{
    "graph": {
      "metadata": {
        "number_of_nodes": 2,
        "number_of_links": 1
      },
      "nodes": [
        {
          "id": "0",
          "metadata": {
            "node_squared_radius": 9,
            "node_coordinates": {
              "x": 0,
              "y": 0,
              "z": 0
            }
          }
        },
        {
          "id": "1",
          "metadata": {
            "node_squared_radius": 4,
            "node_coordinates": {
              "x": 1,
              "y": 1,
              "z": 1
            }
          }
        }
      ],
      "edges": [
        {
          "id": "0",
          "source": "0",
          "target": "1",
          "metadata": {
            "link_length": 1.73205080757,
            "link_squared_radius": 5.169298742047715
          }
        }
      ]
    }
  }
  
Add basic JSON fixture for `JSONGraphFormatTest`
Add basic JSON fixture for `JSONGraphFormatTest`
