A simple Google Mock example

[Ivan Enzhaev]

Hello!

I want to run this example: http://blog.divebomb.org/2011/07/my-first-c-cmake-googletest-and-googlemock/

But I see the text:

../HtmlParser_gtests/main.cpp:19: Failure

Actual function call count doesn't match EXPECT_CALL(mock, getUrlAsString("http://example.net"))...

         Expected: to be called once

         Actual: never called - unsatisfied and active

This are all files:

main.cpp

[code]

#include <string>

#include <vector>

#include <gtest/gtest.h>

#include <gmock/gmock.h>

#include "HttpFetch.h"

#include "HtmlParser.h"

using ::testing::Return;

class HttpFetchMock : public HttpFetch {

public:

    MOCK_CONST_METHOD1( getUrlAsString, std::string( const std::string& ) );

};

TEST(HtmlParser, NoData) {

    char *html;

    HttpFetchMock mock;

    HtmlParser parser(mock);

    EXPECT_CALL(mock, getUrlAsString("http://example.net"))

        .WillOnce(Return(std::string(html)));

    std::vector<std::string> links = parser.getAllLinks("http://example.net");

    EXPECT_EQ(0, links.size());

}

int main( int argc, char *argv[] ) {

    ::testing::InitGoogleMock( &argc, argv );

    return RUN_ALL_TESTS( );

}

[/code]

HtmlParser.h

[code]

#ifndef HTMLPARSER_H

#define HTMLPARSER_H

#include <string>

#include <vector>

#include "HttpFetch.h"

class HtmlParser {

public:

    HtmlParser( const HttpFetch &http ) : m_http( http ) {

    }

    std::vector<std::string> getAllLinks( const std::string &url ) const {

        // TODO

        return std::vector<std::string>();

    }

private:

    HttpFetch m_http;

};

#endif // HTMLPARSER_H

[/code]

HttpFetch.h

[code]

#ifndef HTTPFETCH_H

#define HTTPFETCH_H

#include <string>

class HttpFetch {

public:

    virtual ~HttpFetch( ) {

    }

    virtual std::string getUrlAsString( const std::string &url ) const {

        // TODO

        return std::string( );

    }

};

#endif // HTTPFETCH_H

[/code]

[Keith Ray]

In the code you published in this email, there is no code calling "getUrlAsString."

In the code published in "my-first-c-cmake-googletest-and-googlemock" there is no code calling "GetUriAsString".

That webpage maybe using a "mock-first" TDD example: first you write a failing test, then you make the test pass. In this case, the test is failing because the mocked method is never called. 

I think this would be a bad example of TDD. In TDD, I don't write tests that fail because a method isn't called. I write tests that fail because code doesn't yet exist to create the result or state expected by the test.

--
C. Keith Ray
* (650) 539-4729

* https://www.dropbox.com/s/mpoefyt9bz1yoxx/keith_ray_resume.pdf

* http://agilesolutionspace.blogspot.com/

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[Ivan Enzhaev]

Sorry for my English in advance.

What does this mean? "In the code you published in this email, there is no code calling "getUrlAsString.""

I have this method in the class HttpFetch:

virtual std::string getUrlAsString( const std::string &url ) const {

        // TODO

        return std::string( );

}

It returns empty string.

Please, see this code:

TEST(HtmlParser, NoData) {

    char *html;

    HttpFetchMock mock;
    HtmlParser parser(mock);

    EXPECT_CALL(mock, getUrlAsString("http://example.net"))
        .WillOnce(Return(std::string(html)));
}

class Mock has a method called "getUrlAsString". This string ".WillOnce" means that we will call this method one time. This string "Return(std::string(html)" means that this method return empty string.

[Billy Donahue]

On Thu, May 29, 2014 at 12:23 AM, Ivan Enzhaev <8obse...@gmail.com> wrote:

Sorry for my English in advance.

What does this mean? "In the code you published in this email, there is no code calling "getUrlAsString.""

I have this method in the class HttpFetch:

virtual std::string getUrlAsString( const std::string &url ) const {

        // TODO

        return std::string( );

}

It returns empty string.

Please, see this code:

TEST(HtmlParser, NoData) {



    char *html;



    HttpFetchMock mock;


    HtmlParser parser(mock);



    EXPECT_CALL(mock, getUrlAsString("http://example.net"))


        .WillOnce(Return(std::string(html)));


}

class Mock has a method called "getUrlAsString". This string ".WillOnce" means that we will call this method one time.

That's setting up an expectation that getUrlAsString will be called, but Keith is correct that there is no code that actually calls getUrlAsString here.

 

This string "Return(std::string(html)" means that this method return empty string.

Not quite. The char* html is never initialized, so there's no telling what string will be returned, if any.

 

To view this discussion on the web visit https://groups.google.com/d/msgid/googlemock/CAPxskvFwF0f8invPV4_DLFWGTD5aD4mPvbB42Xz81w4OqXvbgg%40mail.gmail.com.

[Ivan Enzhaev]

It is crashed on the string: EXPECT_STREQ("http://example.net/index.html", links[0].c_str());

On Thu, May 29, 2014 at 12:48 PM, Ivan Enzhaev <8obse...@gmail.com> wrote:

Now I see this text and my application is crashed:

[==========] Running 1 test from 1 test case.

