Transpile tests to kotlin and add nullable annotations in graqhql response exception

Author: jvh-aws

aws-api/src/main/java/com/amplifyframework/api/aws/GraphQLResponseException.java

@@ -105,6 +105,7 @@ public static final class GraphQLError {
          * Gets the error type (AWS AppSync extension).
          * @return The error type, or null if not present
          */
+        @Nullable
         public String getErrorType() {
             return errorType;
         }
@@ -113,6 +114,7 @@ public String getErrorType() {
          * Gets the error message.
          * @return The error message, or null if not present
          */
+        @Nullable
         public String getMessage() {
             return message;
         }
@@ -121,6 +123,7 @@ public String getMessage() {
          * Gets the error code.
          * @return The error code, or null if not present
          */
+        @Nullable
         public Integer getErrorCode() {
             return errorCode;
         }

aws-api/src/test/java/com/amplifyframework/api/aws/AppSyncErrorPropagationTest.java

@@ -0,0 +1,151 @@
+/*
+ * Copyright 2026 Amazon.com, Inc. or its affiliates. All Rights Reserved.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License").
+ * You may not use this file except in compliance with the License.
+ * A copy of the License is located at
+ *
+ *  http://aws.amazon.com/apache2.0
+ *
+ * or in the "license" file accompanying this file. This file is distributed
+ * on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either
+ * express or implied. See the License for the specific language governing
+ * permissions and limitations under the License.
+ */
+
+package com.amplifyframework.api.aws
+
+import androidx.test.core.app.ApplicationProvider
+import com.amplifyframework.AmplifyException
+import com.amplifyframework.api.ApiException
+import com.amplifyframework.api.graphql.model.ModelQuery
+import com.amplifyframework.testutils.Await
+import io.kotest.matchers.nulls.shouldNotBeNull
+import io.kotest.matchers.shouldBe
+import io.kotest.matchers.types.shouldBeInstanceOf
+import okhttp3.HttpUrl
+import okhttp3.mockwebserver.MockResponse
+import okhttp3.mockwebserver.MockWebServer
+import org.json.JSONException
+import org.json.JSONObject
+import org.junit.After
+import org.junit.Before
+import org.junit.Test
+import org.junit.runner.RunWith
+import org.robolectric.RobolectricTestRunner
+import java.io.IOException
+
+/**
+ * Integration tests for error cause propagation in GraphQL operations.
+ * Tests that exception causes are properly preserved when API calls fail.
+ */
+@RunWith(RobolectricTestRunner::class)
+class AppSyncErrorPropagationTest {
+    private lateinit var webServer: MockWebServer
+    private lateinit var baseUrl: HttpUrl
+    private lateinit var plugin: AWSApiPlugin
+
+    /**
+     * Sets up the test with a mock web server.
+     * @throws IOException On failure to start web server
+     * @throws JSONException On failure to arrange configuration JSON
+     * @throws AmplifyException On failure to configure plugin
+     */
+    @Before
+    @Throws(AmplifyException::class, IOException::class, JSONException::class)
+    fun setup() {
+        webServer = MockWebServer()
+        webServer.start(8080)
+        baseUrl = webServer.url("/")
+
+        val configuration = JSONObject()
+            .put("graphQlApi", JSONObject()
+                .put("endpointType", "GraphQL")
+                .put("endpoint", baseUrl.toUrl())
+                .put("region", "us-east-1")
+                .put("authorizationType", "API_KEY")
+                .put("apiKey", "FAKE-API-KEY"))
+
+        plugin = AWSApiPlugin.builder().build()
+        plugin.configure(configuration, ApplicationProvider.getApplicationContext())
+    }
+
+    /**
+     * Stop the [MockWebServer] that was started in [setup].
+     * @throws IOException On failure to shutdown the MockWebServer
+     */
+    @After
+    @Throws(IOException::class)
+    fun cleanup() {
+        webServer.shutdown()
+    }
+
+    /**
+     * Tests that query 401 errors preserve the GraphQL error response as the cause.
+     * The cause should be a GraphQLResponseException containing the error details.
+     */
+    @Test
+    fun queryUnauthorizedErrorPreservesCause() {
+        // Arrange - mock a 401 response with GraphQL error payload
+        val errorResponse = """
+            {
+              "errors": [{
+                "errorType": "UnauthorizedException",
+                "message": "You are not authorized to make this call."
+              }]
+            }
+        """.trimIndent()
+        
+        webServer.enqueue(MockResponse()
+            .setResponseCode(401)
+            .setBody(errorResponse))
+
+        // Act - execute query and capture error
+        val error = Await.error { onResult, onError ->
+            plugin.query(ModelQuery.list(Todo::class.java), onResult, onError)
+        }
+
+        // Assert - verify error has proper cause chain
+        error.shouldNotBeNull()
+        error.shouldBeInstanceOf<ApiException.NonRetryableException>()
+        
+        val cause = error.cause
+        cause.shouldNotBeNull()
+        cause.shouldBeInstanceOf<GraphQLResponseException>()
+
+        cause.errors.size.shouldBe(1)
+        
+        val firstError = cause.errors[0]
+        firstError.errorType.shouldBe("UnauthorizedException")
+        firstError.message.shouldBe("You are not authorized to make this call.")
+    }
+
+    /**
+     * Tests that query errors with invalid JSON fall back to IOException with JSONException cause.
+     */
+    @Test
+    fun queryInvalidJsonPreservesJsonException() {
+        // Arrange - mock a 400 response with invalid JSON
+        val invalidJson = "not valid json at all"
+        
+        webServer.enqueue(MockResponse()
+            .setResponseCode(400)
+            .setBody(invalidJson))
+
+        // Act
+        val error = Await.error { onResult, onError ->
+            plugin.query(ModelQuery.list(Todo::class.java), onResult, onError)
+        }
+
+        // Assert
+        error.shouldNotBeNull()
+        val cause = error.cause
+        cause.shouldNotBeNull()
+        cause.shouldBeInstanceOf<IOException>()
+        
+        // The IOException should have a JSONException as its cause
+        val jsonCause = cause.cause
+        jsonCause.shouldNotBeNull()
+        jsonCause.shouldBeInstanceOf<JSONException>()
+    }
+}