Validate thing description in tests

tests/test_app.py

@@ -1,8 +1,13 @@
 from apispec.utils import validate_spec
+import json
+import jsonschema
+import os
+
 from openflexure_microscope.api.app import api_microscope, app, labthing
 from openflexure_microscope.camera.base import BaseCamera
 from openflexure_microscope.microscope import Microscope
 from openflexure_microscope.stage.base import BaseStage
+from labthings.json import encode_json
 
 
 def test_app_creation():
@@ -17,3 +22,24 @@ def test_microscope_creation():
 
 def test_openapi_valid():
     assert validate_spec(labthing.spec)
+
+def test_thing_description_valid():
+    # TODO: it would be nice to put this into LabThings
+    # First load the schema from file and check it validates
+    schema_fname = os.path.join(
+        os.path.dirname(__file__), 
+        "w3c_td_schema.json"
+    )
+    schema = json.load(open(schema_fname, "r"))
+    jsonschema.Draft7Validator.check_schema(schema)
+
+    # Build a TD dictionary
+    with labthing.app.test_request_context():
+            td_dict = labthing.thing_description.to_dict()
+
+    # Allow our LabThingsJSONEncoder to encode the RD
+    td_json = encode_json(td_dict)
+    # Decode the JSON back into a primitive dictionary
+    td_json_dict = json.loads(td_json)
+    # Validate
+    jsonschema.validate(instance=td_json_dict, schema=schema)