Get rid of jackson (mostly)

Reviewed By: astreet

Differential Revision: D3041362

fb-gh-sync-id: a7027a08a63730b98dc766b86921820fa3624953
shipit-source-id: a7027a08a63730b98dc766b86921820fa3624953

ReactAndroid/src/main/java/com/facebook/react/bridge/BaseJavaModule.java

@@ -9,8 +9,6 @@
 
 package com.facebook.react.bridge;
 
-import com.fasterxml.jackson.core.JsonGenerator;
-
 import com.facebook.infer.annotation.Assertions;
 import com.facebook.systrace.Systrace;
 
@@ -325,20 +323,18 @@ public abstract class BaseJavaModule implements NativeModule {
   }
 
   @Override
-  public final void writeConstantsField(JsonGenerator jg, String fieldName) throws IOException {
+  public final void writeConstantsField(JsonWriter writer, String fieldName) throws IOException {
     Map<String, Object> constants = getConstants();
     if (constants == null || constants.isEmpty()) {
       return;
     }
 
-    jg.writeObjectFieldStart(fieldName);
+    writer.name(fieldName).beginObject();
     for (Map.Entry<String, Object> constant : constants.entrySet()) {
-      JsonGeneratorHelper.writeObjectField(
+      writer.name(constant.getKey());
-        jg,
+      JsonWriterHelper.value(writer, constant.getValue());
-        constant.getKey(),
-        constant.getValue());
     }
-    jg.writeEndObject();
+    writer.endObject();
   }
 
   @Override

ReactAndroid/src/main/java/com/facebook/react/bridge/CatalystInstanceImpl.java

@@ -31,9 +31,6 @@ import com.facebook.react.common.futures.SimpleSettableFuture;
 import com.facebook.systrace.Systrace;
 import com.facebook.systrace.TraceListener;
 
-import com.fasterxml.jackson.core.JsonFactory;
-import com.fasterxml.jackson.core.JsonGenerator;
-
 /**
  * This provides an implementation of the public CatalystInstance instance.  It is public because
  * it is built by ReactInstanceManager which is in a different package.
@@ -358,21 +355,24 @@ public class CatalystInstanceImpl implements CatalystInstance {
   private String buildModulesConfigJSONProperty(
       NativeModuleRegistry nativeModuleRegistry,
       JavaScriptModulesConfig jsModulesConfig) {
-    JsonFactory jsonFactory = new JsonFactory();
+    StringWriter stringWriter = new StringWriter();
-    StringWriter writer = new StringWriter();
+    JsonWriter writer = new JsonWriter(stringWriter);
     try {
-      JsonGenerator jg = jsonFactory.createGenerator(writer);
+      writer.beginObject();
-      jg.writeStartObject();
+      writer.name("remoteModuleConfig");
-      jg.writeFieldName("remoteModuleConfig");
+      nativeModuleRegistry.writeModuleDescriptions(writer);
-      nativeModuleRegistry.writeModuleDescriptions(jg);
+      writer.name("localModulesConfig");
-      jg.writeFieldName("localModulesConfig");
+      jsModulesConfig.writeModuleDescriptions(writer);
-      jsModulesConfig.writeModuleDescriptions(jg);
+      writer.endObject();
-      jg.writeEndObject();
+      return stringWriter.toString();
-      jg.close();
     } catch (IOException ioe) {
       throw new RuntimeException("Unable to serialize JavaScript module declaration", ioe);
+    } finally {
+      try {
+        writer.close();
+      } catch (IOException ignored) {
+      }
     }
-    return writer.getBuffer().toString();
   }
 
   private void incrementPendingJSCalls() {

ReactAndroid/src/main/java/com/facebook/react/bridge/JavaScriptModulesConfig.java

@@ -14,8 +14,6 @@ import java.lang.reflect.Method;
 import java.util.ArrayList;
 import java.util.List;
 
-import com.fasterxml.jackson.core.JsonGenerator;
-
 /**
  * Class stores configuration of javascript modules that can be used across the bridge
  */
@@ -31,29 +29,29 @@ public class JavaScriptModulesConfig {
     return mModules;
   }
 
