add a test for instance

tests/cassettes/test_instance.yaml

@@ -0,0 +1,27 @@
+interactions:
+- request:
+    body: null
+    headers:
+      Accept: ['*/*']
+      Accept-Encoding: ['gzip, deflate']
+      Authorization: [Bearer __MASTODON_PY_TEST_TOKEN]
+      Connection: [keep-alive]
+      User-Agent: [python-requests/2.18.4]
+    method: GET
+    uri: http://localhost:3000/api/v1/instance/
+  response:
+    body: {string: '{"uri":"localhost:3000","title":"Mastodon","description":"","email":"","version":"2.0.0","urls":{"streaming_api":"ws://localhost:4000"},"stats":{"user_count":2,"status_count":22,"domain_count":1},"thumbnail":null}'}
+    headers:
+      Cache-Control: ['max-age=0, private, must-revalidate']
+      Content-Type: [application/json; charset=utf-8]
+      ETag: [W/"c5c80940c21c432b7b5c69bcf67a8ff3"]
+      Transfer-Encoding: [chunked]
+      Vary: ['Accept-Encoding, Origin']
+      X-Content-Type-Options: [nosniff]
+      X-Frame-Options: [SAMEORIGIN]
+      X-Request-Id: [23b994ca-448c-42a7-a107-c39e58742541]
+      X-Runtime: ['0.046093']
+      X-XSS-Protection: [1; mode=block]
+      content-length: ['213']
+    status: {code: 200, message: OK}
+version: 1

tests/test_instance.py

@@ -0,0 +1,11 @@
+from .fixtures import *
+import pytest
+
+@pytest.mark.vcr()
+def test_instance(mastodon):
+    instance = mastodon.instance()
+
+    assert isinstance(instance, dict)  # hehe, instance is instance
+
+    expected_keys = set(('description', 'email', 'title', 'uri', 'version', 'urls'))
+    assert set(instance.keys()) >= expected_keys