Fix searchMsearchRequest to use Min(size, maxResults) as actual pageSize

See spring-projects#3089

Author: hy2850

src/main/java/org/springframework/data/elasticsearch/client/elc/RequestConverter.java

@@ -1310,9 +1310,11 @@ public MsearchRequest searchMsearchRequest(
 								bb.storedFields(query.getStoredFields());
 							}
 
-							if (query.isLimiting()) {
-								bb.size(query.getMaxResults());
-							}
+                            var maxResults = query.getMaxResults();
+                            if (query.isLimiting() && maxResults != null) {
+                                var pageSize = Math.min(maxResults, query.getPageable().getPageSize());
+                                bb.size(pageSize);
+                            }
 
 							if (query.getMinScore() > 0) {
 								bb.minScore((double) query.getMinScore());

src/test/java/org/springframework/data/elasticsearch/client/elc/RequestConverterTest.java

@@ -91,7 +91,7 @@ void refreshSetByDeleteRequest() {
 	}
 
     @Test
-    @DisplayName("When maxResults is set (size < maxResults), pageSize should be the minimum of maxResults and pageable size")
+    @DisplayName("searchRequest() - When maxResults is set (size < maxResults), pageSize should be the minimum of maxResults and pageable size")
     void searchRequestPageSizeSmallerThanMaxResults() {
         var size = 123;
         var maxResults = size * 12;
@@ -113,7 +113,7 @@ void searchRequestPageSizeSmallerThanMaxResults() {
     }
 
     @Test
-    @DisplayName("When maxResults is set (size == maxResults), pageSize should be equal to maxResults and pageable size")
+    @DisplayName("searchRequest() - When maxResults is set (size == maxResults), pageSize should be equal to maxResults and pageable size")
     void searchRequestPageSizeEqualToMaxResults() {
         var pageSize = 123;
         var maxResults = pageSize;
@@ -135,7 +135,7 @@ void searchRequestPageSizeEqualToMaxResults() {
     }
 
     @Test
-    @DisplayName("When maxResults is set (size > maxResults), pageSize should be the minimum of maxResults and pageable size")
+    @DisplayName("searchRequest() - When maxResults is set (size > maxResults), pageSize should be the minimum of maxResults and pageable size")
     void searchRequestPageSizeLargerThanMaxResults() {
         var pageSize = 123;
         var maxResults = 99;
@@ -156,6 +156,87 @@ void searchRequestPageSizeLargerThanMaxResults() {
         assertThat(actualPageSize).isEqualTo(maxResults);
     }
 
+    @Test
+    @DisplayName("searchMsearchRequest() - When maxResults is set (size < maxResults), pageSize should be the minimum of maxResults and pageable size")
+    void msearchRequestPageSizeSmallerThanMaxResults() {
+        var size = 100;
+        var maxResults = 150;
+
+        var query = StringQuery.builder("""
+                        {
+                            "match_all":{}
+                        }
+                        """)
+                .withPageable(Pageable.ofSize(size))
+                .withMaxResults(maxResults)
+                .build();
+
+        var multiSearchQueryParameter = new ElasticsearchTemplate.MultiSearchQueryParameter(query, SampleEntity.class, IndexCoordinates.of("foo"));
+        var multiSearchQueryParameters = List.of(multiSearchQueryParameter);
+
+        var msearchRequest = requestConverter.searchMsearchRequest(multiSearchQueryParameters, null);
+
+        var searchBody = msearchRequest.searches().get(0).body();
+        var actualPageSize = searchBody.size();
+
+        assertThat(actualPageSize).isEqualTo(size);
+        assertThat(actualPageSize).isNotEqualTo(maxResults);
+    }
+
+    @Test
+    @DisplayName("searchMsearchRequest() - When maxResults is set (size == maxResults), pageSize should be equal to maxResults and pageable size")
+    void msearchRequestPageSizeEqualToMaxResults() {
+        var size = 150;
+        var maxResults = size;
+
+        var query = StringQuery.builder("""
+                        {
+                            "match_all":{}
+                        }
+                        """)
+                .withPageable(Pageable.ofSize(size))
+                .withMaxResults(maxResults)
+                .build();
+
+        var multiSearchQueryParameter = new ElasticsearchTemplate.MultiSearchQueryParameter(query, SampleEntity.class, IndexCoordinates.of("foo"));
+        var multiSearchQueryParameters = List.of(multiSearchQueryParameter);
+
+        var msearchRequest = requestConverter.searchMsearchRequest(multiSearchQueryParameters, null);
+
+        var searchBody = msearchRequest.searches().get(0).body();
+        var actualPageSize = searchBody.size();
+
+        assertThat(actualPageSize).isEqualTo(size);
+        assertThat(actualPageSize).isEqualTo(maxResults);
+    }
+
+    @Test
+    @DisplayName("searchMsearchRequest() - When maxResults is set (size > maxResults), pageSize should be the minimum of maxResults and pageable size")
+    void msearchRequestPageSizeLargerThanMaxResults() {
+        var size = 200;
+        var maxResults = 150;
+
+        var query = StringQuery.builder("""
+                        {
+                            "match_all":{}
+                        }
+                        """)
+                .withPageable(Pageable.ofSize(size))
+                .withMaxResults(maxResults)
+                .build();
+
+        var multiSearchQueryParameter = new ElasticsearchTemplate.MultiSearchQueryParameter(query, SampleEntity.class, IndexCoordinates.of("foo"));
+        var multiSearchQueryParameters = List.of(multiSearchQueryParameter);
+
+        var msearchRequest = requestConverter.searchMsearchRequest(multiSearchQueryParameters, null);
+
+        var searchBody = msearchRequest.searches().get(0).body();
+        var actualPageSize = searchBody.size();
+
+        assertThat(actualPageSize).isNotEqualTo(size);
+        assertThat(actualPageSize).isEqualTo(maxResults);
+    }
+
 	@Document(indexName = "does-not-matter")
 	static class SampleEntity {
 		@Nullable