-  public void writeModuleDescriptions(JsonGenerator jg) throws IOException {
+  public void writeModuleDescriptions(JsonWriter writer) throws IOException {
-    jg.writeStartObject();
+    writer.beginObject();
     for (JavaScriptModuleRegistration registration : mModules) {
-      jg.writeObjectFieldStart(registration.getName());
+      writer.name(registration.getName()).beginObject();
-      appendJSModuleToJSONObject(jg, registration);
+      appendJSModuleToJSONObject(writer, registration);
-      jg.writeEndObject();
+      writer.endObject();
     }
-    jg.writeEndObject();
+    writer.endObject();
   }
 
   private void appendJSModuleToJSONObject(
-      JsonGenerator jg,
+      JsonWriter writer,
       JavaScriptModuleRegistration registration) throws IOException {
-    jg.writeObjectField("moduleID", registration.getModuleId());
+    writer.name("moduleID").value(registration.getModuleId());
-    jg.writeObjectFieldStart("methods");
+    writer.name("methods").beginObject();
     for (Method method : registration.getMethods()) {
-      jg.writeObjectFieldStart(method.getName());
+      writer.name(method.getName()).beginObject();
-      jg.writeObjectField("methodID", registration.getMethodId(method));
+      writer.name("methodID").value(registration.getMethodId(method));
-      jg.writeEndObject();
+      writer.endObject();
     }
-    jg.writeEndObject();
+    writer.endObject();
     if (registration.getModuleInterface().isAnnotationPresent(SupportsWebWorkers.class)) {
-      jg.writeBooleanField("supportsWebWorkers", true);
+      writer.name("supportsWebWorkers").value(true);
     }
   }
 

ReactAndroid/src/main/java/com/facebook/react/bridge/JsonGeneratorHelper.java

@@ -1,54 +0,0 @@
-/**
- * Copyright (c) 2015-present, Facebook, Inc.
- * All rights reserved.
- *
- * This source code is licensed under the BSD-style license found in the
- * LICENSE file in the root directory of this source tree. An additional grant
- * of patent rights can be found in the PATENTS file in the same directory.
- */
-
-package com.facebook.react.bridge;
-
-import java.io.IOException;
-import java.util.List;
-import java.util.Map;
-import java.util.Set;
-
-import com.fasterxml.jackson.core.JsonGenerator;
-
-/**
- * Helper for generating JSON for lists and maps.
- */
-public class JsonGeneratorHelper {
-
-  /**
-   * Like {@link JsonGenerator#writeObjectField(String, Object)} but supports Maps and Lists.
-   */
-  public static void writeObjectField(JsonGenerator jg, String name, Object object)
-      throws IOException {
-    if (object instanceof Map) {
-      writeMap(jg, name, (Map) object);
-    } else if (object instanceof List) {
-      writeList(jg, name, (List) object);
-    } else {
-      jg.writeObjectField(name, object);
-    }
-  }
-
-  private static void writeMap(JsonGenerator jg, String name, Map map) throws IOException {
-    jg.writeObjectFieldStart(name);
-    Set<Map.Entry> entries = map.entrySet();
-    for (Map.Entry entry : entries) {
-      writeObjectField(jg, entry.getKey().toString(), entry.getValue());
-    }
-    jg.writeEndObject();
-  }
-
-  private static void writeList(JsonGenerator jg, String name, List list) throws IOException {
-    jg.writeArrayFieldStart(name);
-    for (Object item : list) {
-      jg.writeObject(item);
-    }
-    jg.writeEndArray();
-  }
-}

