import unittest
import psycopg2
import pandas as pd
import re

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_returns_all_rows(self):
        """Check that all rows from sales table are returned."""
        with open("query.sql", "r") as file:
            query = file.read()
        self.cursor.execute("SELECT COUNT(*) FROM sales;")
        expected_count = self.cursor.fetchone()[0]
        self.cursor.execute(query)
        rows = self.cursor.fetchall()
        condition = len(rows) == expected_count
        _dynamic_test(
            self,
            condition,
            "Query returns all rows from sales table.",
            f"Query does not return all rows. Expected {expected_count}, got {len(rows)}."
        )

    def test_discount_eligible_column_present(self):
        """Check that discount_eligible column is present in result."""
        with open("query.sql", "r") as file:
            query = file.read()
        self.cursor.execute(query)
        columns = [desc[0] for desc in self.cursor.description]
        condition = "discount_eligible" in [normalize_text(col) for col in columns]
        _dynamic_test(
            self,
            condition,
            "discount_eligible column is present in result.",
            "discount_eligible column is missing in result."
        )

    def test_discount_eligible_yes(self):
        """Check that rows with region East or West have discount_eligible = 'Yes'."""
        with open("query.sql", "r") as file:
            query = file.read()
        self.cursor.execute(query)
        columns = [desc[0] for desc in self.cursor.description]
        rows = self.cursor.fetchall()
        df = pd.DataFrame(rows, columns=columns)
        if 'discount_eligible' not in df.columns or 'region' not in df.columns:
            _dynamic_test(self, False, "", "discount_eligible or region column missing.")
            return
        subset = df[df['region'].isin(['East', 'West'])]
        condition = all(subset['discount_eligible'] == 'Yes')
        _dynamic_test(
            self,
            condition,
            "Rows with region East or West have discount_eligible = 'Yes'.",
            "Some rows with region East or West do not have discount_eligible = 'Yes'."
        )

    def test_discount_eligible_no(self):
        """Check that rows with region not East or West have discount_eligible = 'No'."""
        with open("query.sql", "r") as file:
            query = file.read()
        self.cursor.execute(query)
        columns = [desc[0] for desc in self.cursor.description]
        rows = self.cursor.fetchall()
        df = pd.DataFrame(rows, columns=columns)
        if 'discount_eligible' not in df.columns or 'region' not in df.columns:
            _dynamic_test(self, False, "", "discount_eligible or region column missing.")
            return
        subset = df[~df['region'].isin(['East', 'West'])]
        condition = all(subset['discount_eligible'] == 'No')
        _dynamic_test(
            self,
            condition,
            "Rows with region not East or West have discount_eligible = 'No'.",
            "Some rows with region not East or West do not have discount_eligible = 'No'."
        )


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：Regional Discount Flag

解答