Fix validation of begin/end in GET /v2/summary endpoint

Before this patch, if any of the "begin" and "end" parameters
were passed to the GET /v2/summary endpoint, validation would fail.

This was caused by "voluptuous.Coerce" being used instead of the
custom "SingleQueryParam" validator.

Change-Id: I09656c742f3ba6b02de3656201f6903f590944bd

cloudkitty/api/v2/summary/summary.py

@@ -29,8 +29,10 @@ class Summary(base.BaseResource):
         voluptuous.Optional('groupby'): api_utils.MultiQueryParam(str),
         voluptuous.Optional('filters'):
             api_utils.SingleDictQueryParam(str, str),
-        voluptuous.Optional('begin'): voluptuous.Coerce(tzutils.dt_from_iso),
-        voluptuous.Optional('end'): voluptuous.Coerce(tzutils.dt_from_iso),
+        voluptuous.Optional('begin'): api_utils.SingleQueryParam(
+            tzutils.dt_from_iso),
+        voluptuous.Optional('end'): api_utils.SingleQueryParam(
+            tzutils.dt_from_iso),
     })
     def get(self, groupby=None, filters={},
             begin=None, end=None,

cloudkitty/tests/gabbi/gabbits/v2-summary.yaml

@@ -58,3 +58,13 @@ tests:
     response_json_paths:
       $.results.`len`: 5
       $.total: 14
+
+  - name: Get a summary with a start and end date
+    url: /v2/summary
+    status: 200
+    query_parameters:
+      begin: "2017-01-01T00:00:00+00:00"
+      end: "2017-01-02T00:00:00+00:00"
+    response_json_paths:
+      $.results.`len`: 0
+      $.total: 0

releasenotes/notes/fix-begin-end-validation-v2-summary-52401fb47ef9b5d6.yaml

@@ -0,0 +1,6 @@
+---
+fixes:
+  - |
+    A validation issue causing the ``GET /v2/summary`` endpoint to
+    systematically return a 400 error if any of the ``begin`` or ``end``
+    parameters was specified has been fixed.