Allow chaining noprocess fixtures - closes #890

[fizyk]

This allows for more complex test suites with common base data fixture
Extended for a specific group of tests that needs additional data elements in database

Chore that needs to be done:

• Add newsfragment pipenv run towncrier create [issue_number].[type].rst

Types are defined in the pyproject.toml, issue_number either from issue tracker or the Pull request number

Summary by CodeRabbit

• New Features

  • Added a depends_on parameter to enable hierarchical fixture chaining for layered database pre-population.

• Documentation

  • Added "Chaining fixtures" guidance, examples and an architecture diagram illustrating multi‑layer fixture cloning.

• Tests

  • Added tests covering two‑ and three‑layer chaining, data propagation and inheritance of connection parameters.

• Breaking Changes

  • Database janitor/template handling updated to explicit template management with an as_template flag.

• Chores

  • Minimum pytest requirement bumped to 8.2.

_{✏️ Tip: You can customize this high-level summary in your review settings.}

[coderabbitai]

Walkthrough

Adds fixture chaining for postgresql_noproc via a new depends_on parameter, refactors DatabaseJanitor to require explicit dbname and an as_template flag, updates process integration and tests, adds docs (Mermaid diagram) and release fragments, and bumps the pytest minimum to >= 8.2.

Changes

Cohort / File(s)	Summary
Core fixture chaining implementation pytest_postgresql/factories/noprocess.py	Adds depends_on parameter to postgresql_noproc, resolve connection params from the dependent fixture when set, derive base template DB name, adjust NoopExecutor db naming and fixture signature, and update docstrings.
Database janitor refactor pytest_postgresql/janitor.py	Makes dbname required, adds as_template: bool, centralises create/load/drop to use self.dbname, and changes template marking/unmarking logic.
Process fixture integration pytest_postgresql/factories/process.py	Updates DatabaseJanitor construction to dbname=... with as_template=True for template janitors (replacing prior template_dbname=...).
Tests: chaining & adjustments tests/test_chaining.py, tests/test_postgres_options_plugin.py, tests/test_postgresql.py	Adds tests/test_chaining.py for multi-layer fixture tests; updates tests to the new DatabaseJanitor signature/attributes; replaces a version-based skip with an xdist group.
Documentation README.rst, docs/architecture_chaining.mmd	Adds "Chaining fixtures" section and example to README and a Mermaid diagram file illustrating layered fixture orchestration.
Release notes newsfragments/890.break.rst, newsfragments/890.docs.rst, newsfragments/890.feature.rst, newsfragments/890.break.1.rst	Adds fragments documenting the janitor breaking change, the new depends_on feature, the Mermaid diagram, and the pytest minimum bump.
Packaging / CI pyproject.toml, oldest/requirements.txt	Bumps pytest minimum to >= 8.2 and pins pytest in oldest requirements (pytest == 8.2).

Sequence Diagram

sequenceDiagram
    participant Test
    participant ProcF as BaseProc (proc fixture)
    participant Noop1 as SeededNoop (noproc fixture)
    participant Noop2 as MoreSeededNoop (noproc fixture)
    participant DB as PostgreSQL Database

    Test->>ProcF: request `base_proc`
    ProcF->>DB: create base_db, load schema
    ProcF-->>Test: return PostgreSQLExecutor (template dbname)

    Test->>Noop1: request `seeded_noproc` (depends_on=`base_proc`)
    Noop1->>ProcF: read connection & template info
    Noop1->>DB: create seeded_db USING TEMPLATE base_db, load data
    Noop1-->>Test: return NoopExecutor (seeded_db)

    Test->>Noop2: request `more_seeded_noproc` (depends_on=`seeded_noproc`)
    Noop2->>Noop1: read connection & template info
    Noop2->>DB: create more_seeded_db USING TEMPLATE seeded_db, load more data
    Noop2-->>Test: return NoopExecutor (more_seeded_db)

    Test->>DB: validate tables and data across layers
    Test-->>Test: assertions

Loading

Estimated code review effort

🎯 4 (Complex) | ⏱️ ~60 minutes

Poem

🐇 I layered databases, one by one,

A base, then seeds beneath the sun,
The janitor marks doors open wide,
Fixtures hop and clone with pride—
Hooray for chaining; carrots: well done!

