Fix crash in codegen when only selection is __typename

apollographql · Jul 1, 2022 · 85e7015 · 85e7015
1 parent dd87224
commit 85e7015
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Showing 2 changed files with 36 additions and 1 deletion.
diff --git a/Sources/ApolloCodegenLib/IR/IR+EntitySelectionTree.swift b/Sources/ApolloCodegenLib/IR/IR+EntitySelectionTree.swift
@@ -149,7 +149,7 @@ extension IR {
         into selections: IR.MergedSelections
       ) {
         guard let nextTypePathNode = typePath.next else {
-          guard case let .fieldScope(node) = child else { fatalError() }
+          guard case let .fieldScope(node) = child else { return }
           node.mergeSelections(matchingScopePath: typePath, into: selections)
           return
         }

diff --git a/Tests/ApolloCodegenTests/CodeGeneration/Templates/FragmentTemplateTests.swift b/Tests/ApolloCodegenTests/CodeGeneration/Templates/FragmentTemplateTests.swift
@@ -288,6 +288,41 @@ class FragmentTemplateTests: XCTestCase {
     expect(actual).to(equalLineByLine(expected, atLine: 14, ignoringExtraLines: true))
   }
 
+  func test__render__givenFragmentWithOnlyTypenameField_generatesFragmentDefinition_withNoSelections() throws {
+    // given
+    document = """
+    fragment TestFragment on Animal {
+      __typename
+    }
+    """
+
+    try buildSubjectAndFragment()
+
+    let expected = """
+    struct TestFragment: TestSchema.SelectionSet, Fragment {
+      public static var fragmentDefinition: StaticString { ""\"
+        fragment TestFragment on Animal {
+          __typename
+        }
+        ""\" }
+
+      public let __data: DataDict
+      public init(data: DataDict) { __data = data }
+
+      public static var __parentType: ParentType { .Object(TestSchema.Animal.self) }
+      public static var selections: [Selection] { [
+      ] }
+    }
+
+    """
+
+    // when
+    let actual = renderSubject()
+
+    // then
+    expect(actual).to(equalLineByLine(expected))
+  }
+
   /// MARK: - Local Cache Mutation Tests
   func test__render__givenFragment__asLocalCacheMutation_generatesFragmentDeclarationDefinitionAsMutableSelectionSetAndBoilerplate() throws {
     // given