carto
/
grpc


			
				
					
						
						
							123456789101112131415161718192021222324252627282930313233343536373839404142434445464748495051525354555657585960616263646566676869707172737475767778798081828384858687888990919293949596979899100101102103104105106107108109110111112113114115116117118119120121122123124125126127128129130131132133134135136137138139140141142143144145146147148149150151152153154155156157158159160161162163164165166167168169170171172173174175176177178179180181182183184185186187188189190191192193194195196197198199200201202203204205206
							<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "https://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<meta http-equiv="Content-Type" content="text/xhtml;charset=UTF-8"/>
<meta http-equiv="X-UA-Compatible" content="IE=9"/>
<meta name="generator" content="Doxygen 1.8.17"/>
<meta name="viewport" content="width=device-width, initial-scale=1"/>
<title>GRPC Objective-C: How to write unit tests for gRPC C client.</title>
<link href="tabs.css" rel="stylesheet" type="text/css"/>
<script type="text/javascript" src="jquery.js"></script>
<script type="text/javascript" src="dynsections.js"></script>
<link href="search/search.css" rel="stylesheet" type="text/css"/>
<script type="text/javascript" src="search/searchdata.js"></script>
<script type="text/javascript" src="search/search.js"></script>
<link href="doxygen.css" rel="stylesheet" type="text/css" />
</head>
<body>
<div id="top"><!-- do not remove this div, it is closed by doxygen! -->
<div id="titlearea">
<table cellspacing="0" cellpadding="0">
 <tbody>
 <tr style="height: 56px;">
  <td id="projectalign" style="padding-left: 0.5em;">
   <div id="projectname">GRPC Objective-C
   &#160;<span id="projectnumber">1.36.1</span>
   </div>
  </td>
 </tr>
 </tbody>
</table>
</div>
<!-- end header part -->
<!-- Generated by Doxygen 1.8.17 -->
<script type="text/javascript">
/* @license magnet:?xt=urn:btih:cf05388f2679ee054f2beb29a391d25f4e673ac3&amp;dn=gpl-2.0.txt GPL-v2 */
var searchBox = new SearchBox("searchBox", "search",false,'Search');
/* @license-end */
</script>
<script type="text/javascript" src="menudata.js"></script>
<script type="text/javascript" src="menu.js"></script>
<script type="text/javascript">
/* @license magnet:?xt=urn:btih:cf05388f2679ee054f2beb29a391d25f4e673ac3&amp;dn=gpl-2.0.txt GPL-v2 */
$(function() {
  initMenu('',true,false,'search.php','Search');
  $(document).ready(function() { init_search(); });
});
/* @license-end */</script>
<div id="main-nav"></div>
<!-- window showing the filter options -->
<div id="MSearchSelectWindow"
     onmouseover="return searchBox.OnSearchSelectShow()"
     onmouseout="return searchBox.OnSearchSelectHide()"
     onkeydown="return searchBox.OnSearchSelectKey(event)">
</div>

<!-- iframe showing the search results (closed by default) -->
<div id="MSearchResultsWindow">
<iframe src="javascript:void(0)" frameborder="0" 
        name="MSearchResults" id="MSearchResults">
</iframe>
</div>

