedder.py b/test/components/embedders/image/test_sentence_transformers_doc_image_embedder.py
index 587df63eabd..990f1b0ff3f 100644
--- a/test/components/embedders/image/test_sentence_transformers_doc_image_embedder.py
+++ b/test/components/embedders/image/test_sentence_transformers_doc_image_embedder.py
@@ -229,12 +229,12 @@ def test_run_wrong_input_format(self):
         with pytest.raises(
             TypeError, match="SentenceTransformersDocumentImageEmbedder expects a list of Documents as input"
         ):
-            embedder.run(documents=string_input)
+            embedder.run(documents=string_input)  # type: ignore[arg-type]
 
         with pytest.raises(
             TypeError, match="SentenceTransformersDocumentImageEmbedder expects a list of Documents as input"
         ):
-            embedder.run(documents=list_integers_input)
+            embedder.run(documents=list_integers_input)  # type: ignore[arg-type]
 
     @patch(f"{IMPORT_PATH}._SentenceTransformersEmbeddingBackendFactory")
     def test_model_onnx_backend(self, mocked_factory):
diff --git a/test/components/embedders/test_hugging_face_api_document_embedder.py b/test/components/embedders/test_hugging_face_api_document_embedder.py
index 477123ae512..243a68a36d0 100644
--- a/test/components/embedders/test_hugging_face_api_document_embedder.py
+++ b/test/components/embedders/test_hugging_face_api_document_embedder.py
@@ -271,7 +271,7 @@ def test_run_wrong_input_format(self, mock_check_valid_model):
         list_integers_input = [1, 2, 3]
 
         with pytest.raises(TypeError):
-            embedder.run(text=list_integers_input)
+            embedder.run(text=list_integers_input)  # type: ignore[call-arg]
 
     def test_run_on_empty_list(self, mock_check_valid_model):
         embedder = HuggingFaceAPIDocumentEmbedder(
@@ -280,7 +280,7 @@ def test_run_on_empty_list(self, mock_check_valid_model):
             token=Secret.from_token("fake-api-token"),
         )
 
-        empty_list_input = []
+        empty_list_input: list[Document] = []
         result = embedder.run(documents=empty_list_input)
 
         assert result["documents"] is not None
@@ -511,7 +511,7 @@ async def test_run_async_wrong_input_format(self, mock_check_valid_model):
         list_integers_input = [1, 2, 3]
 
         with pytest.raises(TypeError):
-            await embedder.run_async(text=list_integers_input)
+            await embedder.run_async(text=list_integers_input)  # type: ignore[call-arg]
 
     @pytest.mark.asyncio
     async def test_run_async_on_empty_list(self, mock_check_valid_model):
@@ -521,7 +521,7 @@ async def test_run_async_on_empty_list(self, mock_check_valid_model):
             token=Secret.from_token("fake-api-token"),
         )
 
-        empty_list_input = []
+        empty_list_input: list[Document] = []
         result = await embedder.run_async(documents=empty_list_input)
 
         assert result["documents"] is not None
diff --git a/test/components/embedders/test_hugging_face_api_text_embedder.py b/test/components/embedders/test_hugging_face_api_text_embedder.py
index 53e0d414068..0c6e53d8a7a 100644
--- a/test/components/embedders/test_hugging_face_api_text_embedder.py
+++ b/test/components/embedders/test_hugging_face_api_text_embedder.py
@@ -137,7 +137,7 @@ def test_run_wrong_input_format(self, mock_check_valid_model):
         list_integers_input = [1, 2, 3]
 
         with pytest.raises(TypeError):
-            embedder.run(text=list_integers_input)
+            embedder.run(text=list_integers_input)  # type: ignore[arg-type]
 
