Added tests for index class.

test/test_dbcore.py

@@ -23,7 +23,7 @@ from tempfile import mkstemp
 import pytest
 
 from beets import dbcore
-from beets.dbcore.db import DBCustomFunctionError
+from beets.dbcore.db import DBCustomFunctionError, Index
 from beets.library import LibModel
 from beets.test import _common
 from beets.util import cached_classproperty
@@ -66,6 +66,7 @@ class ModelFixture1(LibModel):
     _sorts = {
         "some_sort": SortFixture,
     }
+    _indices = (Index("field_one_index", ("field_one",)),)
 
     @cached_classproperty
     def _types(cls):
@@ -137,6 +138,7 @@ class AnotherModelFixture(ModelFixture1):
         "id": dbcore.types.PRIMARY_ID,
         "foo": dbcore.types.INTEGER,
     }
+    _indices = (Index("another_foo_index", ("foo",)),)
 
 
 class ModelFixture5(ModelFixture1):
@@ -808,3 +810,71 @@ class TestException:
         with pytest.raises(DBCustomFunctionError):
             with db.transaction() as tx:
                 tx.query("select * from test where plz_raise()")
+
+                
+class TestIndex:
+    @pytest.fixture(autouse=True)
+    def db(self):
+        """Set up an in-memory SQLite database."""
+        db = DatabaseFixture1(":memory:")
+        yield db
+        db._connection().close()
+
+    @pytest.fixture
+    def sample_index(self):
+        """Fixture for a sample Index object."""
+        return Index(name="sample_index", columns=("field_one",))
+
+    def test_from_db(self, db, sample_index: Index):
+        """Test retrieving an index from the database."""
+        with db.transaction() as tx:
+            sample_index.recreate(tx, "test")
+            retrieved = Index.from_db(tx, sample_index.name)
+            assert retrieved == sample_index
+
+    @pytest.mark.parametrize(
+        "index1, index2, equality",
+        [
+            (
+                # Same
+                Index(name="sample_index", columns=("field_one",)),
+                Index(name="sample_index", columns=("field_one",)),
+                True,
+            ),
+            (
+                # Multiple columns
+                Index(name="sample_index", columns=("f1", "f2")),
+                Index(name="sample_index", columns=("f1", "f2")),
+                True,
+            ),
+            (
+                # Difference in name
+                Index(name="sample_indey", columns=("field_one",)),
+                Index(name="sample_index", columns=("field_one",)),
+                False,
+            ),
+            (
+                # Difference in columns
+                Index(name="sample_indey", columns=("field_one",)),
+                Index(name="sample_index", columns=("field_two",)),
+                False,
+            ),
+            (
+                # Difference in num columns
+                Index(name="sample_index", columns=("f1",)),
+                Index(name="sample_index", columns=("f1", "f2")),
+                False,
+            ),
+        ],
+    )
+    def test_index_equality(self, index1: Index, index2: Index, equality: bool):
+        """Test the hashing and set behavior of the Index class."""
+
+        # Simple equality
+        assert (index1 == index2) == equality
+
+        # Should be unique or not
+        index_set = {index1, index2}
+        assert len(index_set) == (1 if equality else 2)
+
+