</div><!-- top -->
<div class="PageDoc"><div class="header">
  <div class="headertitle">
<div class="title">How to write unit tests for gRPC C client. </div>  </div>
</div><!--header-->
<div class="contents">
<div class="textblock"><p>tl;dr: <a href="https://github.com/grpc/grpc/blob/master/test/cpp/end2end/mock_test.cc">Example code</a>.</p>
<p>To unit-test client-side logic via the synchronous API, gRPC provides a mocked Stub based on googletest(googlemock) that can be programmed upon and easily incorporated in the test code.</p>
<p>For instance, consider an EchoService like this:</p>
<div class="fragment"><div class="line">service EchoTestService {</div>
<div class="line">        rpc Echo(EchoRequest) returns (EchoResponse);</div>
<div class="line">        rpc BidiStream(stream EchoRequest) returns (stream EchoResponse);</div>
<div class="line">}</div>
</div><!-- fragment --><p>The code generated would look something like this:</p>
<div class="fragment"><div class="line"><span class="keyword">class </span>EchoTestService final {</div>
<div class="line">  <span class="keyword">public</span>:</div>
<div class="line">  <span class="keyword">class </span>StubInterface {</div>
<div class="line">    virtual ::grpc::Status Echo(::grpc::ClientContext* context, const ::grpc::testing::EchoRequest&amp; request, ::grpc::testing::EchoResponse* response) = 0;</div>
<div class="line">  …</div>
<div class="line">    std::unique_ptr&lt; ::grpc::ClientReaderWriterInterface&lt; ::grpc::testing::EchoRequest, ::grpc::testing::EchoResponse&gt;&gt; BidiStream(::grpc::ClientContext* context) {</div>
<div class="line">      <span class="keywordflow">return</span> std::unique_ptr&lt; ::grpc::ClientReaderWriterInterface&lt; ::grpc::testing::EchoRequest, ::grpc::testing::EchoResponse&gt;&gt;(BidiStreamRaw(context));</div>
<div class="line">    }</div>
<div class="line">  …</div>
<div class="line">    <span class="keyword">private</span>:</div>
<div class="line">    virtual ::grpc::ClientReaderWriterInterface&lt; ::grpc::testing::EchoRequest, ::grpc::testing::EchoResponse&gt;* BidiStreamRaw(::grpc::ClientContext* context) = 0;</div>
<div class="line">  …</div>
<div class="line">  } <span class="comment">// End StubInterface</span></div>
<div class="line">…</div>
<div class="line">} <span class="comment">// End EchoTestService</span></div>
</div><!-- fragment --><p>If we mock the StubInterface and set expectations on the pure-virtual methods we can test client-side logic without having to make any rpcs.</p>
<p>A mock for this StubInterface will look like this:</p>
<div class="fragment"><div class="line"><span class="keyword">class </span>MockEchoTestServiceStub : <span class="keyword">public</span> EchoTestService::StubInterface {</div>
<div class="line"> <span class="keyword">public</span>:</div>
<div class="line">  MOCK_METHOD3(Echo, ::grpc::Status(::grpc::ClientContext* context, const ::grpc::testing::EchoRequest&amp; request, ::grpc::testing::EchoResponse* response));</div>
<div class="line">  MOCK_METHOD1(BidiStreamRaw, ::grpc::ClientReaderWriterInterface&lt; ::grpc::testing::EchoRequest, ::grpc::testing::EchoResponse&gt;*(::grpc::ClientContext* context));</div>
<div class="line">};</div>
</div><!-- fragment --><p><b>Generating mock code:</b></p>
<p>Such a mock can be auto-generated by:</p>
<ol type="1">
<li>Setting flag(generate_mock_code=true) on grpc plugin for protoc, or</li>
</ol>
<ol type="1">
<li>Setting an attribute(generate_mocks) in your bazel rule.</li>
</ol>
<p>Protoc plugin flag:</p>
<div class="fragment"><div class="line">protoc -I . --grpc_out=generate_mock_code=true:. --plugin=protoc-gen-grpc=`which grpc_cpp_plugin` echo.proto</div>
</div><!-- fragment --><p>Bazel rule:</p>
<div class="fragment"><div class="line">grpc_proto_library(</div>
<div class="line">  name = <span class="stringliteral">&quot;echo_proto&quot;</span>,</div>
<div class="line">  srcs = [<span class="stringliteral">&quot;echo.proto&quot;</span>],</div>
<div class="line">  generate_mocks = <span class="keyword">True</span>,</div>
<div class="line">)</div>
</div><!-- fragment --><p>By adding such a flag now a header file <code>echo_mock.grpc.pb.h</code> containing the mocked stub will also be generated.</p>
<p>This header file can then be included in test files along with a gmock dependency.</p>
<p><b>Writing tests with mocked Stub.</b></p>
<p>Consider the following client a user might have:</p>
<div class="fragment"><div class="line"><span class="keyword">class </span>FakeClient {</div>
<div class="line"> <span class="keyword">public</span>:</div>
<div class="line">  <span class="keyword">explicit</span> FakeClient(EchoTestService::StubInterface* stub) : stub_(stub) {}</div>
<div class="line"> </div>
<div class="line">  <span class="keywordtype">void</span> DoEcho() {</div>
<div class="line">    ClientContext context;</div>
<div class="line">    EchoRequest request;</div>
<div class="line">    EchoResponse response;</div>
