Retrofit LocalJsonClient

gistfile1.java

import android.annotation.SuppressLint;
import android.content.Context;
import android.util.Log;

import retrofit.client.Client;
import retrofit.client.Header;
import retrofit.client.Request;
import retrofit.client.Response;
import retrofit.mime.TypedInput;

import java.io.IOException;
import java.io.InputStream;
import java.net.URL;
import java.net.URLConnection;
import java.util.ArrayList;

@SuppressLint("DefaultLocale")
public class LocalJsonClient implements Client {
    private Context context;

    private String scenario = null;

    public LocalJsonClient(Context ctx) {
        this.context = ctx;
    }

    public void setScenario(String scenario) {
        this.scenario = scenario;
    }

    @Override
    public Response execute(Request request) throws IOException {
        URL requestedUrl = new URL(request.getUrl());
        String requestedMethod = request.getMethod();

        String prefix = "";
        if (this.scenario != null) {
            prefix = scenario + "_";
        }

        String fileName = (prefix + requestedMethod + requestedUrl.getPath()).replace("/", "_");
        fileName = fileName.toLowerCase();

        int resourceId = context.getResources().getIdentifier(fileName, "raw",
                context.getPackageName());

        if (resourceId == 0) {
            Log.wtf("YourTag", "Could not find res/raw/" + fileName + ".json");
            throw new IOException("Could not find res/raw/" + fileName + ".json");
        }

        InputStream inputStream = context.getResources().openRawResource(resourceId);

        String mimeType = URLConnection.guessContentTypeFromStream(inputStream);
        if (mimeType == null) {
            mimeType = "application/json";
        }

        TypedInput body = new TypedInputStream(mimeType, inputStream.available(), inputStream);
        return new Response(request.getUrl(), 200, "Content from res/raw/" + fileName, new ArrayList<Header>(), body);
    }

    private static class TypedInputStream implements TypedInput {
        private final String mimeType;
        private final long length;
        private final InputStream stream;

        private TypedInputStream(String mimeType, long length, InputStream stream) {
            this.mimeType = mimeType;
            this.length = length;
            this.stream = stream;
        }

        @Override
        public String mimeType() {
            return mimeType;
        }

        @Override
        public long length() {
            return length;
        }

        @Override
        public InputStream in() throws IOException {
            return stream;
        }
    }
}

gistfile2.md

A Retrofit Client that reads JSON files from disk and returns them as the response (to be handled by GSON). Make sure the context you pass is from the instrumentation app and put your JSON files in res/raw in the instrumentation project. Inspired by Ruby's vcr gem.

A GET request to /articles will look for the JSON file res/raw/get_articles.json, a POST request to /articles/123/ will look for the JSON file res/raw/post_articles_123.json, etc.

We use setScenario() if we want to test alternate responses so that a failed login POST to /login will read from res/raw/failed_login_post_login.json (and the happy path can use post_login.json).

@dannyroa: You can supply it to RestAdapter.Builder with your own Client implementation, such as this one.

@f2prateek sorry for the 3 month late reply - yes that is correct about other data formats. I actually use the above code as-is with an XML route in the same app. #guessContentTypeFromStream() does the magic of setting the right mimetype.

No reason on raw vs assets - just where I happened to put them :)

In Retrofit 1.5.1 only work with this Response construct

return new Response(path, 200, "Content from res/raw/" + fileName,
new ArrayList

(), body);

Thanks

Since Retrofit 1.6.1

@@ -59,12 +63,14 @@ public class LocalJsonClient implements Client {
         }

         TypedInput body = new TypedInputStream(mimeType, inputStream.available(), inputStream);
-        return new Response(200, "Content from res/raw/" + fileName, new ArrayList<Header>(), body);
+        return new Response(request.getUrl(), 200, "Content from res/raw/" + fileName, new ArrayList<Header>(), body);

@creativepsyco - hey thanks. I've updated the code.

Can you implement this in Retrofit 2.0?

Below is a link to a gist for an OkHttp3 interceptor, which can be added to an OkHttpClient via OkHttpClient.Builder().addInterceptor() to achieve the response mocking in OkHttp3.

https://gist.github.com/mbunyard/78311b25aaba8b9bfec380f66c868644

Does this work for retrofit 2.0 and how do you use this setup?