[----------] Global test environment set-up.

[----------] 1 test from HtmlParser

[ RUN      ] HtmlParser.OneLink

../HtmlParser_gtests/main.cpp:28: Failure

Value of: links.size()

  Actual: 0

Expected: 1

The program has unexpectedly finished.

#include <string>

#include <vector>

#include <gtest/gtest.h>

#include <gmock/gmock.h>

#include "HttpFetch.h"

#include "HtmlParser.h"

using ::testing::Return;

class HttpFetchMock : public HttpFetch {

public:

    MOCK_CONST_METHOD1( getUrlAsString, std::string( const std::string& ) );

};

TEST(HtmlParser, OneLink) {

    char *html = "<html>"

            "<head></head>"

            "<body>"

            "<a href='/index.html'>index.html</a>"

            "</body>"

            "</html>";

    HttpFetchMock mock;

    HtmlParser parser( mock );

    EXPECT_CALL(mock, getUrlAsString("http://example.net"))

            .WillOnce(Return(std::string(html)));

    std::vector<std::string> links = parser.getAllLinks("http://example.net");

    EXPECT_EQ(1, links.size());

    EXPECT_STREQ("http://example.net/index.html", links[0].c_str());

}

//TEST(HtmlParser, NoData) {

//    char *html;

//    HttpFetchMock mock;

//    HtmlParser parser(mock);

//    EXPECT_CALL(mock, getUrlAsString("http://example.net"))

//        .WillOnce(Return(std::string("")));

//    std::vector<std::string> links = parser.getAllLinks("http://example.net");

//    EXPECT_EQ(0, links.size());

//}

[Ivan Enzhaev]

Now I see this text and my application is crashed:

[==========] Running 1 test from 1 test case.

[----------] Global test environment set-up.

[----------] 1 test from HtmlParser

[ RUN      ] HtmlParser.OneLink

../HtmlParser_gtests/main.cpp:28: Failure

Value of: links.size()

  Actual: 0

Expected: 1

The program has unexpectedly finished.

#include <string>

#include <vector>

#include <gtest/gtest.h>

#include <gmock/gmock.h>

#include "HttpFetch.h"

#include "HtmlParser.h"

using ::testing::Return;

class HttpFetchMock : public HttpFetch {

public:

    MOCK_CONST_METHOD1( getUrlAsString, std::string( const std::string& ) );

};

TEST(HtmlParser, OneLink) {

    char *html = "<html>"

            "<head></head>"

            "<body>"

            "<a href='/index.html'>index.html</a>"

            "</body>"

            "</html>";

    HttpFetchMock mock;

    HtmlParser parser( mock );

    EXPECT_CALL(mock, getUrlAsString("http://example.net"))

            .WillOnce(Return(std::string(html)));

    std::vector<std::string> links = parser.getAllLinks("http://example.net");

    EXPECT_EQ(1, links.size());

    EXPECT_STREQ("http://example.net/index.html", links[0].c_str());

}

//TEST(HtmlParser, NoData) {

//    char *html;

//    HttpFetchMock mock;

//    HtmlParser parser(mock);

//    EXPECT_CALL(mock, getUrlAsString("http://example.net"))

//        .WillOnce(Return(std::string("")));

//    std::vector<std::string> links = parser.getAllLinks("http://example.net");

//    EXPECT_EQ(0, links.size());

//}

int main( int argc, char *argv[] ) {

    ::testing::InitGoogleMock( &argc, argv );

    return RUN_ALL_TESTS( );

}

On Thu, May 29, 2014 at 9:01 AM, Billy Donahue <billyd...@google.com> wrote:

[Billy Donahue]

On Thu, May 29, 2014 at 4:53 AM, Ivan Enzhaev <8obse...@gmail.com> wrote:

It is crashed on the string: EXPECT_STREQ("http://example.net/index.html", links[0].c_str());

On Thu, May 29, 2014 at 12:48 PM, Ivan Enzhaev <8obse...@gmail.com> wrote:

Now I see this text and my application is crashed:

[==========] Running 1 test from 1 test case.

[----------] Global test environment set-up.

[----------] 1 test from HtmlParser

[ RUN      ] HtmlParser.OneLink

../HtmlParser_gtests/main.cpp:28: Failure

Value of: links.size()

  Actual: 0

Expected: 1

The program has unexpectedly finished.

You're accessing links[0] but links is empty.

You still haven't provided any code that calls mock.getUrlAsString.

[Ivan Enzhaev]

Please, give me a simple example about TDD in Google Mock. I can use GTest very well. But I want to use GMock too.

[Keith Ray]

I recommend going through this elearning:

https://elearning.industriallogic.com/gh/submit?Action=AlbumContentsAction&album=trw&devLanguage=Cpp

if you or your employer can pay for it.

Also, see this solution to a TDD exercise here:

https://elearning.industriallogic.com/gh/submit?Action=PageAction&album=before&path=before/testDrivenDevelopmentLab/phoneBillChallengeTask1Solution&devLanguage=Cpp

--
C. Keith Ray
* (650) 539-4729

* https://www.dropbox.com/s/mpoefyt9bz1yoxx/keith_ray_resume.pdf

* http://agilesolutionspace.blogspot.com/