test(strawberry-shake): regression guard for inheritance codegen (#5593)

src/StrawberryShake/CodeGeneration/test/CodeGeneration.CSharp.Tests/InheritanceGeneratorTests.cs

@@ -0,0 +1,96 @@
+using static StrawberryShake.CodeGeneration.CSharp.GeneratorTestHelper;
+
+namespace StrawberryShake.CodeGeneration.CSharp;
+
+// Regression guard for ChilliCream/graphql-platform#5593, where two object types
+// sharing a common interface base (Exercise and Survey both implementing Activity)
+// caused the generator to emit a duplicate base class. The scenario generates
+// correctly on the current type-system pipeline; these tests lock that in.
+public class InheritanceGeneratorTests
+{
+    private const string EntityInterfaceSchema =
+        @"type Query {
+                activities: [Activity!]!
+                activitiesPaged: ActivitiesPagedConnection
+            }
+
+            interface Activity {
+                id: Uuid!
+                activityType: String!
+                description: String
+                name: String!
+            }
+
+            type Exercise implements Activity {
+                id: Uuid!
+                activityType: String!
+                category: ExerciseCategory!
+                description: String
+                name: String!
+            }
+
+            type Survey implements Activity {
+                id: Uuid!
+                activityType: String!
+                description: String
+                name: String!
+            }
+
+            type ActivitiesPagedConnection {
+                nodes: [Activity!]
+                totalCount: Int!
+            }
+
+            enum ExerciseCategory {
+                NONE
+                CATEGORY1
+                CATEGORY2
+            }
+
+            scalar Uuid";
+
+    [Fact]
+    public void Interface_Entity_With_Two_Implementations_InlineFragments()
+    {
+        AssertResult(
+            @"query GetActivities {
+                    activities {
+                        id
+                        activityType
+                        name
+                        ... on Exercise {
+                            category
+                        }
+                        ... on Survey {
+                            description
+                        }
+                    }
+                }",
+            EntityInterfaceSchema,
+            "extend schema @key(fields: \"id\")");
+    }
+
+    [Fact]
+    public void Interface_Entity_Connection_With_Two_Implementations()
+    {
+        AssertResult(
+            @"query GetActivitiesPaged {
+                    activitiesPaged {
+                        nodes {
+                            id
+                            activityType
+                            name
+                            ... on Exercise {
+                                category
+                            }
+                            ... on Survey {
+                                description
+                            }
+                        }
+                        totalCount
+                    }
+                }",
+            EntityInterfaceSchema,
+            "extend schema @key(fields: \"id\")");
+    }
+}