     def test_run(self, mock_check_valid_model, caplog):
         with patch("huggingface_hub.InferenceClient.feature_extraction") as mock_embedding_patch:
diff --git a/test/components/embedders/test_openai_document_embedder.py b/test/components/embedders/test_openai_document_embedder.py
index 4a97e7c457a..c9588e96986 100644
--- a/test/components/embedders/test_openai_document_embedder.py
+++ b/test/components/embedders/test_openai_document_embedder.py
@@ -198,15 +198,15 @@ def test_run_wrong_input_format(self):
         list_integers_input = [1, 2, 3]
 
         with pytest.raises(TypeError, match="OpenAIDocumentEmbedder expects a list of Documents as input"):
-            embedder.run(documents=string_input)
+            embedder.run(documents=string_input)  # type: ignore[arg-type]
 
         with pytest.raises(TypeError, match="OpenAIDocumentEmbedder expects a list of Documents as input"):
-            embedder.run(documents=list_integers_input)
+            embedder.run(documents=list_integers_input)  # type: ignore[arg-type]
 
     def test_run_on_empty_list(self):
         embedder = OpenAIDocumentEmbedder(api_key=Secret.from_token("fake-api-key"))
 
-        empty_list_input = []
+        empty_list_input: list[Document] = []
         result = embedder.run(documents=empty_list_input)
 
         assert result["documents"] is not None
diff --git a/test/components/embedders/test_openai_text_embedder.py b/test/components/embedders/test_openai_text_embedder.py
index 4b386fc6a71..dab26a13a26 100644
--- a/test/components/embedders/test_openai_text_embedder.py
+++ b/test/components/embedders/test_openai_text_embedder.py
@@ -7,6 +7,7 @@
 
 import pytest
 from openai.types import CreateEmbeddingResponse, Embedding
+from openai.types.create_embedding_response import Usage
 
 from haystack.components.embedders.openai_text_embedder import OpenAITextEmbedder
 from haystack.utils.auth import Secret
@@ -166,7 +167,7 @@ def test_prepare_output(self, monkeypatch):
             data=[Embedding(embedding=[0.1, 0.2, 0.3], index=0, object="embedding")],
             model="text-embedding-ada-002",
             object="list",
-            usage={"prompt_tokens": 6, "total_tokens": 6},
+            usage=Usage(prompt_tokens=6, total_tokens=6),
         )
 
         embedder = OpenAITextEmbedder()
@@ -182,7 +183,7 @@ def test_run_wrong_input_format(self):
         list_integers_input = [1, 2, 3]
 
         with pytest.raises(TypeError, match="OpenAITextEmbedder expects a string as an input"):
-            embedder.run(text=list_integers_input)
+            embedder.run(text=list_integers_input)  # type: ignore[arg-type]
 
     @pytest.mark.skipif(os.environ.get("OPENAI_API_KEY", "") == "", reason="OPENAI_API_KEY is not set")
     @pytest.mark.integration
diff --git a/test/components/embedders/test_sentence_transformers_document_embedder.py b/test/components/embedders/test_sentence_transformers_document_embedder.py
index 3ce07c8dc72..c584fb508dc 100644
--- a/test/components/embedders/test_sentence_transformers_document_embedder.py
+++ b/test/components/embedders/test_sentence_transformers_document_embedder.py
@@ -265,6 +265,7 @@ def test_warmup(self, mocked_factory):
         )
         mocked_factory.get_embedding_backend.assert_not_called()
         embedder.warm_up()
+        assert embedder.embedding_backend is not None
         embedder.embedding_backend.model.max_seq_length = 512
         mocked_factory.get_embedding_backend.assert_called_once_with(
             model="model",
@@ -317,12 +318,12 @@ def test_run_wrong_input_format(self):
         with pytest.raises(
             TypeError, match="SentenceTransformersDocumentEmbedder expects a list of Documents as input"
         ):
-            embedder.run(documents=string_input)
+            embedder.run(documents=string_input)  # type: ignore[arg-type]
 
         with pytest.raises(
             TypeError, match="SentenceTransformersDocumentEmbedder expects a list of Documents as input"
         ):
-            embedder.run(documents=list_integers_input)
+            embedder.run(documents=list_integers_input)  # type: ignore[arg-type]
 
