From cfad77d3571aec69b43bef6c73be47e101aee3c5 Mon Sep 17 00:00:00 2001
From: Wylie Conlon <wylieconlon@gmail.com>
Date: Thu, 11 Feb 2021 13:54:58 -0500
Subject: [PATCH] Add test for edge case

---
 .../plugins/lens/server/routes/field_stats.ts |  7 +++-
 .../api_integration/apis/lens/field_stats.ts  | 34 ++++++++++++++++---
 .../apps/visualize/precalculated_histogram.ts |  4 +--
 .../pre_calculated_histogram/data.json        | 21 +++++++++++-
 4 files changed, 57 insertions(+), 9 deletions(-)

diff --git a/x-pack/plugins/lens/server/routes/field_stats.ts b/x-pack/plugins/lens/server/routes/field_stats.ts
index b7e4f8223757a1..7fd884755d86df 100644
--- a/x-pack/plugins/lens/server/routes/field_stats.ts
+++ b/x-pack/plugins/lens/server/routes/field_stats.ts
@@ -187,7 +187,12 @@ export async function getNumberHistogram(
       sampledValues: minMaxResult.aggregations!.sample.sample_count.value!,
       sampledDocuments: minMaxResult.aggregations!.sample.doc_count,
       topValues: topValuesBuckets,
-      histogram: { buckets: [] },
+      histogram: useTopHits
+        ? { buckets: [] }
+        : {
+            // Insert a fake bucket for a single-value histogram
+            buckets: [{ count: minMaxResult.aggregations!.sample.doc_count, key: minValue }],
+          },
     };
   }
 
diff --git a/x-pack/test/api_integration/apis/lens/field_stats.ts b/x-pack/test/api_integration/apis/lens/field_stats.ts
index e715d765d93496..ac4ebb4e5b02c2 100644
--- a/x-pack/test/api_integration/apis/lens/field_stats.ts
+++ b/x-pack/test/api_integration/apis/lens/field_stats.ts
@@ -376,7 +376,7 @@ export default ({ getService }: FtrProviderContext) => {
                 key: 0.47000000000000003,
               },
               {
-                count: 556,
+                count: 454,
                 key: 0.9400000000000001,
               },
               {
@@ -396,7 +396,7 @@ export default ({ getService }: FtrProviderContext) => {
                 key: 2.8200000000000003,
               },
               {
-                count: 596,
+                count: 391,
                 key: 3.29,
               },
               {
@@ -408,15 +408,39 @@ export default ({ getService }: FtrProviderContext) => {
                 key: 4.23,
               },
               {
-                count: 639,
+                count: 628,
                 key: 4.7,
               },
             ],
           },
           sampledDocuments: 7,
-          sampledValues: 4151,
+          sampledValues: 3833,
           totalDocuments: 7,
-          topValues: [],
+          topValues: { buckets: [] },
+        });
+      });
+
+      it('should return a single-value histogram when filtering a precalculated histogram', async () => {
+        const { body } = await supertest
+          .post('/api/lens/index_stats/histogram-test/field')
+          .set(COMMON_HEADERS)
+          .send({
+            dslQuery: { match: { 'histogram-title': 'single value' } },
+            fromDate: TEST_START_TIME,
+            toDate: TEST_END_TIME,
+            field: {
+              name: 'histogram-content',
+              type: 'histogram',
+            },
+          })
+          .expect(200);
+
+        expect(body).to.eql({
+          histogram: { buckets: [{ count: 1, key: 1 }] },
+          sampledDocuments: 1,
+          sampledValues: 1,
+          totalDocuments: 1,
+          topValues: { buckets: [] },
         });
       });
 
diff --git a/x-pack/test/functional/apps/visualize/precalculated_histogram.ts b/x-pack/test/functional/apps/visualize/precalculated_histogram.ts
index a0c8fa3b21ffd2..151c9e981250f9 100644
--- a/x-pack/test/functional/apps/visualize/precalculated_histogram.ts
+++ b/x-pack/test/functional/apps/visualize/precalculated_histogram.ts
@@ -64,7 +64,7 @@ export default function ({ getService, getPageObjects }: FtrProviderContext) {
 
       it('with average aggregation', async () => {
         const data = await renderTableForAggregation('Average');
-        expect(data).to.eql([['2.8510720308359434']]);
+        expect(data).to.eql([['2.8653795982259327']]);
       });
 
       it('with median aggregation', async () => {
@@ -79,7 +79,7 @@ export default function ({ getService, getPageObjects }: FtrProviderContext) {
 
       it('with sum aggregation', async () => {
         const data = await renderTableForAggregation('Sum');
-        expect(data).to.eql([['11834.800000000001']]);
+        expect(data).to.eql([['10983']]);
       });
     });
   });
diff --git a/x-pack/test/functional/es_archives/pre_calculated_histogram/data.json b/x-pack/test/functional/es_archives/pre_calculated_histogram/data.json
index 9efbf02681eda8..121a4036aaacdd 100644
--- a/x-pack/test/functional/es_archives/pre_calculated_histogram/data.json
+++ b/x-pack/test/functional/es_archives/pre_calculated_histogram/data.json
@@ -193,4 +193,23 @@
       }
     }
   }
-}
\ No newline at end of file
+}
+
+{
+  "type": "doc",
+  "value": {
+    "id": "5e694159d909d9d99b5e12d1",
+    "index": "histogram-test",
+    "source": {
+      "histogram-title": "single value",
+      "histogram-content": {
+        "values": [
+          1
+        ],
+        "counts": [
+          1
+        ]
+      }
+    }
+  }
+}