Add tests for all but the content syntax parser module

tests/mocks/bad_graph/static/graph.toml

@@ -0,0 +1,3 @@
+[meta]
+config = {
+'

tests/mocks/good_json/graph.json

@@ -0,0 +1,13 @@
+{
+    "nodes": {
+        "JSON": {
+            "text": "",
+            "title": "JSON",
+            "links": [],
+            "id": "JSON",
+            "hidden": false,
+            "connections": []
+        }
+    },
+    "root_node": "JSON"
+}