fix NPE when response is null

build.gradle

@@ -5,7 +5,7 @@ plugins {
 
 allprojects {
     group = 'com.strategyobject.substrateclient'
-    version = '0.0.3-SNAPSHOT'
+    version = '0.0.4-SNAPSHOT'
 
     repositories {
         mavenLocal()

crypto/build.gradle

@@ -1,6 +1,6 @@
 dependencies {
     implementation 'com.github.multiformats:java-multibase:1.1.0'
-    implementation 'org.bouncycastle:bcprov-jdk15on:1.69'
+    implementation 'org.bouncycastle:bcprov-jdk15on:1.70'
     implementation project(":common")
     implementation project(":types")
 }

rpc/rpc-codegen/build.gradle

@@ -10,7 +10,7 @@ dependencies {
 
     implementation 'com.squareup:javapoet:1.13.0'
     testImplementation 'com.google.testing.compile:compile-testing:0.19'
-    testImplementation 'com.google.code.gson:gson:2.8.9'
+    testImplementation 'com.google.code.gson:gson:2.9.0'
 
     testCompileOnly project(':rpc:rpc-codegen')
     testAnnotationProcessor project(':rpc:rpc-codegen')

rpc/rpc-core/build.gradle

@@ -3,5 +3,5 @@ dependencies {
     implementation project(':scale')
     implementation project(':transport')
 
-    testImplementation 'com.google.code.gson:gson:2.8.9'
+    testImplementation 'com.google.code.gson:gson:2.9.0'
 }

rpc/rpc-sections/build.gradle

@@ -17,7 +17,7 @@ dependencies {
 
     testImplementation 'org.testcontainers:testcontainers:1.16.3'
     testImplementation 'org.testcontainers:junit-jupiter:1.16.3'
-    testImplementation 'ch.qos.logback:logback-classic:1.2.10'
-    testImplementation 'org.awaitility:awaitility:4.1.1'
-    testImplementation 'org.bouncycastle:bcprov-jdk15on:1.69'
+    testImplementation 'ch.qos.logback:logback-classic:1.2.11'
+    testImplementation 'org.awaitility:awaitility:4.2.0'
+    testImplementation 'org.bouncycastle:bcprov-jdk15on:1.70'
 }

rpc/rpc-sections/src/test/java/com/strategyobject/substrateclient/rpc/sections/StateTests.java

@@ -18,8 +18,7 @@
 import java.util.concurrent.TimeUnit;
 import java.util.concurrent.TimeoutException;
 
-import static org.junit.jupiter.api.Assertions.assertDoesNotThrow;
-import static org.junit.jupiter.api.Assertions.assertTrue;
+import static org.junit.jupiter.api.Assertions.*;
 
 @Testcontainers
 public class StateTests {
@@ -100,11 +99,29 @@ void getStorage() throws ExecutionException, InterruptedException, TimeoutExcept
             val key = "0xc2261276cc9d1f8598ea4b6a74b15c2f308ce9615de0775a82f8a94dc3d285a1"; // TODO implement and use `xxhash`
             val storageData = rpcSection.getStorage(StorageKey.valueOf(HexConverter.toBytes(key))).get(WAIT_TIMEOUT, TimeUnit.SECONDS);
 
-            assertTrue(storageData != null);
+            assertNotNull(storageData);
             assertTrue(storageData.getData().length > 0);
         }
     }
 
+    @Test
+    void getStorageHandlesNullResponse() throws ExecutionException, InterruptedException, TimeoutException, RpcInterfaceInitializationException {
+        try (WsProvider wsProvider = WsProvider.builder()
+                .setEndpoint(substrate.getWsAddress())
+                .disableAutoConnect()
+                .build()) {
+            wsProvider.connect().get(WAIT_TIMEOUT, TimeUnit.SECONDS);
+
+            val sectionFactory = new RpcGeneratedSectionFactory();
+            State rpcSection = sectionFactory.create(State.class, wsProvider);
+
+            val emptyKey = new byte[32];
+            val storageData = rpcSection.getStorage(StorageKey.valueOf(emptyKey)).get(WAIT_TIMEOUT, TimeUnit.SECONDS);
+
+            assertNull(storageData);
+        }
+    }
+
     @Test
     void getStorageAt() throws ExecutionException, InterruptedException, TimeoutException, RpcInterfaceInitializationException {
         try (WsProvider wsProvider = WsProvider.builder()
@@ -123,7 +140,7 @@ void getStorageAt() throws ExecutionException, InterruptedException, TimeoutExce
 