<div class="line">    request.set_message(<span class="stringliteral">&quot;hello world&quot;</span>);</div>
<div class="line">    Status s = stub_-&gt;Echo(&amp;context, request, &amp;response);</div>
<div class="line">    EXPECT_EQ(request.message(), response.message());</div>
<div class="line">    EXPECT_TRUE(s.ok());</div>
<div class="line">  }</div>
<div class="line"> </div>
<div class="line">  <span class="keywordtype">void</span> DoBidiStream() {</div>
<div class="line">    EchoRequest request;</div>
<div class="line">    EchoResponse response;</div>
<div class="line">    ClientContext context;</div>
<div class="line">    std::string msg(<span class="stringliteral">&quot;hello&quot;</span>);</div>
<div class="line"> </div>
<div class="line">    std::unique_ptr&lt;ClientReaderWriterInterface&lt;EchoRequest, EchoResponse&gt;&gt;</div>
<div class="line">        stream = stub_-&gt;BidiStream(&amp;context);</div>
<div class="line"> </div>
<div class="line">    request.set_message(msg  <span class="stringliteral">&quot;0&quot;</span>);</div>
<div class="line">    EXPECT_TRUE(stream-&gt;Write(request));</div>
<div class="line">    EXPECT_TRUE(stream-&gt;Read(&amp;response));</div>
<div class="line">    EXPECT_EQ(response.message(), request.message());</div>
<div class="line"> </div>
<div class="line">    request.set_message(msg  <span class="stringliteral">&quot;1&quot;</span>);</div>
<div class="line">    EXPECT_TRUE(stream-&gt;Write(request));</div>
<div class="line">    EXPECT_TRUE(stream-&gt;Read(&amp;response));</div>
<div class="line">    EXPECT_EQ(response.message(), request.message());</div>
<div class="line"> </div>
<div class="line">    request.set_message(msg  <span class="stringliteral">&quot;2&quot;</span>);</div>
<div class="line">    EXPECT_TRUE(stream-&gt;Write(request));</div>
<div class="line">    EXPECT_TRUE(stream-&gt;Read(&amp;response));</div>
<div class="line">    EXPECT_EQ(response.message(), request.message());</div>
<div class="line"> </div>
<div class="line">    stream-&gt;WritesDone();</div>
<div class="line">    EXPECT_FALSE(stream-&gt;Read(&amp;response));</div>
<div class="line"> </div>
<div class="line">    Status s = stream-&gt;Finish();</div>
<div class="line">    EXPECT_TRUE(s.ok());</div>
<div class="line">  }</div>
<div class="line"> </div>
<div class="line">  <span class="keywordtype">void</span> ResetStub(EchoTestService::StubInterface* stub) { stub_ = stub; }</div>
<div class="line"> </div>
<div class="line"> <span class="keyword">private</span>:</div>
<div class="line">  EchoTestService::StubInterface* stub_;</div>
<div class="line">};</div>
</div><!-- fragment --><p>A test could initialize this FakeClient with a mocked stub having set expectations on it:</p>
<p>Unary RPC:</p>
<div class="fragment"><div class="line">MockEchoTestServiceStub stub;</div>
<div class="line">EchoResponse resp;</div>
<div class="line">resp.set_message(<span class="stringliteral">&quot;hello world&quot;</span>);</div>
<div class="line">EXPECT_CALL(stub, Echo(_,_,_)).Times(AtLeast(1)).WillOnce(DoAll(SetArgPointee&lt;2&gt;(resp), Return(Status::OK)));</div>
<div class="line">FakeClient client(stub);</div>
<div class="line">client.DoEcho();</div>
</div><!-- fragment --><p>Streaming RPC:</p>
<div class="fragment"><div class="line">ACTION_P(copy, msg) {</div>
<div class="line">  arg0-&gt;set_message(msg-&gt;message());</div>
<div class="line">}</div>
<div class="line"> </div>
<div class="line"> </div>
<div class="line"><span class="keyword">auto</span> rw = <span class="keyword">new</span> MockClientReaderWriter&lt;EchoRequest, EchoResponse&gt;();</div>
<div class="line">EchoRequest msg;</div>
<div class="line">EXPECT_CALL(*rw, Write(_, _)).Times(3).WillRepeatedly(DoAll(SaveArg&lt;0&gt;(&amp;msg), Return(<span class="keyword">true</span>)));</div>
<div class="line">EXPECT_CALL(*rw, Read(_)).</div>
<div class="line">      WillOnce(DoAll(WithArg&lt;0&gt;(copy(&amp;msg)), Return(<span class="keyword">true</span>))).</div>
<div class="line">      WillOnce(DoAll(WithArg&lt;0&gt;(copy(&amp;msg)), Return(<span class="keyword">true</span>))).</div>
<div class="line">      WillOnce(DoAll(WithArg&lt;0&gt;(copy(&amp;msg)), Return(<span class="keyword">true</span>))).</div>
<div class="line">      WillOnce(Return(<span class="keyword">false</span>));</div>
<div class="line"> </div>
<div class="line">MockEchoTestServiceStub  stub;</div>
<div class="line">EXPECT_CALL(stub, BidiStreamRaw(_)).Times(AtLeast(1)).WillOnce(Return(rw));</div>
<div class="line"> </div>
<div class="line">FakeClient client(stub);</div>
<div class="line">client.DoBidiStream();</div>
</div><!-- fragment --> </div></div><!-- contents -->
</div><!-- PageDoc -->
<!-- start footer part -->
<hr class="footer"/><address class="footer"><small>
Generated on Wed Mar 3 2021 19:20:09 for GRPC Objective-C by &#160;<a href="http://www.doxygen.org/index.html">
<img class="footer" src="doxygen.png" alt="doxygen"/>
</a> 1.8.17
</small></address>
</body>
</html>