CSV files

def load_scores(path: str) -> dict[str, int]:
    totals: dict[str, int] = {}
    with open(path, encoding="utf-8") as f:
        next(f)  # skip the header
        for line in f:
            name, points = line.strip().split(",")
            totals[name] = totals.get(name, 0) + int(points)
    return totals


if __name__ == "__main__":
    print(load_scores("scores.csv"))

from main import load_scores


def write(path, text):
    with open(path, "w", newline="", encoding="utf-8") as f:
        f.write(text)


def test_given_file():
    """The given file gives 7 points for Ada and 5 for Grace"""
    got = load_scores("scores.csv")
    assert got == {"Lovelace, Ada": 7, "Hopper, Grace": 5}, f"load_scores returned {got!r}"


def test_other_column_order():
    """Columns in another order are read by name"""
    write("t_order.csv", "points,name\n2,Bo\n3,Bo\n")
    got = load_scores("t_order.csv")
    assert got == {"Bo": 5}, f"for points,name the function returned {got!r}"


def test_header_only():
    """A file with only a header gives {}"""
    write("t_empty.csv", "name,points\n")
    got = load_scores("t_empty.csv")
    assert got == {}, f"for a header-only file the function returned {got!r}"

name,points
"Lovelace, Ada",3
"Hopper, Grace",5
"Lovelace, Ada",4

def export_semicolon(src: str, dst: str) -> int:
    with open(src, encoding="utf-8") as f:
        text = f.read()
    with open(dst, "w", encoding="utf-8") as f:
        f.write(text.replace(",", ";"))
    return 0


if __name__ == "__main__":
    with open("people.csv", "w", newline="", encoding="utf-8") as f:
        f.write('name,city\nAda,"Berlin; Mitte"\n')
    print(export_semicolon("people.csv", "people_de.csv"))

import csv

from main import export_semicolon

SOURCE = 'name,city\nAda,"Berlin; Mitte"\nBo,"Köln, Süd"\n'


def export(text):
    with open("t_src.csv", "w", newline="", encoding="utf-8") as f:
        f.write(text)
    count = export_semicolon("t_src.csv", "t_dst.csv")
    with open("t_dst.csv", newline="", encoding="utf-8") as f:
        return count, f.read()


def test_count():
    """Two data rows give 2"""
    count, text = export(SOURCE)
    assert count == 2, f"export_semicolon returned {count!r}, expected 2"


def test_round_trip():
    """Read back with delimiter=';', the rows are unchanged"""
    count, text = export(SOURCE)
    with open("t_dst.csv", newline="", encoding="utf-8") as f:
        rows = list(csv.reader(f, delimiter=";"))
    want = [["name", "city"], ["Ada", "Berlin; Mitte"], ["Bo", "Köln, Süd"]]
    assert rows == want, f"reading the new file with delimiter=';' gave {rows!r}"


def test_file_text():
    """The file uses ; and \\r\\n, and quotes only the field with a ;"""
    count, text = export(SOURCE)
    want = 'name;city\r\nAda;"Berlin; Mitte"\r\nBo;Köln, Süd\r\n'
    assert text == want, f"the new file holds {text!r}"