From 10f226c4c2e4da25a96c885a1dc936d60fe0ef19 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Torkel=20=C3=96degaard?= <torkel@grafana.org>
Date: Wed, 11 Nov 2020 07:43:56 +0100
Subject: [PATCH] StatPanels: Fixes auto min max when latest value is zero
 (#28982)

---
 .../src/field/fieldOverrides.test.ts          | 26 +++++++++++++++++--
 .../grafana-data/src/field/fieldOverrides.ts  | 20 +++++++-------
 2 files changed, 34 insertions(+), 12 deletions(-)

diff --git a/packages/grafana-data/src/field/fieldOverrides.test.ts b/packages/grafana-data/src/field/fieldOverrides.test.ts
index 44084927f6f..2cafeda0692 100644
--- a/packages/grafana-data/src/field/fieldOverrides.test.ts
+++ b/packages/grafana-data/src/field/fieldOverrides.test.ts
@@ -98,8 +98,30 @@ describe('Global MinMax', () => {
       });
       const { min, max } = findNumericFieldMinMax([frame]);
 
-      expect(min).toBeNull();
-      expect(max).toBeNull();
+      expect(min).toBe(Number.MIN_VALUE);
+      expect(max).toBe(Number.MAX_VALUE);
+    });
+  });
+
+  describe('when value values are zeo', () => {
+    it('then global min max should be correct', () => {
+      const frame = toDataFrame({
+        fields: [
+          { name: 'Time', type: FieldType.time, values: [1, 2] },
+          { name: 'Value', type: FieldType.number, values: [1, 2] },
+        ],
+      });
+      const frame2 = toDataFrame({
+        fields: [
+          { name: 'Time', type: FieldType.time, values: [1, 2] },
+          { name: 'Value', type: FieldType.number, values: [0, 0] },
+        ],
+      });
+
+      const { min, max } = findNumericFieldMinMax([frame, frame2]);
+
+      expect(min).toBe(0);
+      expect(max).toBe(2);
     });
   });
 });
diff --git a/packages/grafana-data/src/field/fieldOverrides.ts b/packages/grafana-data/src/field/fieldOverrides.ts
index fba14e335b2..dd00c243e43 100644
--- a/packages/grafana-data/src/field/fieldOverrides.ts
+++ b/packages/grafana-data/src/field/fieldOverrides.ts
@@ -58,25 +58,25 @@ export function findNumericFieldMinMax(data: DataFrame[]): GlobalMinMax {
         const statsMin = stats[ReducerID.min];
         const statsMax = stats[ReducerID.max];
 
-        if (!statsMin) {
+        if (statsMin !== undefined && statsMin !== null && statsMin < min) {
           min = statsMin;
         }
 
-        if (!statsMax) {
-          max = statsMax;
-        }
-
-        if (statsMin && statsMin < min) {
-          min = statsMin;
-        }
-
-        if (statsMax && statsMax > max) {
+        if (statsMax !== undefined && statsMax !== null && statsMax > max) {
           max = statsMax;
         }
       }
     }
   }
 
+  if (min === Number.MAX_VALUE) {
+    min = Number.MIN_VALUE;
+  }
+
+  if (max === Number.MIN_VALUE) {
+    max = Number.MAX_VALUE;
+  }
+
   return { min, max };
 }