Category overhaul (#20)

Reviewed-on: #20
Co-authored-by: Mathias <mathias2784@web.de>

tests/test_category_edge_cases.py

@@ -0,0 +1,153 @@
+from datetime import date
+
+import pytest
+
+from src.models.category import Category, CategoryBudget
+from tests.factories import CategoryFactory
+
+
+class TestCategoryComputedFields:
+    """Tests for Category's computed fields and special methods."""
+
+    def test_hash_id_computed_field_simple(self):
+        """Test hash_id for single-level category."""
+        c = Category.from_str("single")
+        assert hasattr(c, "hash_id")
+        assert isinstance(c.hash_id, str)
+        # Hash should be deterministic for same inputs
+        c2 = Category.from_str("single")
+        assert c.hash_id == c2.hash_id
+
+    def test_hash_id_computed_field_nested(self):
+        """Test hash_id for multi-level category hierarchy."""
+        c1 = Category.from_str("level1:level2:level3")
+        assert hasattr(c1, "hash_id")
+
+        c2 = Category.from_str("level1:level2:level3")
+        assert c1.hash_id == c2.hash_id
+
+    def test_hash_id_different_hierarchy(self):
+        """Test that different hierarchies have different hash_ids."""
+        c1 = Category.from_str("A:B")
+        c2 = Category.from_str("A:C")
+        # Different last level -> different hash_id
+        assert c1.hash_id != c2.hash_id
+
+    def test_hash_id_same_name_different_parent(self):
+        """Test that same name but different parent gives different hash."""
+        root = Category(name="Budget")
+        cat1 = Category(name="Budget", parent=root)
+
+        # Create another with same name but no parent
+        orphan = Category.from_str("Budget")
+
+        assert cat1.hash_id != orphan.hash_id
+
+    def test_to_str_single_level(self):
+        """Test to_str() for single-level category."""
+        c = Category.from_str("single")
+        assert c.to_str() == "single"
+
+    def test_to_str_nested(self):
+        """Test to_str() for nested category."""
+        c = Category.from_str("parent:child:grandchild")
+        assert c.to_str() == "parent:child:grandchild"
+
+    def test_str_uses_to_str(self):
+        """Test that __str__ delegates to to_str()."""
+        c = Category.from_str("A:B:C")
+        assert str(c) == c.to_str() == "A:B:C"
+
+    def test_repr_simple(self):
+        """Test repr() for single-level category."""
+        c = Category.from_str("single")
+        expected = 'Category.from_str("single")'
+        assert repr(c) == expected
+
+    def test_repr_nested(self):
+        """Test repr() for nested category."""
+        c = Category.from_str("parent:child")
+        expected = 'Category.from_str("parent:child")'
+        assert repr(c) == expected
+
+
+class TestCategoryBudgetValidation:
+    """Tests for CategoryBudget's date range validation."""
+
+    def test_valid_budget_no_dates(self):
+        """Budget with None dates is valid."""
+        cat = CategoryFactory.build()
+        budget = CategoryBudget(
+            category=cat,
+            amount_eur=100.00,
+        )
+        assert budget.valid_from is None
+        assert budget.valid_to is None
+
+    def test_valid_budget_with_dates(self):
+        """Budget with valid date range is accepted."""
+
+        cat = CategoryFactory.build()
+        budget = CategoryBudget(
+            category=cat,
+            amount_eur=100.00,
+            valid_from=date(2026, 10, 1),
+            valid_to=date(2026, 10, 31),
+        )
+        assert budget.valid_from == date(2026, 10, 1)
+        assert budget.valid_to == date(2026, 10, 31)
+
+    def test_invalid_date_range_raises(self):
+        """Budget with valid_from > valid_to raises ValueError."""
+
+        cat = CategoryFactory.build()
+
+        with pytest.raises(ValueError) as exc_info:
+            CategoryBudget(
+                category=cat,
+                amount_eur=100.00,
+                valid_from=date(2026, 10, 31),
+                valid_to=date(2026, 10, 1),
+            )
+
+        assert "valid_from" in str(exc_info.value)
+        assert "valid_to" in str(exc_info.value)
+        assert "nor in order" in str(exc_info.value)
+
+    def test_valid_budget_exact_boundary(self):
+        """Budget with exact same from and to is valid (single day)."""
+
+        cat = CategoryFactory.build()
+        budget = CategoryBudget(
+            category=cat,
+            amount_eur=100.00,
+            valid_from=date(2026, 10, 1),
+            valid_to=date(2026, 10, 1),
+        )
+        assert budget.valid_from == date(2026, 10, 1)
+        assert budget.valid_to == date(2026, 10, 1)
+
+    def test_validation_preserves_original_values(self):
+        """Validation doesn't change the model's original values."""
+
+        cat = CategoryFactory.build()
+        budget = CategoryBudget(
+            category=cat,
+            amount_eur=150.75,
+            valid_from=date(2026, 9, 1),
+            valid_to=date(2026, 9, 30),
+        )
+
+        # Create an invalid one (valid_from > valid_to) and verify validation catches it
+        try:
+            CategoryBudget(
+                category=cat,
+                amount_eur=200.00,
+                valid_from=date(2026, 12, 31),
+                valid_to=date(2026, 12, 30),
+            )
+        except ValueError:
+            pass  # Expected
+
+        # Valid one should still have original values
+        assert budget.amount_eur == 150.75