emscripten – Demens Deum

Simple Emscripten auto test with ChromeDriver

In this article, I will describe the implementation of running autotest for ChromeDriver of the Chrome browser, which runs the module autotest translated from C ++ using Emscripten, reads the console output and returns the result of the check.
First you need to install selenium, for python3-ubuntu this is done like this:


pip3 install selenium

Next, download ChromeDriver from the official site, put the chromedriver in / usr / local / bin for example, after which you can start implementing the autotest.
Below I will give the autotest code that launches the Chrome browser with the autotest page open on Emscripten, checks for the presence of the text “Window test succeded”:


import time
from selenium import webdriver
from selenium.webdriver.common.keys import Keys
from selenium.webdriver.common.desired_capabilities import DesiredCapabilities

capabilities = DesiredCapabilities.CHROME
capabilities['goog:loggingPrefs'] = { 'browser':'ALL' }
driver = webdriver.Chrome()
driver.get("http://localhost/windowInitializeTest/indexFullscreen.html")

time.sleep(2)

exitCode = 1

for entry in driver.get_log('browser'):
    if entry["source"] == "console-api":
        message = entry["message"]
        if "Window test succeded" in message:
            print("Test succeded")
            exitCode = 0

driver.close()
exit(exitCode)

Save the test as main.py and run python3 main.py

Building project with libraries Emscripten

In this article, I will describe the assembly of a project consisting of several libraries using Emscripten.
Emscripten does not currently support building shared libraries, so the first thing we do is translate all the libraries from Shared to Static. Emscripten works with its include files, so you need to solve the issue with the visibility of header files, I solved it by forwarding the symlink from the system directory to the Emscripten toolchain:


ln -s /usr/local/include/FlameSteelFramework $EMSDK/fastcomp/emscripten/system/include/FlameSteelFramework

If you use CMake, then you need to change SHARED-> STATIC in the CMakeLists.txt file of the add_library method. To build a library / application for further static linking, use the commands:


emcmake cmake .
emmake make

Next, you will need to build the main application indicating * .a library files at the linking stage. I could not indicate the relative path, the assembly completed correctly only after specifying the full paths in the CMakeLists.txt file:


elseif(EMSCRIPTEN)
target_link_libraries(${FSEGT_PROJECT_NAME} GL GLEW 
/home/demensdeum/Sources/cube-art-project-bootstrap/cube-art-project/sharedLib/libCubeArtProject.a 
/home/demensdeum/Sources/cube-art-project-bootstrap/FlameSteelFramework/FlameSteelEngineGameToolkitFSGL/libFlameSteelEngineGameToolkitFSGL.a 
/home/demensdeum/Sources/cube-art-project-bootstrap/FlameSteelFramework/FlameSteelEngineGameToolkit/libFlameSteelEngineGameToolkit.a 
/home/demensdeum/Sources/cube-art-project-bootstrap/FlameSteelFramework/FlameSteelCore/libFlameSteelCore.a 
/home/demensdeum/Sources/cube-art-project-bootstrap/FlameSteelFramework/FlameSteelBattleHorn/libFlameSteelBattleHorn.a 
/home/demensdeum/Sources/cube-art-project-bootstrap/FlameSteelFramework/FSGL/libFSGL.a 
/home/demensdeum/Sources/cube-art-project-bootstrap/FlameSteelFramework/FlameSteelCommonTraits/libFlameSteelCommonTraits.a)
else()

References

https://emscripten.org/docs/compiling/Building-Projects.html#using-libraries

Webassembly lost exceptions and regex troubles

Lost exceptions

An interesting feature of Emscripten, when starting a game loop through emscripten_set_main_loop, remember that exception handling must be re-added via try catch directly in the loop method, as runtime loses the try catch block from the outside.
The easiest way is to display the error text using the browser using javascript alert:


            catch (const std::exception &exc)
            {
                const char *errorText = exc.what();
                cout << "Exception: " << errorText << "; Stop execution" << endl;

                EM_ASM_(
                {
                    var errorText = UTF8ToString($0);
                    alert(errorText);

                }, errorText);

                abort();

Too complicated regexp

The regex implementation in std may throw an error_complexity exception if it finds the regex too complex. This happens in the current emscripten implementation, so I suggest you implement tests for parsing through regular intervals, or use third-party regex implementations.