extracts= table parameter, closes #46

tests/test_extracts.py

@@ -0,0 +1,63 @@
+from sqlite_utils.db import Index
+import pytest
+
+
+@pytest.mark.parametrize(
+    "kwargs,expected_table",
+    [
+        (dict(extracts={"species_id": "Species"}), "Species"),
+        (dict(extracts=["species_id"]), "species_id"),
+        (dict(extracts=("species_id",)), "species_id"),
+    ],
+)
+@pytest.mark.parametrize("use_table_factory", [True, False])
+def test_extracts(fresh_db, kwargs, expected_table, use_table_factory):
+    table_kwargs = {}
+    insert_kwargs = {}
+    if use_table_factory:
+        table_kwargs = kwargs
+    else:
+        insert_kwargs = kwargs
+    trees = fresh_db.table("Trees", **table_kwargs)
+    trees.insert_all(
+        [
+            {"id": 1, "species_id": "Oak"},
+            {"id": 2, "species_id": "Oak"},
+            {"id": 3, "species_id": "Palm"},
+        ],
+        **insert_kwargs
+    )
+    # Should now have two tables: Trees and Species
+    assert {expected_table, "Trees"} == set(fresh_db.table_names())
+    assert (
+        "CREATE TABLE [{}] (\n   [id] INTEGER PRIMARY KEY,\n   [value] TEXT\n)".format(
+            expected_table
+        )
+        == fresh_db[expected_table].schema
+    )
+    assert (
+        "CREATE TABLE [Trees] (\n   [id] INTEGER,\n   [species_id] INTEGER REFERENCES [{}]([id])\n)".format(
+            expected_table
+        )
+        == fresh_db["Trees"].schema
+    )
+    # Should have unique index on Species
+    assert [
+        Index(
+            seq=0,
+            name="idx_{}_value".format(expected_table),
+            unique=1,
+            origin="c",
+            partial=0,
+            columns=["value"],
+        )
+    ] == fresh_db[expected_table].indexes
+    # Finally, check the rows
+    assert [{"id": 1, "value": "Oak"}, {"id": 2, "value": "Palm"}] == list(
+        fresh_db[expected_table].rows
+    )
+    assert [
+        {"id": 1, "species_id": 1},
+        {"id": 2, "species_id": 1},
+        {"id": 3, "species_id": 2},
+    ] == list(fresh_db["Trees"].rows)