refactor: split enums into Action and StockMarketOperation (#53)

[przemyslawbialon]

Closes #53. Unblocks #9 sub-issues (#56, #57, #58).

What changed from the first version of this PR

The first approach merged OperationType and Action into a single 5-value Action enum. Review feedback rightly pointed out that this loses a domain boundary: Transaction(action=Action.STOCK_SPLIT) would be syntactically valid, and CsvValidator (once wired in #9) would let a crypto CSV carry STOCK_SPLIT rows — neither makes sense.

This revised version keeps a clean separation:

• Action(BUY, SELL) — the transactional action, attribute of Transaction. Common to stocks and crypto.
• StockMarketOperation(BUY, SELL, DIVIDEND, SERVICE_FEE, STOCK_SPLIT) — classifier for rows in a stock-market CSV. Stock-only; crypto CSVs use Action directly because their row type coincides with transaction action.

The silent .value-based coercion flagged in TAX_LAW_AUDIT.md Issue #1 is replaced by an explicit StockMarketOperation.to_action() method that raises for non-transactional values.

Files touched (14)

• New: pit38/domain/stock/operations/stock_market_operation.py — enum with is_transaction() and to_action() helpers
• pit38/domain/transactions/action.py — BUY/SELL only; add __hash__ (custom __eq__ requires it for set membership, e.g. TransactionRowParser.OPERATIONS_HANDLED)
• pit38/domain/stock/operations/operation.py — drop obsolete OperationType class; keep thin Operation base
• pit38/domain/stock/operations/{dividend,service_fee,stock_split}.py — type = StockMarketOperation.X
• pit38/data_sources/stock_loader/factory.py — key by StockMarketOperation; call .to_action() explicitly when building Transaction
• pit38/data_sources/stock_loader/csv_loader.py — parse column into StockMarketOperation
• pit38/plugins/stock/revolut/{row,transaction_row,operation_row}_parser.py — migrated
• pit38/stock.py — filter_transactions uses isinstance(Transaction); other filter_* methods compare against StockMarketOperation.X
• tests/test_csv_validator.py — asserts original "BUY, SELL" error message (validator wired for crypto stays 2-value)
• TAX_LAW_AUDIT.md — Issue Create a service for business logic of stock transactions  #1 marked resolved, with explanation
• .gitignore — add .coverage, .coverage.*, htmlcov/

Why __hash__?

Action.__eq__ is custom (compares .value). Python requires __hash__ when __eq__ is overridden, or the enum becomes unhashable and can't be used in sets. This matters for e.g. TransactionRowParser.OPERATIONS_HANDLED = {StockMarketOperation.BUY, StockMarketOperation.SELL}. Added on both enums to be safe.

Verification

• .venv/bin/pytest tests/ → 92 passed
• pit38 stock -f example_format.csv -y 2025 → same output as main (profit +2 261.13 PLN, tax 429.61 PLN)
• pit38 crypto -f example_format.csv -y 2025 → same output as main (loss 29 271.00 PLN, tax 0)
• grep -r OperationType pit38/ tests/ returns only local BinanceOperationType (unrelated)
• grep -rE "Action\.(DIVIDEND|SERVICE_FEE|STOCK_SPLIT)" pit38/ tests/ returns nothing — the semantic boundary holds
• Sanity: Action.STOCK_SPLIT raises AttributeError — Transaction.action cannot be assigned a non-transactional value

Related

• Resolves TAX_LAW_AUDIT.md Issue Create a service for business logic of stock transactions  #1 via two-enum split + explicit conversion
• Unblocks Consolidate operation and transaction reading from csv #9 (refactor(#9 PR 2): BaseCsvLoader ABC and subclass loaders #56, refactor(#9 PR 3): Unify MultiSourcesLoader and wire CsvValidator #57, test(#9 PR 4): Add missing test coverage for stock and base loaders #58) — BaseCsvLoader ABC can now be generic over either enum, and per-loader validators receive the correct subset naturally

[codecov]

Codecov Report

❌ Patch coverage is 77.58621% with 13 lines in your changes missing coverage. Please review.
✅ All tests successful. No failed tests found.

Files with missing lines	Patch %	Lines
.../domain/stock/operations/stock_market_operation.py	77.27%	4 Missing and 1 partial ⚠️
pit38/domain/transactions/action.py	25.00%	2 Missing and 1 partial ⚠️
...it38/plugins/stock/revolut/operation_row_parser.py	50.00%	3 Missing ⚠️
pit38/data_sources/stock_loader/factory.py	66.66%	1 Missing ⚠️
pit38/stock.py	83.33%	1 Missing ⚠️

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