test(backend): add unit tests

backend/tests/test_models.py

@@ -0,0 +1,156 @@
+from sqlalchemy import select
+from sqlalchemy.ext.asyncio import AsyncSession
+from sqlalchemy.orm import selectinload
+
+from src.models import Category, Difficulty, Explanation, Pattern, Question, Solution
+
+
+async def test_create_category(db_session: AsyncSession) -> None:
+    category = Category(
+        name="Arrays",
+        slug="arrays",
+        description="Array manipulation problems",
+    )
+    db_session.add(category)
+    await db_session.commit()
+
+    result = await db_session.execute(select(Category))
+    categories = list(result.scalars().all())
+    assert len(categories) == 1
+    assert categories[0].name == "Arrays"
+    assert categories[0].slug == "arrays"
+
+
+async def test_create_pattern(db_session: AsyncSession) -> None:
+    pattern = Pattern(
+        name="Two Pointers",
+        slug="two-pointers",
+        description="Use two pointers to traverse data",
+        when_to_use="Sorted arrays, linked lists",
+    )
+    db_session.add(pattern)
+    await db_session.commit()
+
+    result = await db_session.execute(select(Pattern))
+    patterns = list(result.scalars().all())
+    assert len(patterns) == 1
+    assert patterns[0].name == "Two Pointers"
+
+
+async def test_create_question(db_session: AsyncSession) -> None:
+    question = Question(
+        title="Two Sum",
+        slug="two-sum",
+        difficulty=Difficulty.EASY,
+        description="Find two numbers that add up to target.",
+        leetcode_id=1,
+    )
+    db_session.add(question)
+    await db_session.commit()
+
+    result = await db_session.execute(select(Question))
+    questions = list(result.scalars().all())
+    assert len(questions) == 1
+    assert questions[0].title == "Two Sum"
+    assert questions[0].difficulty == Difficulty.EASY
+
+
+async def test_question_with_categories(db_session: AsyncSession) -> None:
+    category = Category(name="Arrays", slug="arrays")
+    question = Question(
+        title="Two Sum",
+        slug="two-sum",
+        difficulty=Difficulty.EASY,
+        description="Find two numbers.",
+    )
+    question.categories = [category]
+
+    db_session.add(question)
+    await db_session.commit()
+
+    result = await db_session.execute(select(Question))
+    q = result.scalar_one()
+    assert len(q.categories) == 1
+    assert q.categories[0].name == "Arrays"
+
+
+async def test_question_with_patterns(db_session: AsyncSession) -> None:
+    pattern = Pattern(name="Two Pointers", slug="two-pointers")
+    question = Question(
+        title="Two Sum",
+        slug="two-sum",
+        difficulty=Difficulty.EASY,
+        description="Find two numbers.",
+    )
+    question.patterns = [pattern]
+
+    db_session.add(question)
+    await db_session.commit()
+
+    result = await db_session.execute(select(Question))
+    q = result.scalar_one()
+    assert len(q.patterns) == 1
+    assert q.patterns[0].name == "Two Pointers"
+
+
+async def test_question_with_explanation(db_session: AsyncSession) -> None:
+    question = Question(
+        title="Two Sum",
+        slug="two-sum",
+        difficulty=Difficulty.EASY,
+        description="Find two numbers.",
+    )
+    db_session.add(question)
+    await db_session.flush()
+
+    explanation = Explanation(
+        question_id=question.id,
+        approach="Use hash map",
+        intuition="Store seen values",
+        time_complexity="O(n)",
+        space_complexity="O(n)",
+    )
+    db_session.add(explanation)
+    await db_session.commit()
+
+    result = await db_session.execute(
+        select(Question)
+        .options(selectinload(Question.explanation))
+        .where(Question.id == question.id)
+    )
+    loaded_question = result.scalar_one()
+    assert loaded_question.explanation is not None
+    assert loaded_question.explanation.time_complexity == "O(n)"
+
+
+async def test_question_with_solutions(db_session: AsyncSession) -> None:
+    question = Question(
+        title="Two Sum",
+        slug="two-sum",
+        difficulty=Difficulty.EASY,
+        description="Find two numbers.",
+    )
+    db_session.add(question)
+    await db_session.flush()
+
+    solution = Solution(
+        question_id=question.id,
+        approach_name="Hash Map",
+        code="def solve(): pass",
+        is_optimal=True,
+    )
+    db_session.add(solution)
+    await db_session.commit()
+
+    result = await db_session.execute(
+        select(Question).options(selectinload(Question.solutions)).where(Question.id == question.id)
+    )
+    loaded_question = result.scalar_one()
+    assert len(loaded_question.solutions) == 1
+    assert loaded_question.solutions[0].is_optimal is True
+
+
+async def test_difficulty_enum() -> None:
+    assert Difficulty.EASY.value == "easy"
+    assert Difficulty.MEDIUM.value == "medium"
+    assert Difficulty.HARD.value == "hard"