New handle_exception plugin hook, refs #1770

Also refs:
- https://github.com/simonw/datasette-sentry/issues/1
- https://github.com/simonw/datasette-show-errors/issues/2

tests/fixtures.py

@@ -68,6 +68,7 @@ EXPECTED_PLUGINS = [
             "canned_queries",
             "extra_js_urls",
             "extra_template_vars",
+            "handle_exception",
             "menu_links",
             "permission_allowed",
             "register_routes",

tests/plugins/my_plugin_2.py

@@ -185,3 +185,21 @@ def register_routes(datasette):
         # Also serves to demonstrate over-ride of default paths:
         (r"/(?P<db_name>[^/]+)/(?P<table_and_format>[^/]+?$)", new_table),
     ]
+
+
+@hookimpl
+def handle_exception(datasette, request, exception):
+    datasette._exception_hook_fired = (request, exception)
+    if request.args.get("_custom_error"):
+        return Response.text("_custom_error")
+    elif request.args.get("_custom_error_async"):
+
+        async def inner():
+            return Response.text("_custom_error_async")
+
+        return inner
+
+
+@hookimpl(specname="register_routes")
+def register_triger_error():
+    return ((r"/trigger-error", lambda: 1 / 0),)

tests/test_permissions.py

@@ -332,6 +332,7 @@ def test_permissions_debug(app_client):
     assert checks == [
         {"action": "permissions-debug", "result": True, "used_default": False},
         {"action": "view-instance", "result": None, "used_default": True},
+        {"action": "debug-menu", "result": False, "used_default": True},
         {"action": "permissions-debug", "result": False, "used_default": True},
         {"action": "view-instance", "result": None, "used_default": True},
     ]

tests/test_plugins.py

@@ -824,6 +824,20 @@ def test_hook_forbidden(restore_working_directory):
         assert "view-database" == client.ds._last_forbidden_message
 
 
+def test_hook_handle_exception(app_client):
+    app_client.get("/trigger-error?x=123")
+    assert hasattr(app_client.ds, "_exception_hook_fired")
+    request, exception = app_client.ds._exception_hook_fired
+    assert request.url == "http://localhost/trigger-error?x=123"
+    assert isinstance(exception, ZeroDivisionError)
+
+
+@pytest.mark.parametrize("param", ("_custom_error", "_custom_error_async"))
+def test_hook_handle_exception_custom_response(app_client, param):
+    response = app_client.get("/trigger-error?{}=1".format(param))
+    assert response.text == param
+
+
 def test_hook_menu_links(app_client):
     def get_menu_links(html):
         soup = Soup(html, "html.parser")