Documentation for Datasette() constructor, closes #1563

docs/internals.rst

@@ -196,6 +196,27 @@ Datasette class
 
 This object is an instance of the ``Datasette`` class, passed to many plugin hooks as an argument called ``datasette``.
 
+You can create your own instance of this - for example to help write tests for a plugin - like so:
+
+.. code-block:: python
+
+    from datasette.app import Datasette
+
+    # With no arguments a single in-memory database will be attached
+    datasette = Datasette()
+
+    # The files= argument can load files from disk
+    datasette = Datasette(files="/path/to/my-database.db")
+
+    # Pass metadata as a JSON dictionary like this
+    datasette = Datasette(files="/path/to/my-database.db", metadata={
+        "databases": {
+            "my-database": {
+                "description": "This is my database"
+            }
+        }
+    })
+
 .. _datasette_databases:
 
 .databases

tests/test_internals_datasette.py

@@ -50,7 +50,7 @@ def test_datasette_setting(datasette, setting, expected):
 
 @pytest.mark.asyncio
 async def test_datasette_constructor():
-    ds = Datasette(memory=True)
+    ds = Datasette()
     databases = (await ds.client.get("/-/databases.json")).json()
     assert databases == [
         {