import unittest
import user_code
import ast
import re   
import importlib
import csv
import polars as pl

class TestTask(unittest.TestCase):
    def setUp(self):
        # Mock dataset designed to test boundaries: Free, Budget (exact 10.0), Premium, and invalid Positive values
        self.df = pl.DataFrame({
            "Name": ["Freebie", "Cheap Game", "Exact Ten", "Expensive", "No Reviews", "Negative Reviews"],
            "Price": [0.0, 4.99, 10.0, 14.99, 0.0, 5.0],
            "Positive": [100, 50, 25, 200, 0, -5]
        })

    def test_function_and_columns_exist(self):
        import user_code
        importlib.reload(user_code)
        func = getattr(user_code, "filter_and_tier_games", None)
        
        _dynamic_test(
            self,
            callable(func),
            "filter_and_tier_games function exists and is callable.",
            "filter_and_tier_games function is missing or not callable."
        )
        
        result = func(self.df)
        _dynamic_test(
            self,
            result is not None and "Price Tier" in result.columns,
            "Returned DataFrame contains 'Price Tier' column.",
            "Returned DataFrame is missing 'Price Tier' column."
        )

    def test_filtering_logic_correct(self):
        import user_code
        importlib.reload(user_code)
        func = getattr(user_code, "filter_and_tier_games", None)
        result = func(self.df)
        
        # 'No Reviews' (0) and 'Negative Reviews' (-5) should be filtered out
        expected_names = ["Freebie", "Cheap Game", "Exact Ten", "Expensive"]
        
        if result is not None:
            actual_names = result["Name"].to_list()
            _dynamic_test(
                self,
                actual_names == expected_names,
                "Filtering logic correctly retains only games with Positive > 0.",
                f"Filtering logic failed. Expected games: {expected_names}, Got: {actual_names}"
            )
        else:
            _dynamic_test(self, False, "", "Returned DataFrame is None.")

    def test_price_tier_values_correct(self):
        import user_code
        importlib.reload(user_code)
        func = getattr(user_code, "filter_and_tier_games", None)
        result = func(self.df)
        
        # Expected tiers corresponding to the filtered games
        expected_tiers = ["Free", "Budget", "Budget", "Premium"]
        
        if result is not None and "Price Tier" in result.columns:
            actual_tiers = result["Price Tier"].to_list()
            _dynamic_test(
                self,
                actual_tiers == expected_tiers,
                "'Price Tier' column contains correct classifications (Free, Budget, Premium).",
                f"'Price Tier' values incorrect. Expected: {expected_tiers}, Got: {actual_tiers}"
            )
        else:
            _dynamic_test(self, False, "", "Result missing 'Price Tier' column.")

    def test_original_columns_preserved(self):
        import user_code
        importlib.reload(user_code)
        func = getattr(user_code, "filter_and_tier_games", None)
        result = func(self.df)
        
        if result is not None:
            for col in ["Name", "Price", "Positive"]:
                _dynamic_test(
                    self,
                    col in result.columns,
                    f"Context verification passed: Column '{col}' was preserved.",
                    f"Context verification failed: Column '{col}' is missing."
                )
        else:
            _dynamic_test(self, False, "", "Returned DataFrame is None.")

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()

def change_var(code: str, var_name: str, value: str) -> str:
    tree = ast.parse(code)
    lines = code.splitlines()
    changed = False
    assign_nodes = [
        (i, node)
        for i, node in enumerate(tree.body)
        if isinstance(node, ast.Assign)
        and any(isinstance(target, ast.Name) and target.id == var_name for target in node.targets)
    ]

    if not assign_nodes:
        return code

    for i, node in reversed(assign_nodes):
        start_line = node.lineno - 1
        line = lines[start_line]
        indent = ' ' * (len(line) - len(line.lstrip()))
        lines[start_line] = f"{indent}{var_name} = {value}"
        next_line = len(lines)
        for next_node in tree.body[i+1:]:
            if hasattr(next_node, 'lineno'):
                next_line = next_node.lineno - 1
                break
        if next_line > start_line + 1:
            lines[start_line+1:next_line] = []
        changed = True

    return '\\n'.join(lines) if changed else code

if __name__ == "__main__":
    unittest.main(verbosity=2)

test_main.py

Dive into the fundamentals of data wrangling with Polars, using real-world Steam game datasets. Learn Polars' columnar paradigm, selection, aggregation, joining, reshaping, and essential string, date, and missing data operations.

Explore the core differences between Polars and traditional row-based DataFrames, focusing on columnar operations, selection, and conditional logic using the Steam games dataset.

Gain a solid understanding of Polars' parallel group-by, aggregation, joining, and reshaping capabilities using the Steam games and spy insights datasets.

Explore the essentials of data cleaning: text normalization, date parsing, and robust handling of missing values in Polars.

Challenge: Filtering & Conditional Logic

Solution