ReactAndroid/src/main/java/com/facebook/react/bridge/JsonWriter.java

@@ -0,0 +1,218 @@
+/**
+ * Copyright (c) 2015-present, Facebook, Inc.
+ * All rights reserved.
+ *
+ * This source code is licensed under the BSD-style license found in the
+ * LICENSE file in the root directory of this source tree. An additional grant
+ * of patent rights can be found in the PATENTS file in the same directory.
+ */
+
+package com.facebook.react.bridge;
+
+import java.io.Closeable;
+import java.io.IOException;
+import java.io.Writer;
+import java.util.ArrayDeque;
+import java.util.Deque;
+
+/**
+ * Simple Json generator that does no validation.
+ */
+public class JsonWriter implements Closeable {
+  private final Writer mWriter;
+  private final Deque<Scope> mScopes;
+
+  public JsonWriter(Writer writer) {
+    mWriter = writer;
+    mScopes = new ArrayDeque<>();
+  }
+
+  public JsonWriter beginArray() throws IOException {
+    open(Scope.EMPTY_ARRAY, '[');
+    return this;
+  }
+
+  public JsonWriter endArray() throws IOException {
+    close(']');
+    return this;
+  }
+
+  public JsonWriter beginObject() throws IOException {
+    open(Scope.EMPTY_OBJECT, '{');
+    return this;
+  }
+
+  public JsonWriter endObject() throws IOException {
+    close('}');
+    return this;
+  }
+
+  public JsonWriter name(String name) throws IOException {
+    if (name == null) {
+      throw new NullPointerException("name can not be null");
+    }
+    beforeName();
+    string(name);
+    mWriter.write(':');
+    return this;
+  }
+
+  public JsonWriter value(String value) throws IOException {
+    if (value == null) {
+      return nullValue();
+    }
+    beforeValue();
+    string(value);
+    return this;
+  }
+
+  public JsonWriter nullValue() throws IOException {
+    beforeValue();
+    mWriter.write("null");
+    return this;
+  }
+
+  public JsonWriter rawValue(String json) throws IOException {
+    beforeValue();
+    mWriter.write(json);
+    return this;
+  }
+
+  public JsonWriter value(boolean value) throws IOException {
+    beforeValue();
+    mWriter.write(value ? "true" : "false");
+    return this;
+  }
+
+  public JsonWriter value(double value) throws IOException {
+    beforeValue();
+    mWriter.append(Double.toString(value));
+    return this;
+  }
+
+  public JsonWriter value(long value) throws IOException {
+    beforeValue();
+    mWriter.write(Long.toString(value));
+    return this;
+  }
+
+  public JsonWriter value(Number value) throws IOException {
+    if (value == null) {
+      return nullValue();
+    }
+    beforeValue();
+    mWriter.append(value.toString());
+    return this;
+  }
+
+  @Override
+  public void close() throws IOException {
+    mWriter.close();
+  }
+
+  private void beforeValue() throws IOException {
+    Scope scope = mScopes.peek();
+    switch (scope) {
+      case EMPTY_ARRAY:
+        replace(Scope.ARRAY);
+        break;
+      case EMPTY_OBJECT:
+        throw new IllegalArgumentException(Scope.EMPTY_OBJECT.name());
+      case ARRAY:
+        mWriter.write(',');
+        break;
+      case OBJECT:
+        break;
+      default:
+        throw new IllegalStateException("Unknown scope: " + scope);
+    }
+  }
+
+  private void beforeName() throws IOException {
+    Scope scope = mScopes.peek();
+    switch (scope) {
+      case EMPTY_ARRAY:
+      case ARRAY:
+        throw new IllegalStateException("name not allowed in array");
+      case EMPTY_OBJECT:
+        replace(Scope.OBJECT);
+        break;
+      case OBJECT:
+        mWriter.write(',');
+        break;
+      default:
+        throw new IllegalStateException("Unknown scope: " + scope);
+    }
+  }
+
+  private void open(Scope scope, char bracket) throws IOException {
+    mScopes.push(scope);
+    mWriter.write(bracket);
+  }
+
+  private void close(char bracket) throws IOException {
+    mScopes.pop();
+    mWriter.write(bracket);
+  }
+
+  private void string(String string) throws IOException {
+    mWriter.write('"');
+    for (int i = 0, length = string.length(); i < length; i++) {
+      char c = string.charAt(i);
+      switch (c) {
+        case '\t':
+          mWriter.write("\\t");
+          break;
+
+        case '\b':
+          mWriter.write("\\b");
+          break;
+
+        case '\n':
+          mWriter.write("\\n");
+          break;
+
+        case '\r':
+          mWriter.write("\\r");
+          break;
+
+        case '\f':
+          mWriter.write("\\f");
+          break;
+
+        case '"':
+        case '\\':
+          mWriter.write('\\');
+          mWriter.write(c);
+          break;
+
+        case '\u2028':
+        case '\u2029':
+          mWriter.write(String.format("\\u%04x", (int) c));
+          break;
+
+        default:
+          if (c <= 0x1F) {
+            mWriter.write(String.format("\\u%04x", (int) c));
+          } else {
+            mWriter.write(c);
+          }
+          break;
+      }
+
+    }
+    mWriter.write('"');
+  }
+
+  private void replace(Scope scope) {
+    mScopes.pop();
+    mScopes.push(scope);
+  }
+
+  private enum Scope {
+    EMPTY_OBJECT,
+    OBJECT,
+    EMPTY_ARRAY,
+    ARRAY
+  }
+}

