Add reproducing yaml test

Author: jordan-powers

x-pack/plugin/downsample/qa/rest/src/yamlRestTest/resources/rest-api-spec/test/downsample/80_re_downsample.yml

@@ -0,0 +1,70 @@
+"Downsample index":
+  - requires:
+      cluster_features: ["gte_v8.13.0"]
+      reason: _tsid hashing introduced in 8.13
+
+  - do:
+      indices.create:
+        index: test
+        body:
+          settings:
+            number_of_shards: 1
+            index:
+              mode: time_series
+              routing_path: [sensor_id]
+              time_series:
+                start_time: 2021-04-28T00:00:00Z
+                end_time: 2021-04-29T00:00:00Z
+          mappings:
+            properties:
+              "@timestamp":
+                type: date
+              sensor_id:
+                type: keyword
+                time_series_dimension: true
+              temperature:
+                type: aggregate_metric_double
+                metrics: [min, sum, value_count]
+                default_metric: sum
+                time_series_metric: gauge
+  - do:
+      bulk:
+        refresh: true
+        index: test
+        body:
+          - '{"index": {}}'
+          - '{"@timestamp": "2021-04-28T18:00:0.000Z", "sensor_id": "1", "temperature": {"min": 24.7, "sum": 50.2, "value_count": 2}}'
+          - '{"index": {}}'
+          - '{"@timestamp": "2021-04-28T18:30:0.000Z", "sensor_id": "1", "temperature": {"min": 24.2, "sum": 73.8, "value_count": 3}}'
+          - '{"index": {}}'
+          - '{"@timestamp": "2021-04-28T19:00:0.000Z", "sensor_id": "1", "temperature": {"min": 25.1, "sum": 51.0, "value_count": 2}}'
+          - '{"index": {}}'
+          - '{"@timestamp": "2021-04-28T19:30:0.000Z", "sensor_id": "1", "temperature": {"min": 24.8, "sum": 24.8, "value_count": 1}}'
+          - '{"index": {}}'
+          - '{"@timestamp": "2021-04-28T20:00:0.000Z", "sensor_id": "1", "temperature": {"min": 24.6, "sum": 49.1, "value_count": 2}}'
+
+  - do:
+      indices.put_settings:
+        index: test
+        body:
+          index.blocks.write: true
+
+  - do:
+      indices.downsample:
+        index: test
+        target_index: test-downsample
+        body:  >
+          {
+            "fixed_interval": "1h"
+          }
+  - is_true: acknowledged
+
+  - do:
+      indices.get_mapping:
+        index: test-downsample
+  - match:
+      test-downsample.mappings.properties.temperature:
+        type: aggregate_metric_double
+        metrics: [min, sum, value_count]
+        default_metric: sum
+        time_series_metric: gauge