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 setUp(self):
        self.cursor.execute("ROLLBACK")
        self.cursor.execute("BEGIN")

    def test_all_direct_and_indirect_subordinates(self):
        """Returns all direct and indirect subordinates of the specified manager (employee_id = 2)."""
        with open("query.sql", "r") as file:
            query = file.read()

        # Expected subordinates for Bob Smith (employee_id = 2):
        # David Brown (4), Eve Black (5), Frank Green (6), Grace Lee (7)
        # Levels: David=1, Eve=2, Frank/Grace=3
        expected = [
            (4, "David Brown", "Engineering Manager", 1),
            (5, "Eve Black", "Lead Developer", 2),
            (6, "Frank Green", "Developer", 3),
            (7, "Grace Lee", "Developer", 3),
        ]
        expected_df = pd.DataFrame(expected, columns=["employee_id", "name", "position", "reporting_level"])

        self.cursor.execute(query)
        rows = self.cursor.fetchall()
        columns = [desc[0] for desc in self.cursor.description]
        result_df = pd.DataFrame(rows, columns=columns)

        # Check each expected row is present
        missing_rows = []
        for _, expected_row in expected_df.iterrows():
            mask = (
                (result_df["employee_id"] == expected_row["employee_id"]) &
                (result_df["name"] == expected_row["name"]) &
                (result_df["position"] == expected_row["position"]) &
                (result_df["reporting_level"] == expected_row["reporting_level"])
            )
            if not mask.any():
                missing_rows.append(dict(expected_row))

        condition = len(missing_rows) == 0
        failure_msg = "Missing expected subordinates: " + ", ".join(str(r) for r in missing_rows) if missing_rows else ""
        _dynamic_test(
            self,
            condition,
            "All direct and indirect subordinates are present.",
            failure_msg
        )

    def test_reporting_levels_correct(self):
        """Each subordinate has the correct reporting level."""
        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]
        result_df = pd.DataFrame(rows, columns=columns)

        # Map employee_id to correct reporting_level
        correct_levels = {
            4: 1,  # David Brown
            5: 2,  # Eve Black
            6: 3,  # Frank Green
            7: 3,  # Grace Lee
        }
        incorrect = []
        for eid, level in correct_levels.items():
            found = result_df[result_df["employee_id"] == eid]
            if found.empty or found.iloc[0]["reporting_level"] != level:
                incorrect.append((eid, level))
        condition = len(incorrect) == 0
        failure_msg = "Incorrect reporting levels for: " + ", ".join(str(r) for r in incorrect) if incorrect else ""
        _dynamic_test(
            self,
            condition,
            "All reporting levels are correct.",
            failure_msg
        )

    def test_only_subordinates_included(self):
        """Only employees who report (directly or indirectly) to the specified manager are included."""
        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]
        result_df = pd.DataFrame(rows, columns=columns)
        # Bob Smith's subordinates are 4,5,6,7
        allowed_ids = {4,5,6,7}
        extra = result_df[~result_df["employee_id"].isin(allowed_ids)]
        condition = extra.empty
        failure_msg = f"Found employees not reporting to the specified manager: {extra['employee_id'].tolist()}" if not extra.empty else ""
        _dynamic_test(
            self,
            condition,
            "No unrelated employees included.",
            failure_msg
        )

    def test_output_columns(self):
        """Output columns include employee_id, name, position, and reporting_level."""
        with open("query.sql", "r") as file:
            query = file.read()
        self.cursor.execute(query)
        columns = [desc[0] for desc in self.cursor.description]
        required = {"employee_id", "name", "position", "reporting_level"}
        condition = required.issubset(set(columns))
        failure_msg = f"Missing columns: {required - set(columns)}" if not condition else ""
        _dynamic_test(
            self,
            condition,
            "All required output columns are present.",
            failure_msg
        )

    def test_ordering(self):
        """Results are ordered by reporting_level and employee_id."""
        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]
        result_df = pd.DataFrame(rows, columns=columns)
        if not result_df.empty:
            sorted_df = result_df.sort_values(["reporting_level", "employee_id"]).reset_index(drop=True)
            condition = result_df.reset_index(drop=True).equals(sorted_df)
        else:
            condition = True
        failure_msg = "Results are not ordered by reporting_level and employee_id."
        _dynamic_test(
            self,
            condition,
            "Results are ordered correctly.",
            failure_msg
        )

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

A comprehensive course designed to help you master Common Table Expressions (CTEs) in SQL, from foundational concepts to advanced real-world applications. Explore recursive queries, modular query design, and performance considerations through engaging theory and practical, scenario-based tasks.

Explore the basics of Common Table Expressions, their syntax, and how they can simplify SQL queries. Practice using CTEs in real-world scenarios such as reporting and data transformation.

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Challenge: Organizational Hierarchy Traversal

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