Initial core documentation

.vuepress/config.js

@@ -70,6 +70,15 @@ module.exports = {
           "module-development/documentation.md",
         ],
       },
+      {
+        title: "Core Development",
+        collapsable: true,
+        children: [
+          "core-development/introduction.md",
+          "core-development/testing.md",
+          "core-development/debugging.md",
+        ],
+      },
       {
         title: "About",
         collapsable: true,

core-development/debugging.md

@@ -0,0 +1,47 @@
+---
+title: Debugging
+---
+
+# Core Development Documentation: Debugging
+
+Tips and tricks for debugging MagicMirror²,
+
+## Breakpoints
+
+Node.js has support for [built-in breakpoints](https://nodejs.org/api/debugger.html), or [VSCode](https://code.visualstudio.com/) allows for
+visual breakpoints and inspecting of objects.
+
+## Date
+
+It can be very useful to set the current date to debug calendar issues. In order to do this, override `Date.now` with a lambda in *config/config.js*:
+
+```js
+Date.now = () => new Date('2023-12-31T14:05:32');
+```
+
+This will cause every request for the current time to return the specified time, at least for the core and built-in modules.
+
+**NOTE:** Some modules may use `new Date()` to get the current date/time, though this is not recommended. If this is the case,
+the external module will not work correctly for date debugging.
+
+## Timezone
+
+The `TZ` environment variable can be used to specify a valid [canonical timezone name](https://en.wikipedia.org/wiki/List_of_tz_database_time_zones)
+from the [tz database](https://en.wikipedia.org/wiki/Tz_database).
+
+Several tests do this, such as this example in *tests/electron/helpers/global-setup.js*:
+
+```js
+process.env.TZ = "GMT";
+```
+
+The *package.json* could also be modified to force a timezone for a given script, such as `start:dev`:
+
+```json
+"start:dev": "TZ=Europe/Madrid ./node_modules/.bin/electron js/electron.js dev"
+```
+
+Or when running from the command line (Linux example):
+```sh
+TZ=Europe/Madrid npm run start:dev
+```

core-development/introduction.md

@@ -0,0 +1,39 @@
+---
+title: Introduction
+---
+
+# Core Development Documentation
+
+This documentation describes core MagicMirror² development.
+
+## General
+
+MagicMirror² is a community-driven development effort, and [contributions](../about/contributing.md) are
+welcome!
+
+In general, new features and bug fixes should be tracked against an [issue in the MagicMirror repo](https://github.com/MichMich/MagicMirror/issues).
+It is always a good idea to search existing issues to see if a problem you're experiencing has already been reported,
+or if someone has already suggested a feature you'd like to propose. Creating or finding an issue also starts the
+discussion and helps build consensus around your proposed fix or feature.
+
+The MagicMirror² core is [developed on GitHub](https://github.com/MichMich/MagicMirror/) out of the
+*develop* branch. To begin developing MagicMirror² core, please fork the GitHub project and
+create a new branch based off of the *develop* branch.
+
+When your development is ready for review and testing, create a new *Pull Request* targeting the *develop* branch.
+The development team and other contributors will be able to review your changes and provide feedback, and
+the test system will run automated tests against your changes. Make sure to mention the issue(s) that your Pull
+Request solves.
+
+## Development Environment
+
+Although Node.js applications are typically platform-independent, many of the scripts created for MagicMirror² are
+Linux-based. While Windows/Mac development is possible, you may run into issues. (Improvements here are welcome!)
+
+You will need to have [Node.js installed](https://nodejs.org/en/download). When doing Linux development, on newer
+distributions Node.js is available from package managers.
+
+Many Node.js or experienced Javascript developers have an environment that works for them. New developers
+to Node.js / Electron can download [VSCode for free](https://code.visualstudio.com/download) and use many extensions available for debugging and developing Javascript.
+
+Also checkout [Building Node.js Apps with VSCode](https://code.visualstudio.com/docs/nodejs/nodejs-tutorial).

core-development/testing.md

@@ -0,0 +1,30 @@
+---
+title: Testing
+---
+
+# Core Development Documentation: Testing
+
+Unit tests are important to ensure the quality of the project as changes occur.
+
+All tests are located in the [*tests* top-level directory](https://github.com/MichMich/MagicMirror/tree/master/tests).
+
+## Hierarchy of Tests
+
+Below the *tests* directory are other directories that organize the tests:
+
+* *configs* - Configuration files for tests.
+* *e2e* - End-to-end tests that start and run MagicMirror² in various configurations.
+* *electron* - Electron application tests.
+* *mocks* - Mock-up data for tests.
+* *unit* - Unit tests for utilities and smaller portions of MagicMirror².
+* *utils* - Testing utilities.
+
+## Writing a Test
+
+Almost all pull requests must have test coverage of changes. Usually, it is easier to find an existing test and
+extend it to test your new functionality.
+
+For example, if you were writing a test for a fix in the Calendar module, you might locate *tests/e2e/modules/calendar_spec.js*
+and add an additional test there.
+
+If you have questions about how to write a test, you can also ask in the [MagicMirror forums](https://forum.magicmirror.builders/).

module-development/introduction.md

@@ -21,6 +21,8 @@ information in your README file.**
 - What external API's it depends upon, including web links to those
 - Whether the API/request require a key and the user limitations of those. (Is
   it free?)
+- **Do not use `new Date()` for the current timestamp, instead prefer `Date.now()`
+  as it can be more [easily overridden for debugging](..\core-development\debugging.md#Date)**.
 
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