chore: avoid exporting components to the components package

[davidsbatista]

Proposed Changes:

Make the imports in test as specific as possible, to avoid importing/testing other components when locally testing a single component.

How did you test it?

• local unit tests,
• integration tests, manual verification
• CI tests

Checklist

• I have read the contributors guidelines and the code of conduct
• I have updated the related issue with new insights and changes
• I added unit tests and updated the docstrings
• I've used one of the conventional commit types for my PR title: fix:, feat:, build:, chore:, ci:, docs:, style:, refactor:, perf:, test:.
• I documented my code
• I ran pre-commit hooks and fixed any issue

[coveralls]

Pull Request Test Coverage Report for Build 12586724345

Details

• 0 of 0 changed or added relevant lines in 0 files are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage decreased (-0.07%) to 83.128%

---

Totals
Change from base Build 12575655783:	-0.07%
Covered Lines:	2025
Relevant Lines:	2436

---

💛 - Coveralls

[anakin87]

I have nothing against this PR, but it seems to do something different from what is described.

Currently, this works:
from haystack_experimental.components import LLMMetadataExtractor

After this PR, the above import won't work and you will need to do
from haystack_experimental.components.extractors import LLMMetadataExtractor

It would be helpful if you could explain the motivation behind this choice. (It does not seem related to tests).

[davidsbatista]

After this PR, the above import won't work and you will need to do
from haystack_experimental.components.extractors import LLMMetadataExtractor

check the file test/components/extractors/test_llm_metadata_extractor.py on the diff

[davidsbatista]

When I want to run the tests for a single local file, e..g:

13:25 $ coverage run --source haystack_experimental/components/retrievers/ -m pytest -vvv -s test/components/retrievers/test_auto_merging_retriever.py && coverage report --show-missing

This is what happens, due to the the way the import in the test file is done

==================================================================================================== test session starts ====================================================================================================
platform darwin -- Python 3.12.6, pytest-8.3.3, pluggy-1.5.0 -- /Users/dsbatista/haystack-experimental/.venv/bin/python3
cachedir: .pytest_cache
rootdir: /Users/dsbatista/haystack-experimental
configfile: pyproject.toml
plugins: cov-6.0.0, anyio-4.6.0, rerunfailures-14.0
collected 0 items / 1 error

========================================================================================================== ERRORS ===========================================================================================================
________________________________________________________________________ ERROR collecting test/components/retrievers/test_auto_merging_retriever.py _________________________________________________________________________
test/components/retrievers/test_auto_merging_retriever.py:5: in <module>
    from haystack_experimental.components.splitters import HierarchicalDocumentSplitter
haystack_experimental/components/__init__.py:5: in <module>
    from .extractors import LLMMetadataExtractor
haystack_experimental/components/extractors/__init__.py:5: in <module>
    from haystack_experimental.components.extractors.llm_metadata_extractor import LLMMetadataExtractor, LLMProvider
haystack_experimental/components/extractors/llm_metadata_extractor.py:26: in <module>
    from haystack_integrations.components.generators.google_vertex import VertexAIGeminiGenerator
.venv/lib/python3.12/site-packages/haystack_integrations/components/generators/google_vertex/__init__.py:4: in <module>
    from .captioner import VertexAIImageCaptioner
.venv/lib/python3.12/site-packages/haystack_integrations/components/generators/google_vertex/captioner.py:4: in <module>
    import vertexai
.venv/lib/python3.12/site-packages/vertexai/__init__.py:19: in <module>
    from google.cloud.aiplatform import version as aiplatform_version
.venv/lib/python3.12/site-packages/google/cloud/aiplatform/__init__.py:24: in <module>
    from google.cloud.aiplatform import initializer
.venv/lib/python3.12/site-packages/google/cloud/aiplatform/initializer.py:38: in <module>
    from google.cloud.aiplatform.metadata import metadata
.venv/lib/python3.12/site-packages/google/cloud/aiplatform/metadata/metadata.py:29: in <module>
    from google.cloud.aiplatform import pipeline_jobs
.venv/lib/python3.12/site-packages/google/cloud/aiplatform/pipeline_jobs.py:33: in <module>
    from google.cloud.aiplatform.metadata import artifact
.venv/lib/python3.12/site-packages/google/cloud/aiplatform/metadata/artifact.py:26: in <module>
    from google.cloud.aiplatform import models
.venv/lib/python3.12/site-packages/google/cloud/aiplatform/models.py:49: in <module>
    from google.cloud.aiplatform import jobs
.venv/lib/python3.12/site-packages/google/cloud/aiplatform/jobs.py:1736: in <module>
    class CustomJob(_RunnableJob, base.PreviewMixin):
.venv/lib/python3.12/site-packages/google/cloud/aiplatform/jobs.py:2237: in CustomJob
    scheduling_strategy: Optional[gca_custom_job_compat.Scheduling.DiversityRankingStrategy] = None,
E   AttributeError: type object 'Scheduling' has no attribute 'DiversityRankingStrategy'
===================================================================================================== warnings summary ======================================================================================================
.venv/lib/python3.12/site-packages/_pytest/config/__init__.py:1441
  /Users/dsbatista/haystack-experimental/.venv/lib/python3.12/site-packages/_pytest/config/__init__.py:1441: PytestConfigWarning: Unknown config option: asyncio_mode

    self._warn_or_fail_if_strict(f"Unknown config option: {key}\n")

-- Docs: https://docs.pytest.org/en/stable/how-to/capture-warnings.html
================================================================================================== short test summary info ==================================================================================================
ERROR test/components/retrievers/test_auto_merging_retriever.py - AttributeError: type object 'Scheduling' has no attribute 'DiversityRankingStrategy'
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! Interrupted: 1 error during collection !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
================================================================================================ 1 warning, 1 error in 4.37s ================================================================================================
/Users/dsbatista/haystack-experimental/.venv/lib/python3.12/site-packages/coverage/control.py:892: CoverageWarning: No data was collected. (no-data-collected)
  self._warn("No data was collected.", slug="no-data-collected")

I just want to test a single file and check it's coverage to understand where to focus on the tests, and due to the import it triggers unrelated tests

[anakin87]

Since the impact of this change extends beyond tests, I would suggest a more descriptive title.
Something like:
chore: avoid exporting components to the components package