import unittest
import psycopg2
import pandas as pd

class TestPostgresQuery(unittest.TestCase):
    @classmethod
    def setUpClass(cls):
        cls.connection = psycopg2.connect(
            host="localhost",
            user="agent",
            password="qwerty",
            dbname="testdb",
            sslmode="disable"
        )
        cls.cursor = cls.connection.cursor()

    def _get_user_query(self):
        with open("query.sql", "r") as file:
            return file.read()

    def test_columns_present(self):
        query = self._get_user_query()
        self.cursor.execute(query)
        columns = [desc[0] for desc in self.cursor.description]
        required_columns = ["sale_id", "sale_date", "employee_id", "amount", "running_total"]
        missing = [col for col in required_columns if col not in columns]
        _dynamic_test(
            self,
            len(missing) == 0,
            "All required columns are present.",
            f"Missing columns: {', '.join(missing)}"
        )

    def test_result_ordering(self):
        query = self._get_user_query()
        self.cursor.execute(query)
        rows = self.cursor.fetchall()
        columns = [desc[0] for desc in self.cursor.description]
        df = pd.DataFrame(rows, columns=columns)
        if df.empty:
            _dynamic_test(self, False, "Result is not empty.", "Query returned no results.")
            return
        sorted_df = df.sort_values(by=["employee_id", "sale_date", "sale_id"]).reset_index(drop=True)
        is_sorted = df.reset_index(drop=True).equals(sorted_df)
        _dynamic_test(
            self,
            is_sorted,
            "Result is ordered by employee_id, sale_date, sale_id.",
            "Result is not ordered by employee_id, sale_date, sale_id."
        )

    def test_running_total_correct(self):
        query = self._get_user_query()
        self.cursor.execute(query)
        rows = self.cursor.fetchall()
        columns = [desc[0] for desc in self.cursor.description]
        df = pd.DataFrame(rows, columns=columns)
        error_msgs = []
        for emp_id, group in df.groupby("employee_id"):
            group = group.sort_values(["sale_date", "sale_id"])
            running_sum = 0
            for idx, row in group.iterrows():
                running_sum += float(row["amount"])
                actual = float(row["running_total"])
                if abs(running_sum - actual) > 0.01:
                    error_msgs.append(f"Employee {emp_id}, sale_id {row['sale_id']}: expected {running_sum}, got {actual}")
        _dynamic_test(
            self,
            len(error_msgs) == 0,
            "Running total is correct for all employees.",
            "\\n".join(error_msgs)
        )

    def test_running_total_non_decreasing(self):
        query = self._get_user_query()
        self.cursor.execute(query)
        rows = self.cursor.fetchall()
        columns = [desc[0] for desc in self.cursor.description]
        df = pd.DataFrame(rows, columns=columns)
        error_msgs = []
        for emp_id, group in df.groupby("employee_id"):
            group = group.sort_values(["sale_date", "sale_id"])
            prev = None
            for idx, row in group.iterrows():
                current = float(row["running_total"])
                if prev is not None and current < prev - 0.01:
                    error_msgs.append(f"Employee {emp_id}, sale_id {row['sale_id']}: running_total decreased from {prev} to {current}")
                prev = current
        _dynamic_test(
            self,
            len(error_msgs) == 0,
            "Running total never decreases for each employee.",
            "\\n".join(error_msgs)
        )

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

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


test_solution.py

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Challenge: Calculate Running Total of Sales

Solution

Challenge: Calculate Running Total of Sales

Solution