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 test_all_columns_and_price_tier(self):
        """Check that all original columns and the price_tier column are present."""
        with open("query.sql", "r") as file:
            query = file.read()
        self.cursor.execute(query)
        columns = [desc[0] for desc in self.cursor.description]
        expected = set(["id", "product", "quantity", "price", "region", "price_tier"])
        condition = expected.issubset(set(columns))
        _dynamic_test(
            self,
            condition,
            "All required columns including price_tier are present.",
            f"Missing columns: {expected - set(columns)}"
        )

    def test_premium_price_tier(self):
        """Check that price_tier is 'Premium' for price > 700."""
        with open("query.sql", "r") as file:
            query = file.read()
        self.cursor.execute(query)
        rows = self.cursor.fetchall()
        columns = [desc[0] for desc in self.cursor.description]
        df = pd.DataFrame(rows, columns=columns)
        premium_rows = df[df['price'] > 700]
        if not premium_rows.empty:
            condition = all(premium_rows['price_tier'] == 'Premium')
        else:
            condition = True
        _dynamic_test(
            self,
            condition,
            "All price > 700 rows are labeled 'Premium'.",
            "Some price > 700 rows are not labeled 'Premium'."
        )

    def test_standard_price_tier(self):
        """Check that price_tier is 'Standard' for price between 300 and 700 inclusive."""
        with open("query.sql", "r") as file:
            query = file.read()
        self.cursor.execute(query)
        rows = self.cursor.fetchall()
        columns = [desc[0] for desc in self.cursor.description]
        df = pd.DataFrame(rows, columns=columns)
        standard_rows = df[(df['price'] >= 300) & (df['price'] <= 700)]
        if not standard_rows.empty:
            condition = all(standard_rows['price_tier'] == 'Standard')
        else:
            condition = True
        _dynamic_test(
            self,
            condition,
            "All price between 300 and 700 rows are labeled 'Standard'.",
            "Some price between 300 and 700 rows are not labeled 'Standard'."
        )

    def test_budget_price_tier(self):
        """Check that price_tier is 'Budget' for price < 300."""
        with open("query.sql", "r") as file:
            query = file.read()
        self.cursor.execute(query)
        rows = self.cursor.fetchall()
        columns = [desc[0] for desc in self.cursor.description]
        df = pd.DataFrame(rows, columns=columns)
        budget_rows = df[df['price'] < 300]
        if not budget_rows.empty:
            condition = all(budget_rows['price_tier'] == 'Budget')
        else:
            condition = True
        _dynamic_test(
            self,
            condition,
            "All price < 300 rows are labeled 'Budget'.",
            "Some price < 300 rows are not labeled 'Budget'."
        )


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()

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


test_solution.py

SQLにおけるCASE WHEN文を基礎的な条件分岐からデータ分析・レポーティングでの高度な活用例まで習得できる包括的なモジュールです。理論と実践的な課題を通じて、複雑なビジネス要件に対応する表現力豊かなクエリの作成方法を学びます。

CASE WHEN文の基本、構文、およびSQLクエリでの単純な条件付きロジックへの活用方法を学習します。

チャレンジ：価格帯の割り当て

解答