First working -d based Datasette Library

Refs #417

First proof-of-concept for Datasette Library. Run like this:

    datasette -d ~/Library

Uses a new plugin hook - available_databases()

BUT... I don't think this is quite the way I want to go.

tests/fixtures.py

@@ -321,6 +321,8 @@ METADATA = {
 
 PLUGIN1 = """
 from datasette import hookimpl
+from datasette.database import Database
+from datasette.utils import sqlite3
 import base64
 import pint
 import json
@@ -397,6 +399,20 @@ def extra_template_vars(template, database, table, view_name, request, datasette
             "extra_serve_options": datasette.extra_serve_options,
         }, default=lambda b: b.decode("utf8"))
     }
+
+
+class SpecialDatabase(Database):
+    def connect(self):
+        db = sqlite3.connect(":memory:")
+        db.executescript("CREATE TABLE foo (id integer primary key, bar text)")
+        db.executescript("INSERT INTO foo (id, bar) VALUES (1, 'hello')")
+        return db
+
+@hookimpl
+def available_databases(datasette):
+    return [
+        ("special", SpecialDatabase(datasette, name="special")),
+    ]
 """
 
 PLUGIN2 = """

tests/test_api.py

@@ -24,7 +24,7 @@ def test_homepage(app_client):
     response = app_client.get("/.json")
     assert response.status == 200
     assert "application/json; charset=utf-8" == response.headers["content-type"]
-    assert response.json.keys() == {"fixtures": 0}.keys()
+    assert {"fixtures", "special"} == set(response.json.keys())
     d = response.json["fixtures"]
     assert d["name"] == "fixtures"
     assert d["tables_count"] == 24
@@ -518,19 +518,45 @@ def test_no_files_uses_memory_database(app_client_no_files):
     assert response.status == 200
     assert {
         ":memory:": {
+            "name": ":memory:",
             "hash": None,
+            "comment": None,
             "color": "f7935d",
+            "path": "/:memory:",
+            "tables_and_views_truncated": [],
+            "tables_and_views_more": False,
+            "tables_count": 0,
+            "table_rows_sum": 0,
+            "show_table_row_counts": False,
             "hidden_table_rows_sum": 0,
             "hidden_tables_count": 0,
-            "name": ":memory:",
-            "show_table_row_counts": False,
-            "path": "/:memory:",
-            "table_rows_sum": 0,
-            "tables_count": 0,
-            "tables_and_views_more": False,
-            "tables_and_views_truncated": [],
             "views_count": 0,
-        }
+        },
+        "special": {
+            "name": "special",
+            "hash": None,
+            "comment": None,
+            "color": "0bd650",
+            "path": "/special",
+            "tables_and_views_truncated": [
+                {
+                    "name": "foo",
+                    "columns": ["id", "bar"],
+                    "primary_keys": ["id"],
+                    "count": 1,
+                    "hidden": False,
+                    "fts_table": None,
+                    "num_relationships_for_sorting": 0,
+                }
+            ],
+            "tables_and_views_more": False,
+            "tables_count": 1,
+            "table_rows_sum": 1,
+            "show_table_row_counts": True,
+            "hidden_table_rows_sum": 0,
+            "hidden_tables_count": 0,
+            "views_count": 0,
+        },
     } == response.json
     # Try that SQL query
     response = app_client_no_files.get(
@@ -1170,8 +1196,10 @@ def test_unit_filters(app_client):
 def test_databases_json(app_client_two_attached_databases_one_immutable):
     response = app_client_two_attached_databases_one_immutable.get("/-/databases.json")
     databases = response.json
-    assert 2 == len(databases)
-    extra_database, fixtures_database = databases
+    assert 3 == len(databases)
+    by_name = {database["name"]: database for database in databases}
+    extra_database = by_name["extra_database"]
+    fixtures_database = by_name["fixtures"]
     assert "extra_database" == extra_database["name"]
     assert None == extra_database["hash"]
     assert True == extra_database["is_mutable"]

tests/test_cli.py

@@ -9,7 +9,6 @@ def test_inspect_cli(app_client):
     runner = CliRunner()
     result = runner.invoke(cli, ["inspect", "fixtures.db"])
     data = json.loads(result.output)
-    assert ["fixtures"] == list(data.keys())
     database = data["fixtures"]
     assert "fixtures.db" == database["file"]
     assert isinstance(database["hash"], str)
@@ -28,7 +27,7 @@ def test_inspect_cli_writes_to_file(app_client):
     )
     assert 0 == result.exit_code, result.output
     data = json.load(open("foo.json"))
-    assert ["fixtures"] == list(data.keys())
+    assert {"fixtures", "special"} == set(data.keys())
 
 
 def test_serve_with_inspect_file_prepopulates_table_counts_cache():

tests/test_html.py

@@ -28,6 +28,7 @@ def test_homepage(app_client_two_attached_databases):
     assert [
         {"href": "/extra_database", "text": "extra_database"},
         {"href": "/fixtures", "text": "fixtures"},
+        {"href": "/special", "text": "special"},
     ] == [{"href": a["href"], "text": a.text.strip()} for a in soup.select("h2 a")]
     # The first attached database should show count text and attached tables
     h2 = soup.select("h2")[0]

tests/test_plugins.py

@@ -188,7 +188,7 @@ def test_plugins_extra_body_script(app_client, path, expected_extra_body_script)
 
 def test_plugins_asgi_wrapper(app_client):
     response = app_client.get("/fixtures")
-    assert "fixtures" == response.headers["x-databases"]
+    assert "fixtures, special" == response.headers["x-databases"]
 
 
 def test_plugins_extra_template_vars(restore_working_directory):
@@ -228,3 +228,19 @@ def test_extra_serve_options_available_on_datasette(restore_working_directory):
             Soup(response.body, "html.parser").select("pre.extra_template_vars")[0].text
         )
         assert {"foo": "bar"} == extra_template_vars["extra_serve_options"]
+
+
+def test_plugins_available_databases(app_client):
+    response = app_client.get("/-/databases.json")
+    assert 200 == response.status
+    assert {
+        "name": "special",
+        "path": None,
+        "size": 0,
+        "is_mutable": False,
+        "is_memory": False,
+        "hash": None,
+    } in response.json
+    assert [{"id": 1, "bar": "hello"}] == app_client.get(
+        "/special/foo.json?_shape=array"
+    ).json