A Mock server built in Java. Add your expectations in Java.

NanoMock.java

package se.atg.nanomock;

import com.sun.net.httpserver.Headers;
import com.sun.net.httpserver.HttpContext;
import com.sun.net.httpserver.HttpExchange;
import com.sun.net.httpserver.HttpServer;

import java.io.IOException;
import java.io.OutputStream;
import java.net.InetSocketAddress;
import java.util.List;
import java.util.Map;
import java.util.Set;

public class NanoMockServer {

    private static final int THREADS = 0;
    private static final int PORT = 8090;

    public static void main(String[] args) throws IOException {
        long startTime = System.currentTimeMillis();

        new NanoMockServer().run(HttpServer.create(new InetSocketAddress(PORT), THREADS));

        System.out.println(String.format("Server started in %d ms", (System.currentTimeMillis() - startTime)));
    }

    private void run(HttpServer httpServer) {
        createRootContext(httpServer);
        httpServer.start();
    }

    private void createRootContext(HttpServer httpServer) {
        HttpContext context = httpServer.createContext("/");
        context.setHandler(httpExchange -> {
            String payload = getPayload(httpExchange);
            httpExchange.sendResponseHeaders(200, payload.getBytes().length);
            final OutputStream output = httpExchange.getResponseBody();
            output.write(payload.getBytes());
            output.flush();
            httpExchange.close();
        });
    }

    private String getPayload(HttpExchange httpExchange) {
        return "URI: '" +
                httpExchange.getRequestURI() +
                "'\n" +
                "Method: " +
                httpExchange.getRequestMethod() +
                "\nHeaders:\n" +
                getHeaders(httpExchange.getRequestHeaders())
                ;
    }

    private String getHeaders(Headers requestHeaders) {
        StringBuilder result = new StringBuilder();
        Set<Map.Entry<String, List<String>>> entries = requestHeaders.entrySet();
        for (Map.Entry<String, List<String>> entry : entries) {
            result.append(entry.getKey());
            result.append(": ");
            result.append(String.join(",", entry.getValue()));
            result.append("\n");
        }
        return result.toString();
    }

}