You have learned how to use **Python lists** to store HR data and how to perform calculations using elements from these lists. When analyzing employee turnover, it is common to have two lists: one containing the number of **employee departures** for each year, and another containing the **average headcount** for each year. By processing these lists **element-wise**, you can calculate important HR metrics such as the **turnover rate** for each year.

departures_per_year = [8, 10, 7, 12]
average_headcount_per_year = [80, 85, 83, 90]
years = [2020, 2021, 2022, 2023]

for year, departures, headcount in zip(years, departures_per_year, average_headcount_per_year):
    turnover_rate = departures / headcount
    print(f"Year: {year} - Turnover Rate: {turnover_rate:.2%}")

When presenting turnover rates, it is helpful to display both the year and the calculated percentage in a clear format. You can use Python's **formatted string literals** (`f-strings`) to include the year and format the turnover rate as a percentage with two decimal places. This makes your output easy for stakeholders to read and interpret.


import unittest
import user_code
import ast
import re   
import importlib
import csv
import unittest
import importlib
import io
from contextlib import redirect_stdout

class TestTask(unittest.TestCase):
    def test_output_lines_and_content(self):
        import user_code

        importlib.reload(user_code)
        f = io.StringIO()
        with redirect_stdout(f):
            user_code.print_turnover_rates(
                [2020, 2021, 2022],
                [5, 8, 6],
                [50, 60, 55]
            )
        output = f.getvalue().strip().splitlines()
        expected = [
            "Year: 2020 - Turnover Rate: 10.00%",
            "Year: 2021 - Turnover Rate: 13.33%",
            "Year: 2022 - Turnover Rate: 10.91%"
        ]
        _dynamic_test(
            self,
            len(output) == len(expected),
            "Correct number of output lines for each year",
            f"Expected {len(expected)} lines, got {len(output)}: {output}",
        )
        for i in range(len(expected)):
            _dynamic_test(
                self,
                normalize_text(expected[i]) == normalize_text(output[i]),
                f"Line {i+1} output is correct",
                f"Expected '{expected[i]}', got '{output[i]}'",
            )

    def test_turnover_rate_calculation(self):
        import user_code
        importlib.reload(user_code)
        years = [2018, 2019]
        departures = [2, 3]
        headcounts = [20, 30]
        f = io.StringIO()
        with redirect_stdout(f):
            user_code.print_turnover_rates(years, departures, headcounts)
        output = f.getvalue()
        _dynamic_test(
            self,
            "2018" in output and "10.00%" in output,
            "Turnover rate for 2018 is calculated and printed correctly",
            f"Expected turnover rate 10.00% for 2018 in output: {output}",
        )
        _dynamic_test(
            self,
            "2019" in output and "10.00%" in output,
            "Turnover rate for 2019 is calculated and printed correctly",
            f"Expected turnover rate 10.00% for 2019 in output: {output}",
        )

    def test_handles_empty_lists(self):
        import user_code
        importlib.reload(user_code)
        f = io.StringIO()
        with redirect_stdout(f):
            user_code.print_turnover_rates([], [], [])
        output = f.getvalue().strip()
        _dynamic_test(
            self,
            output == "",
            "No output is printed for empty input lists",
            f"Expected no output for empty lists, got: '{output}'",
        )

def _dynamic_test(test_case, condition, success_message, failure_message):
    if condition:
        test_case._testMethodName = success_message
        test_case.assertTrue(True, success_message)
    else:
        test_case._testMethodName = failure_message
        test_case.fail(failure_message)

def normalize_text(text):
    text = text.lower()
    text = re.sub(r"\\s{2,}", " ", text)
    text = re.sub(r"\\s*([,:?])\\s*", r"\\1 ", text)
    return text.strip()

def change_var(code: str, var_name: str, value: str) -> str:
    tree = ast.parse(code)
    lines = code.splitlines()
    changed = False
    # Collect all assignment nodes to modify
    assign_nodes = [
        (i, node)
        for i, node in enumerate(tree.body)
        if isinstance(node, ast.Assign)
        and any(isinstance(target, ast.Name) and target.id == var_name for target in node.targets)
    ]

    # If nothing to change, return unmodified code
    if not assign_nodes:
        return code

    # Perform replacements for all matching assignments (from last to first to not break line offsets)
    for i, node in reversed(assign_nodes):
        start_line = node.lineno - 1
        line = lines[start_line]
        indent = ' ' * (len(line) - len(line.lstrip()))
        lines[start_line] = f"{indent}{var_name} = {value}"
        next_line = len(lines)
        for next_node in tree.body[i+1:]:
            if hasattr(next_node, 'lineno'):
                next_line = next_node.lineno - 1
                break
        if next_line > start_line + 1:
            lines[start_line+1:next_line] = []
        changed = True

    return '\\n'.join(lines) if changed else code

if __name__ == "__main__":
    unittest.main()


test_main.py

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Challenge: Yearly Turnover Analysis

解答