025-weather/docs/milestones/mil-002-read-with-csv.md

MIL-002: Read with the csv library

Metadata

Key	Value
ID	MIL-002
CrossReference	BC-001
Language	en
Domain	it

Version History

Date	Status	Author	Reviewer	Change	Commit
2026-10-13	Accepted	Jens Tirsvad Nielsen	AI as stand-in for S01	Initial version, reviewed in RC-005 (Go)	pending

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Purpose

This gate decides whether the first half of the first lecture is delivered: the weather data file is in the repository and its rows and temperatures are read with Python's built-in csv library, without any dependency. The work is delivered on the branch mil-002-read-with-csv and one pull request.

Deliverable

src/weather/weather_data.csv (the lecture's file, adopted unchanged), src/weather/csv_reader.py with read_rows and read_temperatures, and tests/test_csv_reader.py.

Go / No-Go Criteria

#	Criterion (objectively checkable)	Go	No-Go
1	The data file is the lecture's	Header day,temp,condition and 7 data rows, Monday to Sunday, identical to the file S01 downloaded	A different header, row count or content
2	read_rows returns the rows as lists of strings	The first element is ["day", "temp", "condition"]; 8 rows in all	Rows are not lists of strings or the header is lost
3	read_temperatures returns whole numbers without the header	[12, 14, 15, 14, 21, 22, 24], every element an int	A string in the list, the header word, or a wrong value
4	The default path does not depend on the working directory	Running from another folder finds the file; a path argument overrides the default	The call fails when started elsewhere
5	The file is closed and opened with with	Review of src/ finds no open outside with	A file left open
6	The module needs no dependency	import weather.csv_reader works with pandas not installed	An import of pandas in the module
7	Tests are green and use no file outside tmp_path	pytest exit code 0	A failing test, or a write outside a temporary folder
8	The code is reviewed	RC-* against QC-PY-001 has the verdict Go	Verdict No-Go or Go-with-conditions

Dependencies

Depends on	Reason
MIL-001 accepted and merged	The package, constants.py and the test set-up come from it

Traceability

Business Case objective / KPI / user story	Reference
Objective 1: the data file	BC-001, criterion 1 in Success Criteria
Objective 2: reading with csv	BC-001, criteria 2 and 10 in Success Criteria

Ownership

Role	Stakeholder ID (SA)
Owner	S01
Approving reviewer	S01

Target Date

2026-10-17 — second of five gateways, inside the plan of PP-001 that ends 2026-10-23.

Tasks

#	Task	Summary	Needs its own Use Case/User Story?	Reference
1	Add the weather data file	Copy weather_data.csv from S01's download folder to src/weather/weather_data.csv unchanged (header day,temp,condition, 7 rows). Add its name to constants.py. Serves objective 1.	No
2	Read the weather rows with the csv library	Add read_rows(path) in src/weather/csv_reader.py: open the file with with, read it with csv.reader and return the rows as a list of lists of strings, header included, as the lecture does. The default path is the data file next to the module. Serves objective 2.	No
3	Extract the temperatures as integers	Add read_temperatures(path): skip the header row, take the second value of each row and convert it with int, as the lecture does, returning the list temperatures. Serves objective 2.	No
4	Add the tests for the csv reader	Add tests/test_csv_reader.py: the real file gives [12, 14, 15, 14, 21, 22, 24], a small file in tmp_path gives its own values, the header is skipped, and importing the module needs no pandas.	No

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