From 4d798ca0e3df246bd47f0600cc7b5118ba33ac16 Mon Sep 17 00:00:00 2001
From: Simon Willison <swillison@gmail.com>
Date: Sat, 30 May 2020 11:17:20 -0700
Subject: [PATCH] Added test for db.mtime_ns

---
 datasette/database.py            |  4 +++-
 tests/test_internals_database.py | 12 +++++++++++-
 2 files changed, 14 insertions(+), 2 deletions(-)

diff --git a/datasette/database.py b/datasette/database.py
index 89bf47f4..ed119542 100644
--- a/datasette/database.py
+++ b/datasette/database.py
@@ -33,7 +33,7 @@ class Database:
         self.cached_table_counts = None
         self._write_thread = None
         self._write_queue = None
-        if not self.is_mutable:
+        if not self.is_mutable and not self.is_memory:
             p = Path(path)
             self.hash = inspect_hash(p)
             self.cached_size = p.stat().st_size
@@ -197,6 +197,8 @@ class Database:
 
     @property
     def mtime_ns(self):
+        if self.is_memory:
+            return None
         return Path(self.path).stat().st_mtime_ns
 
     @property
diff --git a/tests/test_internals_database.py b/tests/test_internals_database.py
index fde7ad2c..5d5520dd 100644
--- a/tests/test_internals_database.py
+++ b/tests/test_internals_database.py
@@ -1,7 +1,7 @@
 """
 Tests for the datasette.database.Database class
 """
-from datasette.database import Results, MultipleValues
+from datasette.database import Database, Results, MultipleValues
 from datasette.utils import sqlite3
 from .fixtures import app_client
 import pytest
@@ -188,3 +188,13 @@ async def test_execute_write_fn_exception(db):
 
     with pytest.raises(AssertionError):
         await db.execute_write_fn(write_fn, block=True)
+
+
+@pytest.mark.asyncio
+async def test_mtime_ns(db):
+    assert isinstance(db.mtime_ns, int)
+
+
+def test_mtime_ns_is_none_for_memory(app_client):
+    memory_db = Database(app_client.ds, is_memory=True)
+    assert None is memory_db.mtime_ns