Add failing tests

test/invalid-instances/empty.json

+{}

test/test-failure.yml

+- name: test-missing_readgroup
+  command: jsonschema -i test/invalid-instances/missing_readgroup.json transfer_schema.json
+  exit_code: 1
+
+- name: test-emtpy-file
+  command: jsonschema -i test/invalid-instances/empty.json transfer_schema.json
+  exit_code: 1
+  stderr:
+    contains:
+      - "'title' is a required property"
+      - "'sample_group' is a required property"
+      - "'run_name' is a required property"
+      - "'files' is a required property"

test/test-schema.yml

-- name: test-missing_readgroup
-  command: jsonschema -i transfer_schema.json test/instances/missing_readgroup.json 
-  exit_code: 1
-