New PyTest and migrated 3 other tests

[chiragpdesai77]

Hi Luigi, I created a new PyTest for test_asianoptions.py and migrated 3 others(test_blackformula_pytest, test_bondfunctions_pytest, test_bonds_pytest) from unittest to PyTest

Thank you

[Copilot]

Pull request overview

This PR introduces new pytest-based Python test modules for QuantLib-SWIG: it adds a new Asian options test suite and adds pytest equivalents for three existing unittest-based suites (Black formula, BondFunctions, Bonds).

Changes:

• Added a new pytest-style test_asianoptions.py covering multiple Asian option engines/cases.
• Added pytest versions of existing unittest suites: bonds, bond functions, and black formula.
• Introduced pytest fixtures for common setup/teardown in the migrated tests.

Reviewed changes

Copilot reviewed 4 out of 4 changed files in this pull request and generated 6 comments.

File	Description
Python/test/test_bonds_pytest.py	Pytest migration of the Bonds unittest suite using fixtures.
Python/test/test_bondfunctions_pytest.py	Pytest migration of the BondFunctions unittest suite using a fixture.
Python/test/test_blackformula_pytest.py	Pytest migration of the BlackFormula and BlackDeltaCalculator unittest suite.
Python/test/test_asianoptions.py	New pytest-based Asian options coverage across multiple engines and scenarios.

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[lballabio]

The conversion should edit the original tests, not add duplicates with a _pytest suffix.

In any case, note that porting tests from the C++ test suite to Python add very little value. The C++ tests already check that the library works, and SWIG is pretty reliable in exporting C++ code, so there's no need to check that again (unless we're adding specific features or syntax in the SWIG wrappers). I'd suggest putting effort elsewhere.