Added datasette.get_database() method

Refs #576

tests/test_database.py

@@ -1,3 +1,6 @@
+"""
+Tests for the datasette.database.Database class
+"""
 from datasette.database import Results, MultipleValues
 from datasette.utils import sqlite3
 from .fixtures import app_client

tests/test_internals_datasette.py

@@ -0,0 +1,23 @@
+"""
+Tests for the datasette.app.Datasette class
+"""
+from .fixtures import app_client
+import pytest
+
+
+@pytest.fixture
+def datasette(app_client):
+    return app_client.ds
+
+
+def test_get_database(datasette):
+    db = datasette.get_database("fixtures")
+    assert "fixtures" == db.name
+    with pytest.raises(KeyError):
+        datasette.get_database("missing")
+
+
+def test_get_database_no_argument(datasette):
+    # Returns the first available database:
+    db = datasette.get_database()
+    assert "fixtures" == db.name