From 188c1c1dca68b7b855d2a7e5079b47928f2c4a18 Mon Sep 17 00:00:00 2001
From: Greg MacWilliam <greg.macwilliam@shopify.com>
Date: Tue, 9 Nov 2021 09:13:47 -0500
Subject: [PATCH] add tests.

---
 execution_test.go  | 49 ++++++++++++++++++++++++++++++++++++++++++++++
 query_execution.go |  2 +-
 2 files changed, 50 insertions(+), 1 deletion(-)

diff --git a/execution_test.go b/execution_test.go
index 938ec9e2..4328b159 100644
--- a/execution_test.go
+++ b/execution_test.go
@@ -2233,6 +2233,55 @@ func TestUnionAndTrimSelectionSet(t *testing.T) {
 		require.Equal(t, selectionSet, filtered)
 	})
 
+	t.Run("removes duplicate leaf values and merges composite scopes", func(t *testing.T) {
+		selectionSet := ast.SelectionSet{
+			&ast.Field{
+				Alias:            "name",
+				Name:             "name",
+				Definition:       schema.Types["Agent"].Fields.ForName("name"),
+				ObjectDefinition: schema.Types["Agent"],
+			},
+			&ast.Field{
+				Alias:            "name",
+				Name:             "name",
+				Definition:       schema.Types["Agent"].Fields.ForName("name"),
+				ObjectDefinition: schema.Types["Agent"],
+			},
+			&ast.Field{
+				Alias:            "country",
+				Name:             "country",
+				Definition:       schema.Types["Agent"].Fields.ForName("country"),
+				ObjectDefinition: schema.Types["Agent"],
+				SelectionSet: []ast.Selection{
+					&ast.Field{
+						Alias:            "id",
+						Name:             "id",
+						Definition:       schema.Types["Country"].Fields.ForName("id"),
+						ObjectDefinition: schema.Types["Country"],
+					},
+				},
+			},
+			&ast.Field{
+				Alias:            "country",
+				Name:             "country",
+				Definition:       schema.Types["Agent"].Fields.ForName("country"),
+				ObjectDefinition: schema.Types["Agent"],
+				SelectionSet: []ast.Selection{
+					&ast.Field{
+						Alias:            "name",
+						Name:             "name",
+						Definition:       schema.Types["Country"].Fields.ForName("name"),
+						ObjectDefinition: schema.Types["Country"],
+					},
+				},
+			},
+		}
+
+		filtered, err := unionAndTrimSelectionSet("", schema, selectionSet)
+		require.NoError(t, err)
+		require.Equal(t, formatSelectionSetSingleLine(ctx, schema, filtered), "{ name country { id name } }")
+	})
+
 	t.Run("removes field duplicates from inline fragment", func(t *testing.T) {
 		initialSelectionSet := ast.SelectionSet{
 			&ast.Field{
diff --git a/query_execution.go b/query_execution.go
index d71bb52b..0f15f50c 100644
--- a/query_execution.go
+++ b/query_execution.go
@@ -834,7 +834,7 @@ func unionAndTrimSelectionSetRec(objectTypename string, schema *ast.Schema, sele
 		switch selection := selection.(type) {
 		case *ast.Field:
 			if seenField, ok := seenFields[selection.Alias]; ok {
-				if seenField.SelectionSet != nil && selection.SelectionSet != nil {
+				if seenField.Name == selection.Name && seenField.SelectionSet != nil && selection.SelectionSet != nil {
 					seenField.SelectionSet = append(seenField.SelectionSet, selection.SelectionSet...)
 				}
 			} else {