Added first draft for test case on smoke read

tiled/_tests/test_client_smoke.py

@@ -0,0 +1,28 @@
+import collections
+
+import pytest
+
+from ..adapters.array import ArrayAdapter
+from ..adapters.mapping import MapAdapter
+from ..client import Context, from_context
+from ..client.smoke import read
+from ..server.app import build_app
+
+
+def f():
+    raise Exception("test!")
+
+
+def test_smoke_read():
+    data = collections.defaultdict(f)
+    data["A"] = ArrayAdapter.from_array([1, 2, 3], metadata={"A": "a"})
+
+    tree = MapAdapter(data)
+    with Context.from_app(build_app(tree)) as context:
+        client = from_context(context)
+
+    faulty_list = read(client)
+    assert len(faulty_list) == 1
+
+    with pytest.raises(Exception):
+        data["B"]