             assertTrue(changes.size() > 0);
             assertTrue(changes.get(0).getChanges().size() > 0);
-            assertTrue(changes.get(0).getChanges().get(0).getValue0().getData() != null);
+            assertNotNull(changes.get(0).getChanges().get(0).getValue0().getData());
             assertTrue(changes.get(0).getChanges().get(0).getValue0().getData().length > 0);
         }
     }

transport/build.gradle

@@ -2,12 +2,12 @@ dependencies {
     implementation project(':common')
 
     implementation 'org.java-websocket:Java-WebSocket:1.5.2'
-    implementation 'com.google.code.gson:gson:2.8.9'
+    implementation 'com.google.code.gson:gson:2.9.0'
 
     testImplementation project(':tests')
-    testImplementation 'ch.qos.logback:logback-classic:1.2.10'
+    testImplementation 'ch.qos.logback:logback-classic:1.2.11'
     testImplementation 'org.testcontainers:testcontainers:1.16.3'
     testImplementation 'org.testcontainers:junit-jupiter:1.16.3'
     testImplementation "org.testcontainers:toxiproxy:1.16.3"
-    testImplementation 'org.awaitility:awaitility:4.1.1'
+    testImplementation 'org.awaitility:awaitility:4.2.0'
 }

transport/src/main/java/com/strategyobject/substrateclient/transport/coder/RpcCoder.java

@@ -9,7 +9,7 @@
 
 public class RpcCoder {
     private static final Gson GSON = new GsonBuilder()
-            .registerTypeAdapter(RpcObject.class, new RpcObjectDeserializer())
+            .registerTypeAdapter(RpcObject.class, new RpcObjectTypeAdapter())
             .create();
 
     private final AtomicInteger id = new AtomicInteger(0);

transport/src/main/java/com/strategyobject/substrateclient/transport/coder/RpcObjectTypeAdapter.java

@@ -0,0 +1,51 @@
+package com.strategyobject.substrateclient.transport.coder;
+
+import com.google.gson.TypeAdapter;
+import com.google.gson.stream.JsonReader;
+import com.google.gson.stream.JsonWriter;
+import com.strategyobject.substrateclient.transport.*;
+import lombok.val;
+
+import java.io.IOException;
+import java.util.ArrayList;
+import java.util.HashMap;
+
+public class RpcObjectTypeAdapter extends TypeAdapter<RpcObject> {
+    @Override
+    public void write(JsonWriter out, RpcObject value) throws IOException {
+        throw new UnsupportedOperationException();
+    }
+
+    @Override
+    public RpcObject read(JsonReader in) throws IOException {
+        switch (in.peek()) {
+            case NULL:
+                in.nextNull();
+                return new RpcNull();
+            case BOOLEAN:
+                return new RpcBoolean(in.nextBoolean());
+            case NUMBER:
+                return new RpcNumber(in.nextDouble());
+            case STRING:
+                return new RpcString(in.nextString());
+            case BEGIN_ARRAY:
+                in.beginArray();
+                val list = new ArrayList<RpcObject>();
+                while (in.hasNext()) {
+                    list.add(this.read(in));
+                }
+
+                in.endArray();
+                return new RpcList(list);
+            default:
+                in.beginObject();
+                val map = new HashMap<String, RpcObject>();
+                while (in.hasNext()) {
+                    map.put(in.nextName(), this.read(in));
+                }
+
+                in.endObject();
+                return new RpcMap(map);
+        }
+    }
+}

transport/src/test/java/com/strategyobject/substrateclient/transport/coder/RpcCoderTest.java

@@ -12,6 +12,24 @@
 
 class RpcCoderTest {
 
+    @Test
+    void decodeNullResult() {
+        val json = "{\n" +
+                "    \"result\": null,\n" +
+                "    \"id\": 0,\n" +
+                "    \"jsonrpc\": \"3.0\"\n" +
+                "}";
+        val actual = RpcCoder.decodeJson(json);
+
+        val expected = new JsonRpcResponse();
+        expected.jsonrpc = "3.0";
+        expected.id = 0;
+        expected.result = RpcObject.ofNull();
+        assertThat(actual)
+                .usingRecursiveComparison()
+                .isEqualTo(expected);
+    }
+
     @Test
     void decodeJson() {
         val json = "{\n" +