From 77ce22e8d8ac4cbb37c19879659df729e67422b1 Mon Sep 17 00:00:00 2001
From: JessamineQ <jessamine.qu0@gmail.com>
Date: Mon, 22 Apr 2024 02:01:10 -0400
Subject: [PATCH] fix: for issue when there are multiple aggregates for same
 data field and aggregation operation

---
 src/compile/data/aggregate.ts |  3 ++-
 test/compile/compile.test.ts  | 19 +++++++++++++++++++
 2 files changed, 21 insertions(+), 1 deletion(-)

diff --git a/src/compile/data/aggregate.ts b/src/compile/data/aggregate.ts
index a8a9cefba1..87b73ecabd 100644
--- a/src/compile/data/aggregate.ts
+++ b/src/compile/data/aggregate.ts
@@ -164,7 +164,8 @@ export class AggregateNode extends DataFlowNode {
           meas['*']['count'] = new Set([as ? as : vgField(s, {forAs: true})]);
         } else {
           meas[field] ??= {};
-          meas[field][op] = new Set([as ? as : vgField(s, {forAs: true})]);
+          meas[field][op] ??= new Set();
+          meas[field][op].add(as ? as : vgField(s, {forAs: true}));
         }
       }
     }
diff --git a/test/compile/compile.test.ts b/test/compile/compile.test.ts
index e4667bdc07..3991e35bc9 100644
--- a/test/compile/compile.test.ts
+++ b/test/compile/compile.test.ts
@@ -1,3 +1,4 @@
+import {AggregateTransform} from 'vega';
 import {compile} from '../../src/compile/compile';
 import * as log from '../../src/log';
 
@@ -573,3 +574,21 @@ describe('compile/compile', () => {
     expect(spec.autosize['resize']).toBeTruthy();
   });
 });
+
+it('should generate right tooltip', () => {
+  const {spec} = compile({
+    data: {url: 'data/population.json'},
+    mark: 'errorband',
+    encoding: {
+      x: {field: 'age', type: 'ordinal'},
+      y: {field: 'people', type: 'quantitative'},
+      tooltip: {field: 'people', aggregate: 'mean'}
+    }
+  });
+
+  expect((spec.data[0].transform[0] as AggregateTransform).as as string[]).toEqual([
+    'mean_people',
+    'center_people',
+    'extent_people'
+  ]);
+});