Fix dashboard exploration when the annotations.list slot is None

The expected value would have been an empty list instead. This patch
makes the gathering process more graceful.

Author: amotl

CHANGES.rst

@@ -6,6 +6,8 @@ grafana-wtf changelog
 in progress
 ===========
 - CI: Use most recent Grafana 7.5.16, 8.5.5, and 9.0.0-beta3
+- Fix dashboard exploration when the ``annotations.list`` slot is ``None``
+  instead of an empty list. Thanks, @TaylorMutch!
 
 2022-03-25 0.13.3
 =================

grafana_wtf/core.py

@@ -497,6 +497,7 @@ def index(self):
 
     @staticmethod
     def collect_datasource_items(element):
+        element = element or []
         items = []
         for node in element:
             if "datasource" in node and node["datasource"]:

tests/conftest.py

@@ -3,7 +3,7 @@
 import re
 from io import StringIO
 from pathlib import Path
-from typing import List, Union
+from typing import List, Union, Optional
 
 import grafanalib.core
 import pytest
@@ -321,12 +321,14 @@ def grafana_version(docker_grafana):
     return grafana_version
 
 
-def mkdashboard(title: str, datasources: List[str]):
+def mkdashboard(title: str, datasources: Optional[List[str]] = None):
     """
     Build dashboard with multiple panels, each with a different data source.
     """
     # datasource = grafanalib.core.DataSourceInput(name="foo", label="foo", pluginId="foo", pluginName="foo")
 
+    datasources = datasources or []
+
     # Build dashboard object model.
     panels = []
     for datasource in datasources:

tests/test_commands.py

@@ -366,6 +366,33 @@ def test_explore_dashboards_grafana7up(grafana_version, ldi_resources, capsys, c
     assert dashboard["datasources_missing"][0]["type"] is None
 
 
+def test_explore_dashboards_empty_annotations(create_datasource, create_dashboard, capsys, caplog):
+
+    # Create a dashboard with an anomalous value in the "annotations" slot.
+    dashboard = mkdashboard(title="foo")
+    dashboard["annotations"]["list"] = None
+    create_dashboard(dashboard)
+
+    # Compute breakdown.
+    set_command("explore dashboards", "--format=yaml")
+
+    # Proof the output is correct.
+    with caplog.at_level(logging.DEBUG):
+        grafana_wtf.commands.run()
+        assert "Found 1 dashboard(s)" in caplog.messages
+
+    captured = capsys.readouterr()
+    data = yaml.safe_load(captured.out)
+
+    # Proof the output is correct.
+    assert len(data) == 1
+    dashboard = data[0]
+    assert dashboard["dashboard"]["title"] == "foo"
+    assert len(dashboard["dashboard"]["uid"]) == 9
+    assert "datasources" not in dashboard
+    assert "datasources_missing" not in dashboard
+
+
 def find_all_missing_datasources(data):
     missing_items = []
     for item in data: