test for Decimal aggregateFunction normalization ClickHouse#39420

tests/queries/0_stateless/02366_decimal_agg_state_conversion.reference

@@ -0,0 +1,3 @@
+1.100001
+0.000001
+19	0.1

tests/queries/0_stateless/02366_decimal_agg_state_conversion.sql

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+select sumMerge(y) from 
+(
+  select cast(x, 'AggregateFunction(sum, Decimal(50, 10))') y from 
+   (
+     select arrayReduce('sumState', [toDecimal256('0.000001', 10), toDecimal256('1.1', 10)]) x
+   )
+);
+
+select minMerge(y) from 
+(
+  select cast(x, 'AggregateFunction(min, Decimal(18, 10))') y from 
+   (
+     select arrayReduce('minState', [toDecimal64('0.000001', 10), toDecimal64('1.1', 10)]) x
+   )
+);
+
+
+drop table if exists consumer_02366;
+drop table if exists producer_02366;
+drop table if exists mv_02366;
+
+CREATE TABLE consumer_02366
+(
+    `id` UInt16,
+    `dec` AggregateFunction(argMin, Decimal(24, 10), UInt16)
+)
+ENGINE = AggregatingMergeTree
+PRIMARY KEY id
+ORDER BY id;
+
+CREATE TABLE producer_02366
+(
+    `id` UInt16,
+    `dec` String
+)
+ENGINE = MergeTree
+PRIMARY KEY id
+ORDER BY id;
+
+CREATE MATERIALIZED VIEW mv_02366 TO consumer_02366 AS
+SELECT
+    id,
+    argMinState(dec, id) AS dec
+FROM
+(
+    SELECT
+        id,
+        toDecimal128(dec, 10) AS dec
+    FROM producer_02366
+)
+GROUP BY id;
+
+INSERT INTO producer_02366 (*) VALUES (19, '.1');
+
+SELECT
+    id,
+    finalizeAggregation(dec)
+FROM consumer_02366;
+
+drop table consumer_02366;
+drop table producer_02366;
+drop table mv_02366;