010-calc/docs/milestones/mil-002-calculator-core.md

MIL-002 Calculator core

Metadata

Key	Value
ID	MIL-002
CrossReference	PP-001, SA-001, BC-001

Version History

Date	Status	Author	Reviewer	Change	Commit
2026-10-04	Accepted	Jens Tirsvad Nielsen	S01	Initial version	pending

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Purpose

Decide whether the arithmetic core is correct and tested before the console interface is built on it.

Deliverable

src/calc/constants.py and src/calc/operations.py with add, subtract, multiply, divide and the OPERATIONS dictionary, plus tests/test_operations.py.

Go / No-Go Criteria

#	Criterion (objectively checkable)	Go	No-Go
1	The four operations return correct results in the tests	Met	Not met
2	Division by zero raises ZeroDivisionError	Met	Not met
3	OPERATIONS maps + - * / to the stored (not called) functions	Met	Not met
4	All constants live in constants.py	Met	Not met
5	Every function has a Doxygen comment	Met	Not met

Dependencies

Depends on	Reason
MIL-001	Needs the package layout and configuration

Traceability

Business Case objective / KPI / user story	Reference
Objectives 1 to 4	BC-001

Ownership

Role	Stakeholder ID (SA)
Owner	S01
Approving reviewer	S01

Target Date

2026-10-06

Tasks

#	Task	Summary	Needs its own Use Case/User Story?	Reference
1	Add constants module	constants.py holding operation symbols, answers, prompts, messages and the ASCII art, so no literals are scattered through the code.	No
2	Implement the four operations and the OPERATIONS dictionary	Functions add, subtract, multiply, divide and a dictionary mapping each symbol to its function, stored without calling them, as taught in the lecture.	No
3	Add operation tests	pytest tests for each operation, division by zero and the dictionary contents.	No

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