ReactAndroid/src/main/java/com/facebook/react/bridge/JsonWriterHelper.java

@@ -0,0 +1,60 @@
+/**
+ * Copyright (c) 2015-present, Facebook, Inc.
+ * All rights reserved.
+ *
+ * This source code is licensed under the BSD-style license found in the
+ * LICENSE file in the root directory of this source tree. An additional grant
+ * of patent rights can be found in the PATENTS file in the same directory.
+ */
+
+package com.facebook.react.bridge;
+
+import java.io.IOException;
+import java.util.List;
+import java.util.Map;
+
+/**
+ * Helper for generating JSON for lists and maps.
+ */
+class JsonWriterHelper {
+  public static void value(JsonWriter writer, Object value) throws IOException {
+    if (value instanceof Map) {
+      mapValue(writer, (Map) value);
+    } else if (value instanceof List) {
+      listValue(writer, (List) value);
+    } else {
+      objectValue(writer, value);
+    }
+  }
+
+  private static void mapValue(JsonWriter writer, Map<?, ?> map) throws IOException {
+    writer.beginObject();
+    for (Map.Entry entry : map.entrySet()) {
+      writer.name(entry.getKey().toString());
+      value(writer, entry.getValue());
+    }
+    writer.endObject();
+  }
+
+  private static void listValue(JsonWriter writer, List<?> list) throws IOException {
+    writer.beginArray();
+    for (Object item : list) {
+      objectValue(writer, item);
+    }
+    writer.endArray();
+  }
+
+  private static void objectValue(JsonWriter writer, Object value) throws IOException {
+    if (value == null) {
+      writer.nullValue();
+    } else if (value instanceof String) {
+      writer.value((String) value);
+    } else if (value instanceof Number) {
+      writer.value((Number) value);
+    } else if (value instanceof Boolean) {
+      writer.value((Boolean) value);
+    } else {
+      throw new IllegalArgumentException("Unknown value: " + value);
+    }
+  }
+}

ReactAndroid/src/main/java/com/facebook/react/bridge/NativeModule.java

@@ -12,8 +12,6 @@ package com.facebook.react.bridge;
 import java.io.IOException;
 import java.util.Map;
 
-import com.fasterxml.jackson.core.JsonGenerator;
-
 /**
  * A native module whose API can be provided to JS catalyst instances.  {@link NativeModule}s whose
  * implementation is written in Java should extend {@link BaseJavaModule} or {@link
@@ -42,7 +40,7 @@ public interface NativeModule {
    * Append a field which represents the constants this module exports
    * to JS.  If no constants are exported this should do nothing.
    */
-  void writeConstantsField(JsonGenerator jg, String fieldName) throws IOException;
+  void writeConstantsField(JsonWriter writer, String fieldName) throws IOException;
 
   /**
    * This is called at the end of {@link CatalystApplicationFragment#createCatalystInstance()}

ReactAndroid/src/main/java/com/facebook/react/bridge/NativeModuleRegistry.java

@@ -20,8 +20,6 @@ import com.facebook.react.common.MapBuilder;
 import com.facebook.infer.annotation.Assertions;
 import com.facebook.systrace.Systrace;
 
-import com.fasterxml.jackson.core.JsonGenerator;
-
 /**
   * A set of Java APIs to expose to a particular JavaScript instance.
   */
@@ -64,27 +62,27 @@ public class NativeModuleRegistry {
     definition.call(catalystInstance, executorToken, methodId, parameters);
   }
 
-  /* package */ void writeModuleDescriptions(JsonGenerator jg) throws IOException {
+  /* package */ void writeModuleDescriptions(JsonWriter writer) throws IOException {
     Systrace.beginSection(Systrace.TRACE_TAG_REACT_JAVA_BRIDGE, "CreateJSON");
     try {
-      jg.writeStartObject();
+      writer.beginObject();
       for (ModuleDefinition moduleDef : mModuleTable) {
-        jg.writeObjectFieldStart(moduleDef.name);
+        writer.name(moduleDef.name).beginObject();
-        jg.writeNumberField("moduleID", moduleDef.id);
+        writer.name("moduleID").value(moduleDef.id);
-        jg.writeBooleanField("supportsWebWorkers", moduleDef.target.supportsWebWorkers());
+        writer.name("supportsWebWorkers").value(moduleDef.target.supportsWebWorkers());
-        jg.writeObjectFieldStart("methods");
+        writer.name("methods").beginObject();
         for (int i = 0; i < moduleDef.methods.size(); i++) {
           MethodRegistration method = moduleDef.methods.get(i);
-          jg.writeObjectFieldStart(method.name);
+          writer.name(method.name).beginObject();
-          jg.writeNumberField("methodID", i);
+          writer.name("methodID").value(i);
-          jg.writeStringField("type", method.method.getType());
+          writer.name("type").value(method.method.getType());
-          jg.writeEndObject();
+          writer.endObject();
         }
-        jg.writeEndObject();
+        writer.endObject();
-        moduleDef.target.writeConstantsField(jg, "constants");
+        moduleDef.target.writeConstantsField(writer, "constants");
-        jg.writeEndObject();
+        writer.endObject();
       }
-      jg.writeEndObject();
+      writer.endObject();
     } finally {
       Systrace.endSection(Systrace.TRACE_TAG_REACT_JAVA_BRIDGE);
     }

