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We aim to keep the code coverage of Electron high. We ask that all pull request not only pass all existing tests, but ideally also add new tests to cover changed code and new scenarios. Ensuring that we capture as many code paths and use cases of Electron as possible ensures that we all ship apps with fewer bugs.

This repository comes with linting rules for both JavaScript and C++ – as well as unit and integration tests. To learn more about Electron's coding style, please see the coding-style document.


To ensure that your JavaScript is in compliance with the Electron coding style, run npm run lint-js, which will run standard against both Electron itself as well as the unit tests. If you are using an editor with a plugin/addon system, you might want to use one of the many StandardJS addons to be informed of coding style violations before you ever commit them.

To run standard with parameters, run npm run lint-js -- followed by arguments you want passed to standard.

To ensure that your C++ is in compliance with the Electron coding style, run npm run lint-cpp, which runs a cpplint script. We recommend that you use clang-format and prepared a short tutorial.

There is not a lot of Python in this repository, but it too is governed by coding style rules. npm run lint-py will check all Python, using pylint to do so.

Unit Tests

If you are not using build-tools, ensure that that name you have configured for your local build of Electron is one of Testing, Release, Default, Debug, or you have set process.env.ELECTRON_OUT_DIR. Without these set, Electron will fail to perform some pre-testing steps.

To run all unit tests, run npm run test. The unit tests are an Electron app (surprise!) that can be found in the spec folder. Note that it has its own package.json and that its dependencies are therefore not defined in the top-level package.json.

To run only specific tests matching a pattern, run npm run test -- -g=PATTERN, replacing the PATTERN with a regex that matches the tests you would like to run. As an example: If you want to run only IPC tests, you would run npm run test -- -g ipc.

Testing on Windows 10 devices

Zusätzliche Schritte um den Unit-Test auszuführen:

  1. Visual Studio 2019 muss installiert sein.

  2. Node-Header müssen für Ihre Konfiguration kompiliert werden.

    ninja -C out\Testing third_party\electron_node:headers
  3. Die electron.lib muss als node.lib kopiert werden.

    cd out\Testing
    mkdir gen\node_headers\Release
    copy electron.lib gen\node_headers\Release\node.lib

Fehlende Schriften

Some Windows 10 devices do not ship with the Meiryo font installed, which may cause a font fallback test to fail. To install Meiryo:

  1. Drücken Sie die Window-Taste und suchen Sie nach Optionale Funktionen verwalten.
  2. Klicken Sie auf Funktion hinzufügen.
  3. Wählen Sie japanische Zusatzschrift aus und klicken Sie auf installieren.


Some tests which rely on precise pixel measurements may not work correctly on devices with Hi-DPI screen settings due to floating point precision errors. To run these tests correctly, make sure the device is set to 100% scaling.

To configure display scaling:

  1. Drücken Sie die Window-Taste und suchen Sie nach Anzeigeeinstellungen.
  2. Stellen Sie unter Skalieren und Layout sicher, dass das Gerät auf 100% gesetzt ist.