     def test_embed_metadata(self):
         embedder = SentenceTransformersDocumentEmbedder(
diff --git a/test/components/embedders/test_sentence_transformers_sparse_document_embedder.py b/test/components/embedders/test_sentence_transformers_sparse_document_embedder.py
index 193be682a4a..b4967fa1caf 100644
--- a/test/components/embedders/test_sentence_transformers_sparse_document_embedder.py
+++ b/test/components/embedders/test_sentence_transformers_sparse_document_embedder.py
@@ -225,6 +225,7 @@ def test_warmup(self, mocked_factory):
         )
         mocked_factory.get_embedding_backend.assert_not_called()
         embedder.warm_up()
+        assert embedder.embedding_backend is not None
         embedder.embedding_backend.model.max_seq_length = 512
         mocked_factory.get_embedding_backend.assert_called_once_with(
             model="model",
@@ -279,12 +280,12 @@ def test_run_wrong_input_format(self):
         with pytest.raises(
             TypeError, match="SentenceTransformersSparseDocumentEmbedder expects a list of Documents as input"
         ):
-            embedder.run(documents=string_input)
+            embedder.run(documents=string_input)  # type: ignore[arg-type]
 
         with pytest.raises(
             TypeError, match="SentenceTransformersSparseDocumentEmbedder expects a list of Documents as input"
         ):
-            embedder.run(documents=list_integers_input)
+            embedder.run(documents=list_integers_input)  # type: ignore[arg-type]
 
     def test_embed_metadata(self):
         embedder = SentenceTransformersSparseDocumentEmbedder(
diff --git a/test/components/embedders/test_sentence_transformers_sparse_text_embedder.py b/test/components/embedders/test_sentence_transformers_sparse_text_embedder.py
index 72c806dc29f..146b9ac2f39 100644
--- a/test/components/embedders/test_sentence_transformers_sparse_text_embedder.py
+++ b/test/components/embedders/test_sentence_transformers_sparse_text_embedder.py
@@ -234,7 +234,7 @@ def test_run_wrong_input_format(self):
         list_integers_input = [1, 2, 3]
 
         with pytest.raises(TypeError, match="SentenceTransformersSparseTextEmbedder expects a string as input"):
-            embedder.run(text=list_integers_input)
+            embedder.run(text=list_integers_input)  # type: ignore[arg-type]
 
     @patch(
         "haystack.components.embedders.sentence_transformers_sparse_text_embedder._SentenceTransformersSparseEmbeddingBackendFactory"
diff --git a/test/components/embedders/test_sentence_transformers_text_embedder.py b/test/components/embedders/test_sentence_transformers_text_embedder.py
index 16131f30561..7fe7de21eb1 100644
--- a/test/components/embedders/test_sentence_transformers_text_embedder.py
+++ b/test/components/embedders/test_sentence_transformers_text_embedder.py
@@ -240,6 +240,7 @@ def test_warmup(self, mocked_factory):
         )
         mocked_factory.get_embedding_backend.assert_not_called()
         embedder.warm_up()
+        assert embedder.embedding_backend is not None
         embedder.embedding_backend.model.max_seq_length = 512
         mocked_factory.get_embedding_backend.assert_called_once_with(
             model="model",
@@ -285,7 +286,7 @@ def test_run_wrong_input_format(self):
         list_integers_input = [1, 2, 3]
 
         with pytest.raises(TypeError, match="SentenceTransformersTextEmbedder expects a string as input"):
-            embedder.run(text=list_integers_input)
+            embedder.run(text=list_integers_input)  # type: ignore[arg-type]
 
     def test_embed_encode_kwargs(self):
         embedder = SentenceTransformersTextEmbedder(model="model", encode_kwargs={"task": "retrieval.query"})