ReactAndroid/src/test/java/com/facebook/react/bridge/BUCK

@@ -8,12 +8,12 @@ android_library(
   name = 'testhelpers',
   srcs = glob(['*.java'], excludes = STANDARD_TEST_SRCS),
   deps = [
-    react_native_target('java/com/facebook/react/bridge:bridge'),
-    react_native_target('java/com/facebook/react/uimanager:uimanager'),
     react_native_dep('third-party/java/mockito:mockito'),
     react_native_dep('third-party/java/robolectric3/robolectric:robolectric'),
+    react_native_target('java/com/facebook/react/bridge:bridge'),
+    react_native_target('java/com/facebook/react/uimanager:uimanager'),
     react_native_tests_target('java/org/mockito/configuration:configuration'),
-],
+  ],
   visibility = [
     'PUBLIC'
   ],
@@ -26,19 +26,18 @@ robolectric3_test(
   srcs = glob(STANDARD_TEST_SRCS),
   deps = [
     ':testhelpers',
-    react_native_target('java/com/facebook/react/bridge:bridge'),
+    react_native_dep('libraries/fbcore/src/test/java/com/facebook/powermock:powermock'),
-    react_native_target('java/com/facebook/react/common:common'),
+    react_native_dep('libraries/soloader/java/com/facebook/soloader:soloader'),
-    react_native_target('java/com/facebook/react/uimanager:uimanager'),
-
-    react_native_dep('third-party/java/robolectric3/robolectric:robolectric'),
     react_native_dep('third-party/java/fest:fest'),
-    react_native_dep('third-party/java/junit:junit'),
-    react_native_dep('third-party/java/mockito:mockito'),
     react_native_dep('third-party/java/jackson:core'),
     react_native_dep('third-party/java/jackson:jackson'),
     react_native_dep('third-party/java/jsr-305:jsr-305'),
-    react_native_dep('libraries/fbcore/src/test/java/com/facebook/powermock:powermock'),
+    react_native_dep('third-party/java/junit:junit'),
-    react_native_dep('libraries/soloader/java/com/facebook/soloader:soloader'),
+    react_native_dep('third-party/java/mockito:mockito'),
+    react_native_dep('third-party/java/robolectric3/robolectric:robolectric'),
+    react_native_target('java/com/facebook/react/bridge:bridge'),
+    react_native_target('java/com/facebook/react/common:common'),
+    react_native_target('java/com/facebook/react/uimanager:uimanager'),
   ],
   visibility = [
     'PUBLIC'

ReactAndroid/src/test/java/com/facebook/react/bridge/JavaScriptModuleConfigTest.java

@@ -12,8 +12,6 @@ package com.facebook.react.bridge;
 import java.io.IOException;
 import java.io.StringWriter;
 
-import com.fasterxml.jackson.core.JsonFactory;
-import com.fasterxml.jackson.core.JsonGenerator;
 import com.fasterxml.jackson.databind.JsonNode;
 import com.fasterxml.jackson.databind.ObjectMapper;
 import org.junit.Test;
@@ -82,12 +80,11 @@ public class JavaScriptModuleConfigTest {
 
   private static String getModuleDescriptions(JavaScriptModulesConfig jsModulesConfig)
       throws IOException {
-    JsonFactory jsonFactory = new JsonFactory();
+    StringWriter stringWriter = new StringWriter();
-    StringWriter writer = new StringWriter();
+    JsonWriter writer = new JsonWriter(stringWriter);
-    JsonGenerator jg = jsonFactory.createGenerator(writer);
+    jsModulesConfig.writeModuleDescriptions(writer);
-    jsModulesConfig.writeModuleDescriptions(jg);
+    writer.close();
-    jg.close();
+    return stringWriter.getBuffer().toString();
-    return writer.getBuffer().toString();
   }
 
