Add MockHttpService (#492)

MockHttpService is used by discogapic generated unit tests. It operates similarly to the gapic MockService objects in that this mock service catches all incoming requests, and registers and returns expected responses/exceptions.

Author: andreamlin

gax-httpjson/src/main/java/com/google/api/gax/httpjson/ApiMethodDescriptor.java

@@ -31,17 +31,19 @@
 
 import com.google.api.client.http.HttpMethods;
 import com.google.api.core.BetaApi;
+import com.google.api.core.InternalApi;
 import com.google.auto.value.AutoValue;
+import com.google.common.collect.ImmutableSet;
 import com.google.gson.Gson;
 import com.google.gson.GsonBuilder;
 import com.google.gson.TypeAdapter;
 import com.google.gson.stream.JsonReader;
 import com.google.gson.stream.JsonWriter;
-import java.io.IOException;
 import java.io.Reader;
 import java.lang.reflect.Type;
 import java.util.HashSet;
 import java.util.Set;
+import javax.annotation.Nullable;
 
 @BetaApi
 @AutoValue
@@ -53,10 +55,12 @@ public abstract class ApiMethodDescriptor<RequestT, ResponseT> {
 
   public abstract Gson getRequestMarshaller();
 
+  @Nullable
   public abstract Gson getResponseMarshaller();
 
   public abstract Type getRequestType();
 
+  @Nullable
   public abstract Type getResponseType();
 
   // The name of the field in the RequestT that contains the resource name path.
@@ -78,46 +82,50 @@ public abstract class ApiMethodDescriptor<RequestT, ResponseT> {
   private static <RequestT, ResponseT> ApiMethodDescriptor<RequestT, ResponseT> create(
       String fullMethodName,
       RequestT requestInstance,
-      ResponseT responseInstance,
+      @Nullable ResponseT responseInstance,
       String endpointPathTemplate,
       String resourceNameField,
       Set<String> queryParams,
       HttpRequestFormatter<RequestT> httpRequestFormatter,
       String httpMethod) {
     final Type requestType = requestInstance.getClass();
-    final Type responseType = responseInstance.getClass();
     final Gson baseGson = new GsonBuilder().create();
 
     TypeAdapter requestTypeAdapter =
         new TypeAdapter<RequestT>() {
           @Override
-          public void write(JsonWriter out, RequestT value) throws IOException {
+          public void write(JsonWriter out, RequestT value) {
             baseGson.toJson(value, requestType, out);
           }
 
           @Override
-          public RequestT read(JsonReader in) throws IOException {
+          public RequestT read(JsonReader in) {
             return null;
           }
         };
 
-    TypeAdapter responseTypeAdapter =
-        new TypeAdapter<ResponseT>() {
-          @Override
-          public void write(JsonWriter out, ResponseT value) throws IOException {
-            throw new UnsupportedOperationException("Unnecessary operation.");
-          }
-
-          @Override
-          public ResponseT read(JsonReader in) throws IOException {
-            return baseGson.fromJson(in, responseType);
-          }
-        };
-
     Gson requestMarshaller =
         new GsonBuilder().registerTypeAdapter(requestType, requestTypeAdapter).create();
-    Gson responseMarshaller =
-        new GsonBuilder().registerTypeAdapter(responseType, responseTypeAdapter).create();
+
+    TypeAdapter responseTypeAdapter = null;
+    final Type responseType = responseInstance == null ? null : responseInstance.getClass();
+    Gson responseMarshaller = null;
+    if (responseInstance != null) {
+      responseTypeAdapter =
+          new TypeAdapter<ResponseT>() {
+            @Override
+            public void write(JsonWriter out, ResponseT value) {
+              baseGson.toJson(value, responseType, out);
+            }
+
+            @Override
+            public ResponseT read(JsonReader in) {
+              return baseGson.fromJson(in, responseType);
+            }
+          };
+      responseMarshaller =
+          new GsonBuilder().registerTypeAdapter(responseType, responseTypeAdapter).create();
+    }
 
     return new AutoValue_ApiMethodDescriptor<>(
         fullMethodName,
@@ -137,8 +145,9 @@ ResponseT parseResponse(Reader input) {
     return getResponseMarshaller().fromJson(input, getResponseType());
   }
 