From 28a2a0a30fe4ce86630587b1a23e97f605f1cb1a Mon Sep 17 00:00:00 2001
From: bogdankostic <bogdankostic@web.de>
Date: Thu, 9 Jul 2026 10:58:15 +0200
Subject: [PATCH 2/4] remove redundant embedder test files

---
 .../embedders/test_hugging_face_api_document_embedder.py          | 0
 test/components/embedders/test_hugging_face_api_text_embedder.py  | 0
 .../embedders/test_sentence_transformers_document_embedder.py     | 0
 .../test_sentence_transformers_sparse_document_embedder.py        | 0
 .../embedders/test_sentence_transformers_sparse_text_embedder.py  | 0
 .../embedders/test_sentence_transformers_text_embedder.py         | 0
 6 files changed, 0 insertions(+), 0 deletions(-)
 delete mode 100644 test/components/embedders/test_hugging_face_api_document_embedder.py
 delete mode 100644 test/components/embedders/test_hugging_face_api_text_embedder.py
 delete mode 100644 test/components/embedders/test_sentence_transformers_document_embedder.py
 delete mode 100644 test/components/embedders/test_sentence_transformers_sparse_document_embedder.py
 delete mode 100644 test/components/embedders/test_sentence_transformers_sparse_text_embedder.py
 delete mode 100644 test/components/embedders/test_sentence_transformers_text_embedder.py

diff --git a/test/components/embedders/test_hugging_face_api_document_embedder.py b/test/components/embedders/test_hugging_face_api_document_embedder.py
deleted file mode 100644
index e69de29bb2d..00000000000
diff --git a/test/components/embedders/test_hugging_face_api_text_embedder.py b/test/components/embedders/test_hugging_face_api_text_embedder.py
deleted file mode 100644
index e69de29bb2d..00000000000
diff --git a/test/components/embedders/test_sentence_transformers_document_embedder.py b/test/components/embedders/test_sentence_transformers_document_embedder.py
deleted file mode 100644
index e69de29bb2d..00000000000
diff --git a/test/components/embedders/test_sentence_transformers_sparse_document_embedder.py b/test/components/embedders/test_sentence_transformers_sparse_document_embedder.py
deleted file mode 100644
index e69de29bb2d..00000000000
diff --git a/test/components/embedders/test_sentence_transformers_sparse_text_embedder.py b/test/components/embedders/test_sentence_transformers_sparse_text_embedder.py
deleted file mode 100644
index e69de29bb2d..00000000000
diff --git a/test/components/embedders/test_sentence_transformers_text_embedder.py b/test/components/embedders/test_sentence_transformers_text_embedder.py
deleted file mode 100644
index e69de29bb2d..00000000000

From 9265134a603ae991fe2514a5107190eebd1b8348 Mon Sep 17 00:00:00 2001
From: bogdankostic <bogdankostic@web.de>
Date: Thu, 9 Jul 2026 10:59:04 +0200
Subject: [PATCH 3/4] remove test_sentence_transformers_doc_image_embedder.py

---
 .../image/test_sentence_transformers_doc_image_embedder.py        | 0
 1 file changed, 0 insertions(+), 0 deletions(-)
 delete mode 100644 test/components/embedders/image/test_sentence_transformers_doc_image_embedder.py

diff --git a/test/components/embedders/image/test_sentence_transformers_doc_image_embedder.py b/test/components/embedders/image/test_sentence_transformers_doc_image_embedder.py
deleted file mode 100644
index e69de29bb2d..00000000000

From 04b196fda3055fa7250ea7040a54ccdff2a1228d Mon Sep 17 00:00:00 2001
From: bogdankostic <bogdankostic@web.de>
Date: Thu, 9 Jul 2026 11:54:07 +0200
Subject: [PATCH 4/4] add assertions for client initialization across embedder
 tests