🚥 Pre-merge checks | ✅ 3

✅ Passed checks (3 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title clearly and concisely describes the main feature addition: enabling chaining of noprocess fixtures, and references the closed issue number for context.
Docstring Coverage	✅ Passed	Docstring coverage is 95.24% which is sufficient. The required threshold is 80.00%.

_{✏️ Tip: You can configure your own custom pre-merge checks in the settings.}

✨ Finishing touches

• 📝 Generate docstrings

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[fizyk]

@coderabbitai review

[coderabbitai]

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[coderabbitai]

Actionable comments posted: 1

🤖 Fix all issues with AI agents

In `@pytest_postgresql/factories/noprocess.py`:
- Line 79: The pg_options local is being overwritten unconditionally after the
depends_on/else branches; remove the duplicate assignment so that pg_options
retains the value set in the depends_on branch (base.options) or the else branch
instead of always becoming config.options. Locate the code that assigns
pg_options in the factory function (the assignments at the depends_on branch
that set base.options, the else branch, and the later line `pg_options = options
or config.options`) and delete the later unconditional `pg_options = options or
config.options` so pg_options is only set by the intended branch logic.

🧹 Nitpick comments (1)

tests/test_chaining.py (1)

96-101: Consider adding assertion for options inheritance.

This test validates that host, port, user, and password are inherited, but does not verify options. Given the pg_options overwrite bug identified in noprocess.py, adding an assertion for options would help catch such regressions.

♻️ Suggested addition

     assert seeded_noproc.host == base_proc.host
     assert seeded_noproc.port == base_proc.port
     assert seeded_noproc.user == base_proc.user
     assert seeded_noproc.password == base_proc.password
+    assert seeded_noproc.options == base_proc.options

[coderabbitai]

Actionable comments posted: 1

🤖 Fix all issues with AI agents

In @.github/workflows/oldest-postgres.yml:
- Line 68: The pytest invocation in the workflow's `command:` duplicates
verbosity flags already present in `pyproject.oldest.toml`; remove `-vv
--setup-show` from the `command:` string so the command becomes `pytest -n auto
-c pyproject.oldest.toml --dist loadgroup --max-worker-restart 0
--postgresql-exec="/usr/lib/postgresql/${{ inputs.postgresql }}/bin/pg_ctl" -k
"not docker" --cov-report=xml:coverage-xdist.xml`, leaving `addopts` in
`pyproject.oldest.toml` to control verbosity.

[coderabbitai]

Actionable comments posted: 1

🤖 Fix all issues with AI agents

In `@newsfragments/890.break.1.rst`:
- Around line 3-5: Fix the grammatical issues in the news fragment: change the
phrase "version behave flaky" to "versions behave flakily" (plural subject +
adverb) and remove the redundant word so "fixture chaining fixture" becomes
"fixture chaining". Ensure the resulting sentence reads smoothly with "versions
behave flakily with getfixturefunction requests on Python 3.12-3.13 in fixture
chaining when used alongside xdist."

[coderabbitai]

Actionable comments posted: 1

🤖 Fix all issues with AI agents

In `@pyproject.toml`:
- Line 31: Add a breaking change newsfragment documenting the pytest bump
introduced in pyproject.toml: create a file in newsfragments/ (e.g.,
1XXXXX.break) that states pytest 8.2+ is now required, including why (what
changed) and migration notes for users; while adding the fragment, also verify
whether pytest 8.2 is truly necessary (inspect the change that prompted the bump
and any usage of features like fixture chaining from pytest-postgresql) and if a
lower pytest version suffices, update pyproject.toml accordingly and adjust the
newsfragment to reflect the accurate minimal required version.