-  void writeRequest(Appendable output, RequestT request) {
-    this.getRequestMarshaller().toJson(request, output);
+  @InternalApi
+  public void writeResponse(Appendable output, Class clazz, Object response) {
+    this.getResponseMarshaller().toJson(response, clazz, output);
   }
 
   void writeRequestBody(RequestT apiMessage, Appendable output) {
@@ -188,7 +197,7 @@ public Builder<RequestT, ResponseT> setResourceNameField(String resourceNameFiel
     }
 
     public Builder<RequestT, ResponseT> setQueryParams(Set<String> queryParams) {
-      this.queryParams = queryParams;
+      this.queryParams = ImmutableSet.copyOf(queryParams);
       return this;
     }
 

gax-httpjson/src/main/java/com/google/api/gax/httpjson/HttpRequestRunnable.java

@@ -40,6 +40,7 @@
 import com.google.api.client.json.JsonObjectParser;
 import com.google.api.client.util.GenericData;
 import com.google.api.core.SettableApiFuture;
+import com.google.api.gax.rpc.ApiException;
 import com.google.api.pathtemplate.PathTemplate;
 import com.google.auth.http.HttpCredentialsAdapter;
 import com.google.auth.oauth2.GoogleCredentials;
@@ -131,6 +132,16 @@ public void run() {
 
       HttpResponse httpResponse = httpRequest.execute();
 
+      if (methodDescriptor.getResponseType() == null) {
+        if (!httpResponse.isSuccessStatusCode()) {
+          throw new ApiException(
+              null,
+              HttpJsonStatusCode.of(httpResponse.getStatusCode(), httpResponse.getStatusMessage()),
+              false);
+        }
+        responseFuture.set(null);
+        return;
+      }
       ResponseT response =
           methodDescriptor.parseResponse(new InputStreamReader(httpResponse.getContent()));
       responseFuture.set(response);

gax-httpjson/src/main/java/com/google/api/gax/httpjson/InstantiatingHttpJsonChannelProvider.java

@@ -29,6 +29,7 @@
  */
 package com.google.api.gax.httpjson;
 
+import com.google.api.client.http.HttpTransport;
 import com.google.api.core.BetaApi;
 import com.google.api.core.InternalExtensionOnly;
 import com.google.api.gax.core.ExecutorProvider;
@@ -61,12 +62,25 @@ public final class InstantiatingHttpJsonChannelProvider implements TransportChan
   private final ExecutorProvider executorProvider;
   private final HeaderProvider headerProvider;
   private final String endpoint;
+  private final HttpTransport httpTransport;
 
   private InstantiatingHttpJsonChannelProvider(
       ExecutorProvider executorProvider, HeaderProvider headerProvider, String endpoint) {
     this.executorProvider = executorProvider;
     this.headerProvider = headerProvider;
     this.endpoint = endpoint;
+    this.httpTransport = null;
+  }
+
+  private InstantiatingHttpJsonChannelProvider(
+      ExecutorProvider executorProvider,
+      HeaderProvider headerProvider,
+      String endpoint,
+      HttpTransport httpTransport) {
+    this.executorProvider = executorProvider;
+    this.headerProvider = headerProvider;
+    this.endpoint = endpoint;
+    this.httpTransport = httpTransport;
   }
 