---
 .../embedders/test_azure_document_embedder.py        | 11 +++++++++--
 .../components/embedders/test_azure_text_embedder.py |  9 +++++++--
 test/components/embedders/test_mock_text_embedder.py |  6 ++++--
 .../embedders/test_openai_document_embedder.py       | 12 ++++++++++--
 .../embedders/test_openai_text_embedder.py           |  9 +++++++--
 5 files changed, 37 insertions(+), 10 deletions(-)

diff --git a/test/components/embedders/test_azure_document_embedder.py b/test/components/embedders/test_azure_document_embedder.py
index e38866fbd80..12cbe6b7b86 100644
--- a/test/components/embedders/test_azure_document_embedder.py
+++ b/test/components/embedders/test_azure_document_embedder.py
@@ -216,6 +216,7 @@ def test_embed_batch_handles_exceptions_gracefully(self, caplog):
             embedding_separator=" | ",
         )
         embedder.warm_up()
+        assert embedder.client is not None
 
         fake_texts_to_embed = {"1": "text1", "2": "text2"}
 
@@ -237,6 +238,7 @@ def test_embed_batch_raises_exception_on_failure(self):
             raise_on_failure=True,
         )
         embedder.warm_up()
+        assert embedder.client is not None
         fake_texts_to_embed = {"1": "text1", "2": "text2"}
         with patch.object(
             embedder.client.embeddings,
@@ -303,6 +305,7 @@ def test_warm_up_uses_default_timeout_and_max_retries(self, monkeypatch):
         monkeypatch.setenv("AZURE_OPENAI_API_KEY", "fake-api-key")
         embedder = AzureOpenAIDocumentEmbedder(azure_endpoint="https://example-resource.azure.openai.com/")
         embedder.warm_up()
+        assert embedder.client is not None
         assert embedder.client.max_retries == 5
         assert embedder.client.timeout == 30.0
 
@@ -312,6 +315,7 @@ def test_warm_up_uses_timeout_and_max_retries_from_parameters(self, monkeypatch)
             azure_endpoint="https://example-resource.azure.openai.com/", timeout=40.0, max_retries=1
         )
         embedder.warm_up()
+        assert embedder.client is not None
         assert embedder.client.max_retries == 1
         assert embedder.client.timeout == 40.0
 
@@ -321,6 +325,7 @@ def test_warm_up_uses_timeout_and_max_retries_from_env_vars(self, monkeypatch):
         monkeypatch.setenv("OPENAI_MAX_RETRIES", "10")
         embedder = AzureOpenAIDocumentEmbedder(azure_endpoint="https://example-resource.azure.openai.com/")
         embedder.warm_up()
+        assert embedder.client is not None
         assert embedder.client.max_retries == 10
         assert embedder.client.timeout == 100.0
 
@@ -334,6 +339,7 @@ def test_key_resolved_at_warm_up_not_init(self, monkeypatch):
 
     def test_sync_lifecycle(self, mock_azure_clients):
         sync_cls, _ = mock_azure_clients
+        sync_client = sync_cls.return_value
         embedder = AzureOpenAIDocumentEmbedder(azure_endpoint="https://example-resource.azure.openai.com/")
         assert embedder.client is None
         assert embedder.async_client is None
@@ -343,11 +349,12 @@ def test_sync_lifecycle(self, mock_azure_clients):
         assert embedder.async_client is None
 
         embedder.close()
-        sync_cls.return_value.close.assert_called_once()
+        sync_client.close.assert_called_once()
         assert embedder.client is None
 
     async def test_async_lifecycle(self, mock_azure_clients):
         _, async_cls = mock_azure_clients
+        async_client = async_cls.return_value
         embedder = AzureOpenAIDocumentEmbedder(azure_endpoint="https://example-resource.azure.openai.com/")
 
         await embedder.warm_up_async()
@@ -355,7 +362,7 @@ async def test_async_lifecycle(self, mock_azure_clients):
         assert embedder.client is None
 
         await embedder.close_async()
-        async_cls.return_value.close.assert_awaited_once()
+        async_client.close.assert_awaited_once()
         assert embedder.async_client is None
 
