Discovery miner: Python test functions (pytest, unittest)

[Dimwiddle]

Summary

Extract test functions from Python test files using tree-sitter. Produces DiscoveredItem(kind=TEST_FUNCTION) for each found test.

Depends on: #124, #125, #126

New file

src/specleft/discovery/miners/python/tests.py

import uuid
from specleft.discovery.models import SupportedLanguage, MinerResult, DiscoveredItem, ItemKind, TestFunctionMeta
from specleft.discovery.context import MinerContext

class PythonTestMiner:
    miner_id = uuid.UUID("a7b21db5-0d22-41be-9902-7c725e63892e")
    name = "python_test_functions"
    languages = frozenset({SupportedLanguage.PYTHON})

    def mine(self, ctx: MinerContext) -> MinerResult: ...

Detection rules

File targeting: use ctx.file_index.files_matching("test_*.py", "*_test.py") — do NOT walk the filesystem directly.

Tree-sitter queries (via ctx.registry.parse(file_path)):

• Top-level functions where name starts with test_
• Methods inside a class where the class name starts with Test

Framework detection: read from ctx.frameworks[SupportedLanguage.PYTHON] — do NOT re-detect. The FrameworkDetector has already resolved this.

Typed metadata

Each item's metadata dict must conform to TestFunctionMeta:

TestFunctionMeta(
    framework       = ctx.frameworks.get(SupportedLanguage.PYTHON, ["unknown"])[0],
    class_name      = "TestLogin" | None,
    decorators      = ["pytest.mark.parametrize"],
    has_docstring   = True,
    docstring       = "Test that valid credentials...",
    is_parametrized = True,
)

Pass meta.model_dump() as the metadata dict when constructing DiscoveredItem.

name: raw function name (e.g. test_valid_credentials)
language: SupportedLanguage.PYTHON
confidence: 0.9 for test_ prefix + known framework; 0.7 otherwise

Error handling

Return MinerResult(error_kind=MinerErrorKind.PARSE_ERROR, error="...") for files that fail to parse, not exceptions. Continue processing remaining files.

Acceptance criteria

• Given a fixture with 3 test functions (1 plain, 1 parametrized, 1 inside TestCase), miner returns exactly 3 items
• All items have language=SupportedLanguage.PYTHON
• Each item's metadata validates against TestFunctionMeta (no ValidationError)
• is_parametrized=True set correctly for the parametrized function
• class_name populated for the TestCase method, None for top-level functions
• Uses ctx.file_index.files_matching() — does not walk filesystem
• Uses ctx.frameworks — does not re-detect framework
• Parse errors on individual files produce error_kind=PARSE_ERROR on the result, not exceptions
• Tests in tests/discovery/miners/test_python_tests.py using fixtures from tests/fixtures/discovery/
• Update scenarios and tests in features/feature-spec-discovery.md to cover the functionality introduced by this issue

[Dimwiddle]

Implementation Notes

Branch: feature/discovery-layer-127-python-test-miner
Approach: Implemented a Python test-function miner that reads candidate files from shared FileIndex, parses via LanguageRegistry, emits typed TestFunctionMeta, and continues extraction when individual files fail to parse.

Decisions

• Keep framework source as ctx.frameworks[SupportedLanguage.PYTHON] to avoid duplicate framework detection logic.
• Capture parse failures in MinerResult.error/error_kind while still returning discovered items from successfully parsed files.
• Use lazy exports in miners/shared/__init__.py plus direct imports in default registries to avoid circular miner-package initialization.
• Update LanguageRegistry to tree-sitter 0.25 parser API (parser.language = ...) and remove stale mypy ignores needed for current lint rules.

Tasks

• Add PythonTestMiner in src/specleft/discovery/miners/python/tests.py with detection + metadata mapping
• Export/register the miner in package init files and default pipeline wiring
• Add unit tests in tests/discovery/miners/test_python_tests.py for plain, parametrized, class methods, framework usage, and parse failures
• Update features/feature-spec-discovery.md scenarios for issue Discovery miner: Python test functions (pytest, unittest) #127 behavior
• Run make lint-fix && make lint && make test and resolve any failures
• Commit and push atomic changes with issue-linked commit message