   private JsonNode parse(String json) throws Exception {

ReactAndroid/src/test/java/com/facebook/react/bridge/JsonWriterTest.java

@@ -0,0 +1,100 @@
+/**
+ * Copyright (c) 2015-present, Facebook, Inc.
+ * All rights reserved.
+ *
+ * This source code is licensed under the BSD-style license found in the
+ * LICENSE file in the root directory of this source tree. An additional grant
+ * of patent rights can be found in the PATENTS file in the same directory.
+ */
+
+package com.facebook.react.bridge;
+
+import java.io.IOException;
+import java.io.StringWriter;
+
+import org.junit.Test;
+
+import static org.fest.assertions.api.Assertions.assertThat;
+
+public class JsonWriterTest {
+  private final StringWriter mStringWriter;
+  private final JsonWriter mWriter;
+
+  public JsonWriterTest() {
+    mStringWriter = new StringWriter();
+    mWriter = new JsonWriter(mStringWriter);
+  }
+
+  @Test
+  public void emptyObject() throws IOException {
+    mWriter.beginObject();
+    mWriter.endObject();
+    verify("{}");
+  }
+
+  @Test
+  public void emptyNestedObject() throws IOException {
+    mWriter.beginObject();
+    mWriter.beginObject();
+    mWriter.endObject();
+    mWriter.endObject();
+    verify("{{}}");
+  }
+
+  @Test
+  public void emptyArray() throws IOException {
+    mWriter.beginArray();
+    mWriter.endArray();
+    verify("[]");
+  }
+
+  @Test
+  public void emptyNestedArray() throws IOException {
+    mWriter.beginArray();
+    mWriter.beginArray();
+    mWriter.endArray();
+    mWriter.endArray();
+    verify("[[]]");
+  }
+
+  @Test
+  public void smallObject() throws IOException {
+    mWriter.beginObject();
+    mWriter.name("hello").value(true);
+    mWriter.name("hello_again").value("hi!");
+    mWriter.endObject();
+    verify("{\"hello\":true,\"hello_again\":\"hi!\"}");
+  }
+
+  @Test
+  public void smallArray() throws IOException {
+    mWriter.beginArray();
+    mWriter.value(true);
+    mWriter.value(1);
+    mWriter.value(1.0);
+    mWriter.value("hi!");
+    mWriter.endArray();
+    verify("[true,1,1.0,\"hi!\"]");
+  }
+
+  @Test
+  public void string() throws IOException {
+    mWriter.beginObject();
+    mWriter.name("string").value("hello!");
+    mWriter.endObject();
+    verify("{\"string\":\"hello!\"}");
+  }
+
+  @Test
+  public void complexString() throws IOException {
+    mWriter.beginObject();
+    mWriter.name("string").value("\t\uD83D\uDCA9");
+    mWriter.endObject();
+    verify("{\"string\":\"\\t\uD83D\uDCA9\"}");
+  }
+
+  private void verify(String expected) throws IOException {
+    mWriter.close();
+    assertThat(mStringWriter.getBuffer().toString()).isEqualTo(expected);
+  }
+}

ReactAndroid/src/test/java/com/facebook/react/bridge/NativeModuleRegistryTest.java

@@ -20,8 +20,6 @@ import java.util.Map;
 
 import com.facebook.react.common.MapBuilder;
 
-import com.fasterxml.jackson.core.JsonFactory;
-import com.fasterxml.jackson.core.JsonGenerator;
 import com.fasterxml.jackson.databind.JsonNode;
 import com.fasterxml.jackson.databind.ObjectMapper;
 import com.fasterxml.jackson.databind.node.TextNode;
@@ -189,12 +187,11 @@ public class NativeModuleRegistryTest {
 
   private static String getModuleDescriptions(NativeModuleRegistry registry)
       throws IOException {
-    JsonFactory jsonFactory = new JsonFactory();
+    StringWriter stringWriter = new StringWriter();
-    StringWriter writer = new StringWriter();
+    JsonWriter writer = new JsonWriter(stringWriter);
-    JsonGenerator jg = jsonFactory.createGenerator(writer);
+    registry.writeModuleDescriptions(writer);
-    registry.writeModuleDescriptions(jg);
+    writer.close();
-    jg.close();
+    return stringWriter.getBuffer().toString();
-    return writer.getBuffer().toString();
   }
 
   private static class MethodsModule extends BaseJavaModule {