     async def test_close_is_safe_without_warm_up(self, mock_azure_clients):
diff --git a/test/components/embedders/test_azure_text_embedder.py b/test/components/embedders/test_azure_text_embedder.py
index a1a1f2ebc90..b71c2913db3 100644
--- a/test/components/embedders/test_azure_text_embedder.py
+++ b/test/components/embedders/test_azure_text_embedder.py
@@ -216,6 +216,7 @@ def test_warm_up_uses_default_timeout_and_max_retries(self, monkeypatch):
         monkeypatch.setenv("AZURE_OPENAI_API_KEY", "fake-api-key")
         embedder = AzureOpenAITextEmbedder(azure_endpoint="https://example-resource.azure.openai.com/")
         embedder.warm_up()
+        assert embedder.client is not None
         assert embedder.client.max_retries == 5
         assert embedder.client.timeout == 30.0
 
@@ -225,6 +226,7 @@ def test_warm_up_uses_timeout_and_max_retries_from_parameters(self, monkeypatch)
             azure_endpoint="https://example-resource.azure.openai.com/", timeout=40.0, max_retries=1
         )
         embedder.warm_up()
+        assert embedder.client is not None
         assert embedder.client.max_retries == 1
         assert embedder.client.timeout == 40.0
 
@@ -234,6 +236,7 @@ def test_warm_up_uses_timeout_and_max_retries_from_env_vars(self, monkeypatch):
         monkeypatch.setenv("OPENAI_MAX_RETRIES", "10")
         embedder = AzureOpenAITextEmbedder(azure_endpoint="https://example-resource.azure.openai.com/")
         embedder.warm_up()
+        assert embedder.client is not None
         assert embedder.client.max_retries == 10
         assert embedder.client.timeout == 100.0
 
@@ -247,6 +250,7 @@ def test_key_resolved_at_warm_up_not_init(self, monkeypatch):
 
     def test_sync_lifecycle(self, mock_azure_clients):
         sync_cls, _ = mock_azure_clients
+        sync_client = sync_cls.return_value
         embedder = AzureOpenAITextEmbedder(azure_endpoint="https://example-resource.azure.openai.com/")
         assert embedder.client is None
         assert embedder.async_client is None
@@ -256,11 +260,12 @@ def test_sync_lifecycle(self, mock_azure_clients):
         assert embedder.async_client is None
 
         embedder.close()
-        sync_cls.return_value.close.assert_called_once()
+        sync_client.close.assert_called_once()
         assert embedder.client is None
 
     async def test_async_lifecycle(self, mock_azure_clients):
         _, async_cls = mock_azure_clients
+        async_client = async_cls.return_value
         embedder = AzureOpenAITextEmbedder(azure_endpoint="https://example-resource.azure.openai.com/")
 
         await embedder.warm_up_async()
@@ -268,7 +273,7 @@ async def test_async_lifecycle(self, mock_azure_clients):
         assert embedder.client is None
 
         await embedder.close_async()
-        async_cls.return_value.close.assert_awaited_once()
+        async_client.close.assert_awaited_once()
         assert embedder.async_client is None
 
     async def test_close_is_safe_without_warm_up(self, mock_azure_clients):
diff --git a/test/components/embedders/test_mock_text_embedder.py b/test/components/embedders/test_mock_text_embedder.py
index 05103e1d927..2649edffa9d 100644
--- a/test/components/embedders/test_mock_text_embedder.py
+++ b/test/components/embedders/test_mock_text_embedder.py
@@ -60,7 +60,8 @@ def test_embedding_fn(self):
         assert MockTextEmbedder(embedding_fn=_ones).run("hello")["embedding"] == [1.0, 1.0, 1.0]
 
     def test_embedding_fn_invalid_return_raises(self):
-        embedder = MockTextEmbedder(embedding_fn=lambda text: "not a vector")
+        # embedding_fn deliberately returns a non-vector to exercise the runtime type check
+        embedder = MockTextEmbedder(embedding_fn=lambda text: "not a vector")  # type: ignore[arg-type, return-value]
         with pytest.raises(TypeError, match="must be a sequence of numbers"):
             embedder.run("hello")
 
