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_returns_all_direct_and_indirect_dependencies(self):
        """Check that all direct and indirect dependencies are returned for task_id = 6 (Deployment)."""
        with open("query.sql", "r") as file:
            query = file.read()

        # Expected: Deployment (6) depends on Testing (5), which depends on Frontend (3) and Backend (4),
        # Frontend (3) depends on Design Mockups (2), which depends on Requirements Gathering (1)
        # Backend (4) depends on Design Mockups (2) as well
        expected = set([
            (1, 'Requirements Gathering'),
            (2, 'Design Mockups'),
            (3, 'Frontend Development'),
            (4, 'Backend Development'),
            (5, 'Testing')
        ])
        self.cursor.execute(query)
        rows = self.cursor.fetchall()
        result = set((row[0], row[1]) for row in rows)
        missing = expected - result
        extra = result - expected
        condition = len(missing) == 0 and len(extra) == 0
        failure_msg = "Missing: {}. Extra: {}".format(missing, extra) if not condition else ""
        _dynamic_test(self, condition, "All direct and indirect dependencies are returned for task_id = 6.", failure_msg)

    def test_does_not_include_specified_task(self):
        """Check that the specified task_id itself is not included in the result."""
        with open("query.sql", "r") as file:
            query = file.read()
        self.cursor.execute(query)
        rows = self.cursor.fetchall()
        ids = [row[0] for row in rows]
        condition = 6 not in ids
        _dynamic_test(self, condition, "Specified task_id is not included in the results.", "Specified task_id=6 was included in the results.")

    def test_returns_task_id_and_task_name(self):
        """Check that both task_id and task_name are returned in the 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 = ('prereq_task_id' in columns or 'task_id' in columns) and ('prereq_task_name' in columns or 'task_name' in columns)
        _dynamic_test(self, condition, "Result includes both task_id and task_name columns.", "Result must include both task_id and task_name columns.")

    def test_multiple_dependencies(self):
        """Check that a task with multiple dependencies at any level returns all prerequisites (task_id = 5)."""
        # For task_id = 5 (Testing): depends on 3 (Frontend Development) and 4 (Backend Development)
        # 3 depends on 2, 2 depends on 1; 4 depends on 2
        query = """
        WITH RECURSIVE task_prereqs AS (
            SELECT td.depends_on_task_id AS prereq_task_id, pt.task_name AS prereq_task_name
            FROM task_dependencies td JOIN project_tasks pt ON td.depends_on_task_id = pt.task_id
            WHERE td.task_id = 5
            UNION
            SELECT td.depends_on_task_id AS prereq_task_id, pt.task_name AS prereq_task_name
            FROM task_dependencies td JOIN project_tasks pt ON td.depends_on_task_id = pt.task_id
            JOIN task_prereqs tp ON td.task_id = tp.prereq_task_id
        )
        SELECT prereq_task_id, prereq_task_name FROM task_prereqs ORDER BY prereq_task_id;
        """
        expected = set([
            (1, 'Requirements Gathering'),
            (2, 'Design Mockups'),
            (3, 'Frontend Development'),
            (4, 'Backend Development')
        ])
        self.cursor.execute(query)
        rows = self.cursor.fetchall()
        result = set((row[0], row[1]) for row in rows)
        missing = expected - result
        extra = result - expected
        condition = len(missing) == 0 and len(extra) == 0
        failure_msg = "Missing: {}. Extra: {}".format(missing, extra) if not condition else ""
        _dynamic_test(self, condition, "All prerequisites for a task with multiple dependencies are returned.", failure_msg)

    def test_no_dependencies_returns_empty(self):
        """Check that a task with no dependencies returns zero rows (task_id = 1)."""
        query = """
        WITH RECURSIVE task_prereqs AS (
            SELECT td.depends_on_task_id AS prereq_task_id, pt.task_name AS prereq_task_name
            FROM task_dependencies td JOIN project_tasks pt ON td.depends_on_task_id = pt.task_id
            WHERE td.task_id = 1
            UNION
            SELECT td.depends_on_task_id AS prereq_task_id, pt.task_name AS prereq_task_name
            FROM task_dependencies td JOIN project_tasks pt ON td.depends_on_task_id = pt.task_id
            JOIN task_prereqs tp ON td.task_id = tp.prereq_task_id
        )
        SELECT prereq_task_id, prereq_task_name FROM task_prereqs;
        """
        self.cursor.execute(query)
        rows = self.cursor.fetchall()
        condition = len(rows) == 0
        _dynamic_test(self, condition, "Task with no dependencies returns zero rows.", "Task with no dependencies did not return zero rows.")

    def test_indirect_dependencies_for_other_project(self):
        """Check indirect dependencies for a task in the second project (task_id = 12)."""
        # 12 depends on 11, which depends on 9, which depends on 8, which depends on 7
        query = """
        WITH RECURSIVE task_prereqs AS (
            SELECT td.depends_on_task_id AS prereq_task_id, pt.task_name AS prereq_task_name
            FROM task_dependencies td JOIN project_tasks pt ON td.depends_on_task_id = pt.task_id
            WHERE td.task_id = 12
            UNION
            SELECT td.depends_on_task_id AS prereq_task_id, pt.task_name AS prereq_task_name
            FROM task_dependencies td JOIN project_tasks pt ON td.depends_on_task_id = pt.task_id
            JOIN task_prereqs tp ON td.task_id = tp.prereq_task_id
        )
        SELECT prereq_task_id, prereq_task_name FROM task_prereqs ORDER BY prereq_task_id;
        """
        expected = set([
            (7, 'Market Research'),
            (8, 'Product Design'),
            (9, 'Prototype Development'),
            (11, 'Marketing Campaign')
        ])
        self.cursor.execute(query)
        rows = self.cursor.fetchall()
        result = set((row[0], row[1]) for row in rows)
        missing = expected - result
        extra = result - expected
        condition = len(missing) == 0 and len(extra) == 0
        failure_msg = "Missing: {}. Extra: {}".format(missing, extra) if not condition else ""
        _dynamic_test(self, condition, "All indirect dependencies for task_id = 12 are returned.", 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: Project Task Dependency Resolution

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