db.sqlite_version property and fix for deterministic=True on SQLite 3.8.3

Closes #408

Author: simonw

docs/python-api.rst

@@ -1717,6 +1717,16 @@ A more useful example: if you are working with `SpatiaLite <https://www.gaia-gis
 
 This example uses gographical data from [Who's On First](https://whosonfirst.org/) and depends on the [Shapely](https://shapely.readthedocs.io/en/stable/manual.html) and [HTTPX](https://www.python-httpx.org/) Python libraries.
 
+.. _python_api_sqlite_version:
+
+Checking the SQLite version
+===========================
+
+The ``db.sqlite_version`` property returns a tuple of integers representing the version of SQLite used for that database object::
+
+    >>> db.sqlite_version
+    (3, 36, 0)
+
 .. _python_api_introspection:
 
 Introspecting tables and views

sqlite_utils/db.py

@@ -387,7 +387,11 @@ def register(fn):
             if not replace and (name, arity) in self._registered_functions:
                 return fn
             kwargs = {}
-            if deterministic and sys.version_info >= (3, 8):
+            if (
+                deterministic
+                and sys.version_info >= (3, 8)
+                and self.sqlite_version >= (3, 8, 3)
+            ):
                 kwargs["deterministic"] = True
             self.conn.create_function(name, arity, fn, **kwargs)
             self._registered_functions.add((name, arity))
@@ -547,6 +551,12 @@ def supports_strict(self) -> bool:
         except Exception:
             return False
 
+    @property
+    def sqlite_version(self) -> Tuple[int, ...]:
+        "Version of SQLite, as a tuple of integers e.g. (3, 36, 0)"
+        row = self.execute("select sqlite_version()").fetchall()[0]
+        return tuple(map(int, row[0].split(".")))
+
     @property
     def journal_mode(self) -> str:
         "Current ``journal_mode`` of this database."

tests/test_constructor.py

@@ -16,3 +16,12 @@ def test_memory_name():
     db2 = Database(memory_name="shared")
     db1["dogs"].insert({"name": "Cleo"})
     assert list(db2["dogs"].rows) == [{"name": "Cleo"}]
+
+
+def test_sqlite_version():
+    db = Database(memory=True)
+    version = db.sqlite_version
+    assert isinstance(version, tuple)
+    as_string = ".".join(map(str, version))
+    actual = next(db.query("select sqlite_version() as v"))["v"]
+    assert actual == as_string

tests/test_register_function.py

@@ -34,16 +34,31 @@ def to_lower(s):
 @pytest.mark.skipif(
     sys.version_info < (3, 8), reason="deterministic=True was added in Python 3.8"
 )
-def test_register_function_deterministic_registered(fresh_db):
+@pytest.mark.parametrize(
+    "fake_sqlite_version,should_use_deterministic",
+    (
+        ("3.36.0", True),
+        ("3.8.3", True),
+        ("3.8.2", False),
+    ),
+)
+def test_register_function_deterministic_registered(
+    fresh_db, fake_sqlite_version, should_use_deterministic
+):
     fresh_db.conn = MagicMock()
     fresh_db.conn.create_function = MagicMock()
+    fresh_db.conn.execute().fetchall.return_value = [(fake_sqlite_version,)]
 
     @fresh_db.register_function(deterministic=True)
     def to_lower_2(s):
         return s.lower()
 
+    expected_kwargs = {}
+    if should_use_deterministic:
+        expected_kwargs = dict(deterministic=True)
+
     fresh_db.conn.create_function.assert_called_with(
-        "to_lower_2", 1, to_lower_2, deterministic=True
+        "to_lower_2", 1, to_lower_2, **expected_kwargs
     )