@@ -79,8 +80,9 @@ def test_meta(self):
         assert custom["extra"] == "value"
 
     def test_run_rejects_non_string(self):
+        # a non-string input is passed on purpose to exercise the runtime type check
         with pytest.raises(TypeError, match="expects a string"):
-            MockTextEmbedder().run(["not", "a", "string"])
+            MockTextEmbedder().run(["not", "a", "string"])  # type: ignore[arg-type]
 
     async def test_run_async(self):
         embedder = MockTextEmbedder(dimension=8)
diff --git a/test/components/embedders/test_openai_document_embedder.py b/test/components/embedders/test_openai_document_embedder.py
index ed315db540b..84cb5753e88 100644
--- a/test/components/embedders/test_openai_document_embedder.py
+++ b/test/components/embedders/test_openai_document_embedder.py
@@ -217,6 +217,7 @@ def test_run_on_empty_list(self):
     def test_embed_batch_handles_exceptions_gracefully(self, caplog):
         embedder = OpenAIDocumentEmbedder(api_key=Secret.from_token("fake_api_key"))
         embedder.warm_up()
+        assert embedder.client is not None
         fake_texts_to_embed = {"1": "text1", "2": "text2"}
         with patch.object(
             embedder.client.embeddings,
@@ -231,6 +232,7 @@ def test_embed_batch_handles_exceptions_gracefully(self, caplog):
     def test_run_handles_exceptions_gracefully(self, caplog):
         embedder = OpenAIDocumentEmbedder(api_key=Secret.from_token("fake_api_key"), batch_size=1)
         embedder.warm_up()
+        assert embedder.client is not None
         docs = [
             Document(content="I love cheese", meta={"topic": "Cuisine"}),
             Document(content="A transformer is a deep learning architecture", meta={"topic": "ML"}),
@@ -260,6 +262,7 @@ def test_run_handles_exceptions_gracefully(self, caplog):
     def test_embed_batch_raises_exception_on_failure(self):
         embedder = OpenAIDocumentEmbedder(api_key=Secret.from_token("fake_api_key"), raise_on_failure=True)
         embedder.warm_up()
+        assert embedder.client is not None
         fake_texts_to_embed = {"1": "text1", "2": "text2"}
         with patch.object(
             embedder.client.embeddings,
@@ -354,12 +357,14 @@ def test_warm_up_uses_default_timeout_and_max_retries(self, monkeypatch):
         monkeypatch.setenv("OPENAI_API_KEY", "fake-api-key")
         embedder = OpenAIDocumentEmbedder()
         embedder.warm_up()
+        assert embedder.client is not None
         assert embedder.client.max_retries == 5
         assert embedder.client.timeout == 30.0
 
     def test_warm_up_uses_timeout_and_max_retries_from_parameters(self):
         embedder = OpenAIDocumentEmbedder(api_key=Secret.from_token("fake-api-key"), timeout=40.0, max_retries=1)
         embedder.warm_up()
+        assert embedder.client is not None
         assert embedder.client.max_retries == 1
         assert embedder.client.timeout == 40.0
 
@@ -368,6 +373,7 @@ def test_warm_up_uses_timeout_and_max_retries_from_env_vars(self, monkeypatch):
         monkeypatch.setenv("OPENAI_MAX_RETRIES", "10")
         embedder = OpenAIDocumentEmbedder(api_key=Secret.from_token("fake-api-key"))
         embedder.warm_up()
+        assert embedder.client is not None
         assert embedder.client.max_retries == 10
         assert embedder.client.timeout == 100.0
 
