New spatialite helper methods, closes #79

- db.init_spatialite()
- table.add_geometry_column()
- table.create_spatial_index()

Co-authored-by: Simon Willison <swillison@gmail.com>

tests/test_gis.py

@@ -0,0 +1,83 @@
+import pytest
+from sqlite_utils.utils import find_spatialite
+from sqlite_utils.db import Database
+from sqlite_utils.utils import sqlite3
+
+pytestmark = [
+    pytest.mark.skipif(
+        not find_spatialite(), reason="Could not find SpatiaLite extension"
+    ),
+    pytest.mark.skipif(
+        not hasattr(sqlite3.Connection, "enable_load_extension"),
+        reason="sqlite3.Connection missing enable_load_extension",
+    ),
+]
+
+
+def test_find_spatialite():
+    spatialite = find_spatialite()
+    assert spatialite is None or isinstance(spatialite, str)
+
+
+def test_init_spatialite():
+    db = Database(memory=True)
+    spatialite = find_spatialite()
+    db.init_spatialite(spatialite)
+    assert "spatial_ref_sys" in db.table_names()
+
+
+def test_add_geometry_column():
+    db = Database(memory=True)
+    spatialite = find_spatialite()
+    db.init_spatialite(spatialite)
+
+    # create a table first
+    table = db.create_table("locations", {"id": str, "properties": str})
+    table.add_geometry_column(
+        column_name="geometry",
+        geometry_type="Point",
+        srid=4326,
+        coord_dimension=2,
+    )
+
+    assert db["geometry_columns"].get(["locations", "geometry"]) == {
+        "f_table_name": "locations",
+        "f_geometry_column": "geometry",
+        "geometry_type": 1,  # point
+        "coord_dimension": 2,
+        "srid": 4326,
+        "spatial_index_enabled": 0,
+    }
+
+
+def test_create_spatial_index():
+    db = Database(memory=True)
+    spatialite = find_spatialite()
+    assert db.init_spatialite(spatialite)
+
+    # create a table, add a geometry column with default values
+    table = db.create_table("locations", {"id": str, "properties": str})
+    assert table.add_geometry_column("geometry", "Point")
+
+    # index it
+    assert table.create_spatial_index("geometry")
+
+    assert "idx_locations_geometry" in db.table_names()
+
+
+def test_double_create_spatial_index():
+    db = Database(memory=True)
+    spatialite = find_spatialite()
+    db.init_spatialite(spatialite)
+
+    # create a table, add a geometry column with default values
+    table = db.create_table("locations", {"id": str, "properties": str})
+    table.add_geometry_column("geometry", "Point")
+
+    # index it, return True
+    assert table.create_spatial_index("geometry")
+
+    assert "idx_locations_geometry" in db.table_names()
+
+    # call it again, return False
+    assert not table.create_spatial_index("geometry")

tests/test_utils.py

@@ -22,11 +22,6 @@ def test_decode_base64_values(input, expected, should_be_is):
         assert actual == expected
 
 
-def test_find_spatialite():
-    spatialite = utils.find_spatialite()
-    assert spatialite is None or isinstance(spatialite, str)
-
-
 @pytest.mark.parametrize(
     "size,expected",
     (