   @Override
@@ -129,6 +143,7 @@ private TransportChannel createChannel() throws IOException {
             .setEndpoint(endpoint)
             .setHeaderEnhancers(headerEnhancers)
             .setExecutor(executor)
+            .setHttpTransport(httpTransport)
             .build();
 
     return HttpJsonTransportChannel.newBuilder().setManagedChannel(channel).build();
@@ -156,13 +171,15 @@ public static final class Builder {
     private ExecutorProvider executorProvider;
     private HeaderProvider headerProvider;
     private String endpoint;
+    private HttpTransport httpTransport;
 
     private Builder() {}
 
     private Builder(InstantiatingHttpJsonChannelProvider provider) {
       this.executorProvider = provider.executorProvider;
       this.headerProvider = provider.headerProvider;
       this.endpoint = provider.endpoint;
+      this.httpTransport = provider.httpTransport;
     }
 
     /**
@@ -196,12 +213,19 @@ public Builder setEndpoint(String endpoint) {
       return this;
     }
 
+    /** Sets the HTTP transport to be used. */
+    public Builder setHttpTransport(HttpTransport httpTransport) {
+      this.httpTransport = httpTransport;
+      return this;
+    }
+
     public String getEndpoint() {
       return endpoint;
     }
 
     public InstantiatingHttpJsonChannelProvider build() {
-      return new InstantiatingHttpJsonChannelProvider(executorProvider, headerProvider, endpoint);
+      return new InstantiatingHttpJsonChannelProvider(
+          executorProvider, headerProvider, endpoint, httpTransport);
     }
   }
 }

gax-httpjson/src/main/java/com/google/api/gax/httpjson/ManagedHttpJsonChannel.java

@@ -35,6 +35,7 @@
 import com.google.api.client.json.jackson2.JacksonFactory;
 import com.google.api.core.ApiFuture;
 import com.google.api.core.BetaApi;
+import com.google.api.core.InternalApi;
 import com.google.api.core.SettableApiFuture;
 import com.google.api.gax.core.BackgroundResource;
 import com.google.common.base.Preconditions;
@@ -72,24 +73,31 @@ private ManagedHttpJsonChannel(
     this.httpTransport = httpTransport == null ? new NetHttpTransport() : httpTransport;
   }
 
+  @InternalApi
+  <ResponseT, RequestT> Runnable createRunnable(
+      final HttpJsonCallOptions callOptions,
+      final RequestT request,
+      final ApiMethodDescriptor<RequestT, ResponseT> methodDescriptor,
+      final SettableApiFuture<ResponseT> responseFuture) {
+    return HttpRequestRunnable.<RequestT, ResponseT>newBuilder()
+        .setApiFuture(responseFuture)
+        .setApiMethodDescriptor(methodDescriptor)
+        .setHeaderEnhancers(headerEnhancers)
+        .setHttpJsonCallOptions(callOptions)
+        .setHttpTransport(httpTransport)
+        .setJsonFactory(jsonFactory)
+        .setRequest(request)
+        .setEndpoint(endpoint)
+        .build();
+  }
+
   public <ResponseT, RequestT> ApiFuture<ResponseT> issueFutureUnaryCall(
       final HttpJsonCallOptions callOptions,
       final RequestT request,
       final ApiMethodDescriptor<RequestT, ResponseT> methodDescriptor) {
     final SettableApiFuture<ResponseT> responseFuture = SettableApiFuture.create();
-    HttpRequestRunnable<RequestT, ResponseT> runnable =
-        HttpRequestRunnable.<RequestT, ResponseT>newBuilder()
-            .setApiFuture(responseFuture)
-            .setApiMethodDescriptor(methodDescriptor)
-            .setHeaderEnhancers(headerEnhancers)
-            .setHttpJsonCallOptions(callOptions)
-            .setHttpTransport(httpTransport)
-            .setJsonFactory(jsonFactory)
-            .setRequest(request)
-            .setEndpoint(endpoint)
-            .build();
-
-    executor.execute(runnable);
+
+    executor.execute(createRunnable(callOptions, request, methodDescriptor, responseFuture));
 
     return responseFuture;
   }