@@ -379,6 +385,7 @@ def test_key_resolved_at_warm_up_not_init(self, monkeypatch):
 
     def test_sync_lifecycle(self, mock_openai_clients):
         sync_cls, _ = mock_openai_clients
+        sync_client = sync_cls.return_value
         embedder = OpenAIDocumentEmbedder()
         assert embedder.client is None
         assert embedder.async_client is None
@@ -388,11 +395,12 @@ def test_sync_lifecycle(self, mock_openai_clients):
         assert embedder.async_client is None
 
         embedder.close()
-        sync_cls.return_value.close.assert_called_once()
+        sync_client.close.assert_called_once()
         assert embedder.client is None
 
     async def test_async_lifecycle(self, mock_openai_clients):
         _, async_cls = mock_openai_clients
+        async_client = async_cls.return_value
         embedder = OpenAIDocumentEmbedder()
 
         await embedder.warm_up_async()
@@ -400,7 +408,7 @@ async def test_async_lifecycle(self, mock_openai_clients):
         assert embedder.client is None
 
         await embedder.close_async()
-        async_cls.return_value.close.assert_awaited_once()
+        async_client.close.assert_awaited_once()
         assert embedder.async_client is None
 
     async def test_close_is_safe_without_warm_up(self, mock_openai_clients):
diff --git a/test/components/embedders/test_openai_text_embedder.py b/test/components/embedders/test_openai_text_embedder.py
index 3c94b88643e..d9283434b17 100644
--- a/test/components/embedders/test_openai_text_embedder.py
+++ b/test/components/embedders/test_openai_text_embedder.py
@@ -242,12 +242,14 @@ def test_warm_up_uses_default_timeout_and_max_retries(self, monkeypatch):
         monkeypatch.setenv("OPENAI_API_KEY", "fake-api-key")
         embedder = OpenAITextEmbedder()
         embedder.warm_up()
+        assert embedder.client is not None
         assert embedder.client.max_retries == 5
         assert embedder.client.timeout == 30.0
 
     def test_warm_up_uses_timeout_and_max_retries_from_parameters(self):
         embedder = OpenAITextEmbedder(api_key=Secret.from_token("fake-api-key"), timeout=40.0, max_retries=1)
         embedder.warm_up()
+        assert embedder.client is not None
         assert embedder.client.max_retries == 1
         assert embedder.client.timeout == 40.0
 
@@ -256,6 +258,7 @@ def test_warm_up_uses_timeout_and_max_retries_from_env_vars(self, monkeypatch):
         monkeypatch.setenv("OPENAI_MAX_RETRIES", "10")
         embedder = OpenAITextEmbedder(api_key=Secret.from_token("fake-api-key"))
         embedder.warm_up()
+        assert embedder.client is not None
         assert embedder.client.max_retries == 10
         assert embedder.client.timeout == 100.0
 
@@ -267,6 +270,7 @@ def test_key_resolved_at_warm_up_not_init(self, monkeypatch):
 
     def test_sync_lifecycle(self, mock_openai_clients):
         sync_cls, _ = mock_openai_clients
+        sync_client = sync_cls.return_value
         embedder = OpenAITextEmbedder()
         assert embedder.client is None
         assert embedder.async_client is None
@@ -276,11 +280,12 @@ def test_sync_lifecycle(self, mock_openai_clients):
         assert embedder.async_client is None
 
         embedder.close()
-        sync_cls.return_value.close.assert_called_once()
+        sync_client.close.assert_called_once()
         assert embedder.client is None
 
     async def test_async_lifecycle(self, mock_openai_clients):
         _, async_cls = mock_openai_clients
+        async_client = async_cls.return_value
         embedder = OpenAITextEmbedder()
 
         await embedder.warm_up_async()
@@ -288,7 +293,7 @@ async def test_async_lifecycle(self, mock_openai_clients):
         assert embedder.client is None
 
         await embedder.close_async()
-        async_cls.return_value.close.assert_awaited_once()
+        async_client.close.assert_awaited_once()
         assert embedder.async_client is None
 
     async def test_close_is_safe_without_warm_up(self, mock_openai_clients):