fix: Cache write interceptor should gracefully handle missing cache records

Tests/ApolloTests/RequestChainTests.swift

@@ -295,6 +295,56 @@
     }
   }
 
+  func test__error__givenGraphqlError_withoutData_shouldReturnError() {
+    // given
+    let client = MockURLSessionClient(
+      response: .mock(
+        url: TestURL.mockServer.url,
+        statusCode: 200,
+        httpVersion: nil,
+        headerFields: nil
+      ),
+      data: """
+      {
+        "errors": [{
+          "message": "Bad request, could not start execution!"
+        }]
+      }
+      """.data(using: .utf8)
+    )
+
+    let interceptorProvider = DefaultInterceptorProvider(client: client, store: ApolloStore())
+    let interceptors = interceptorProvider.interceptors(for: MockQuery.mock())
+    let requestChain = InterceptorRequestChain(interceptors: interceptors)
+
+    let expectation = expectation(description: "Response received")
+
+    let request = JSONRequest(
+      operation: MockQuery<Hero>(),
+      graphQLEndpoint: TestURL.mockServer.url,
+      clientName: "test-client",
+      clientVersion: "test-client-version"
+    )
+
+    // when + then
+    requestChain.kickoff(request: request) { result in
+      defer {
+        expectation.fulfill()
+      }
+
+      switch (result) {
+      case let .success(data):
+        XCTAssertEqual(data.errors, [
+          GraphQLError("Bad request, could not start execution!")
+        ])
+      case let .failure(error):
+        XCTFail("Unexpected failure result - \(error)")
+      }
+    }
+
+    wait(for: [expectation], timeout: 1)
+  }
+
   // MARK: Multipart request tests
 
   struct RequestTrapInterceptor: ApolloInterceptor {
@@ -882,7 +932,7 @@
     throw XCTSkip("Flaky test skipped in PR #386- must be refactored or fixed in a separate PR.")
 
     // given
     let store = ApolloStore(cache: InMemoryNormalizedCache(records: [
       "QUERY_ROOT": [
         "__typename": "Hero",
         "name": "R2-D2"

apollo-ios/Sources/Apollo/CacheWriteInterceptor.swift

@@ -7,17 +7,12 @@ import ApolloAPI
 public struct CacheWriteInterceptor: ApolloInterceptor {
 
   public enum CacheWriteError: Error, LocalizedError {
-    @available(*, deprecated, message: "Will be removed in a future version.")
     case noResponseToParse
 
-    case missingCacheRecords
-
     public var errorDescription: String? {
       switch self {
       case .noResponseToParse:
         return "The Cache Write Interceptor was called before a response was received to be parsed. Double-check the order of your interceptors."
-      case .missingCacheRecords:
-        return "The Cache Write Interceptor cannot find any cache records. Double-check the order of your interceptors."
       }
     }
   }
@@ -37,7 +32,11 @@ public struct CacheWriteInterceptor: ApolloInterceptor {
     request: HTTPRequest<Operation>,
     response: HTTPResponse<Operation>?,
     completion: @escaping (Result<GraphQLResult<Operation.Data>, any Error>) -> Void) {
-
+
+    guard !chain.isCancelled else {
+      return
+    }
+
     guard request.cachePolicy != .fetchIgnoringCacheCompletely else {
       // If we're ignoring the cache completely, we're not writing to it.
       chain.proceedAsync(
@@ -49,25 +48,20 @@ public struct CacheWriteInterceptor: ApolloInterceptor {
       return
     }
 
-    guard
-      let createdResponse = response,
-      let cacheRecords = createdResponse.cacheRecords
-    else {
+    guard let createdResponse = response else {
       chain.handleErrorAsync(
-        CacheWriteError.missingCacheRecords,
+        CacheWriteError.noResponseToParse,
         request: request,
         response: response,
         completion: completion
       )
       return
     }
 
-    guard !chain.isCancelled else {
-      return
+    if let cacheRecords = createdResponse.cacheRecords {
+      self.store.publish(records: cacheRecords, identifier: request.contextIdentifier)
     }
 
-    self.store.publish(records: cacheRecords, identifier: request.contextIdentifier)
-
     chain.proceedAsync(
       request: request,
       response: createdResponse,