From 143632adb008723315f9cf40869d31bbc984e3b1 Mon Sep 17 00:00:00 2001 From: Michael Weimann Date: Thu, 1 Sep 2022 13:49:44 +0200 Subject: [PATCH] Add 2022 code style (#23153) * Add 2022 code style * Update CONTRIBUTING/code_style --- CONTRIBUTING.md | 285 +++++++++++++++++++++++++++++- code_style.md | 455 ++++++++++++++++++++++++++++++++++++++++++++++++ 2 files changed, 737 insertions(+), 3 deletions(-) create mode 100644 code_style.md diff --git a/CONTRIBUTING.md b/CONTRIBUTING.md index e14c75df97..37391f54f5 100644 --- a/CONTRIBUTING.md +++ b/CONTRIBUTING.md @@ -1,4 +1,283 @@ -Contributing code to Element -============================ +Contributing code to Element Web +================================ -Element follows the same pattern as the [matrix-js-sdk](https://github.com/matrix-org/matrix-js-sdk/blob/develop/CONTRIBUTING.md). +Everyone is welcome to contribute code to Element Web, provided that they are +willing to license their contributions under the same license as the project +itself. We follow a simple 'inbound=outbound' model for contributions: the act +of submitting an 'inbound' contribution means that the contributor agrees to +license the code under the same terms as the project's overall 'outbound' +license - in this case, Apache Software License v2 (see +[LICENSE](LICENSE)). + +How to contribute +----------------- + +The preferred and easiest way to contribute changes to the project is to fork +it on github, and then create a pull request to ask us to pull your changes +into our repo (https://help.github.com/articles/using-pull-requests/) + +We use GitHub's pull request workflow to review the contribution, and either +ask you to make any refinements needed or merge it and make them ourselves. + +Things that should go into your PR description: + * A changelog entry in the `Notes` section (see below) + * References to any bugs fixed by the change (in GitHub's `Fixes` notation) + * Describe the why and what is changing in the PR description so it's easy for + onlookers and reviewers to onboard and context switch. This information is + also helpful when we come back to look at this in 6 months and ask "why did + we do it like that?" we have a chance of finding out. + * Why didn't it work before? Why does it work now? What use cases does it + unlock? + * If you find yourself adding information on how the code works or why you + chose to do it the way you did, make sure this information is instead + written as comments in the code itself. + * Sometimes a PR can change considerably as it is developed. In this case, + the description should be updated to reflect the most recent state of + the PR. (It can be helpful to retain the old content under a suitable + heading, for additional context.) + * Include both **before** and **after** screenshots to easily compare and discuss + what's changing. + * Include a step-by-step testing strategy so that a reviewer can check out the + code locally and easily get to the point of testing your change. + * Add comments to the diff for the reviewer that might help them to understand + why the change is necessary or how they might better understand and review it. + +We rely on information in pull request to populate the information that goes into +the changelogs our users see, both for Element Web itself and other projects on +which it is based. This is picked up from both labels on the pull request and +the `Notes:` annotation in the description. By default, the PR title will be +used for the changelog entry, but you can specify more options, as follows. + +To add a longer, more detailed description of the change for the changelog: + + +*Fix llama herding bug* + +``` +Notes: Fix a bug (https://github.com/matrix-org/notaproject/issues/123) where the 'Herd' button would not herd more than 8 Llamas if the moon was in the waxing gibbous phase +``` + +For some PRs, it's not useful to have an entry in the user-facing changelog (this is +the default for PRs labelled with `T-Task`): + +*Remove outdated comment from `Ungulates.ts`* +``` +Notes: none +``` + +Sometimes, you're fixing a bug in a downstream project, in which case you want +an entry in that project's changelog. You can do that too: + +*Fix another herding bug* +``` +Notes: Fix a bug where the `herd()` function would only work on Tuesdays +element-web notes: Fix a bug where the 'Herd' button only worked on Tuesdays +``` + +This example is for Element Web. You can specify: + * matrix-react-sdk + * element-web + * element-desktop + +If your PR introduces a breaking change, use the `Notes` section in the same +way, additionally adding the `X-Breaking-Change` label (see below). There's no need +to specify in the notes that it's a breaking change - this will be added +automatically based on the label - but remember to tell the developer how to +migrate: + +*Remove legacy class* + +``` +Notes: Remove legacy `Camelopard` class. `Giraffe` should be used instead. +``` + +Other metadata can be added using labels. + * `X-Breaking-Change`: A breaking change - adding this label will mean the change causes a *major* version bump. + * `T-Enhancement`: A new feature - adding this label will mean the change causes a *minor* version bump. + * `T-Defect`: A bug fix (in either code or docs). + * `T-Task`: No user-facing changes, eg. code comments, CI fixes, refactors or tests. Won't have a changelog entry unless you specify one. + +If you don't have permission to add labels, your PR reviewer(s) can work with you +to add them: ask in the PR description or comments. + +We use continuous integration, and all pull requests get automatically tested: +if your change breaks the build, then the PR will show that there are failed +checks, so please check back after a few minutes. + +Tests +----- +Your PR should include tests. + +For new user facing features in `matrix-js-sdk`, `matrix-react-sdk` or `element-web`, you +must include: + +1. Comprehensive unit tests written in Jest. These are located in `/test`. +2. "happy path" end-to-end tests. + These are located in `/cypress/e2e` in `matrix-react-sdk`, and + are run using `element-web`. Ideally, you would also include tests for edge + and error cases. + +Unit tests are expected even when the feature is in labs. It's good practice +to write tests alongside the code as it ensures the code is testable from +the start, and gives you a fast feedback loop while you're developing the +functionality. End-to-end tests should be added prior to the feature +leaving labs, but don't have to be present from the start (although it might +be beneficial to have some running early, so you can test things faster). + +For bugs in those repos, your change must include at least one unit test or +end-to-end test; which is best depends on what sort of test most concisely +exercises the area. + +Changes to must be accompanied by unit tests written in Jest. +These are located in `/spec/` in `matrix-js-sdk` or `/test/` in `element-web` +and `matrix-react-sdk`. + +When writing unit tests, please aim for a high level of test coverage +for new code - 80% or greater. If you cannot achieve that, please document +why it's not possible in your PR. + +Some sections of code are not sensible to add coverage for, such as those +which explicitly inhibit noisy logging for tests. Which can be hidden using +an istanbul magic comment as [documented here][1]. See example: +```javascript +/* istanbul ignore if */ +if (process.env.NODE_ENV !== "test") { + logger.error("Log line that is noisy enough in tests to want to skip"); +} +``` + +Tests validate that your change works as intended and also document +concisely what is being changed. Ideally, your new tests fail +prior to your change, and succeed once it has been applied. You may +find this simpler to achieve if you write the tests first. + +If you're spiking some code that's experimental and not being used to support +production features, exceptions can be made to requirements for tests. +Note that tests will still be required in order to ship the feature, and it's +strongly encouraged to think about tests early in the process, as adding +tests later will become progressively more difficult. + +If you're not sure how to approach writing tests for your change, ask for help +in [#element-dev](https://matrix.to/#/#element-dev:matrix.org). + +Code style +---------- +Element Web aims to target TypeScript/ES6. All new files should be written in +TypeScript and existing files should use ES6 principles where possible. + +Members should not be exported as a default export in general - it causes problems +with the architecture of the SDK (index file becomes less clear) and could +introduce naming problems (as default exports get aliased upon import). In +general, avoid using `export default`. + +The remaining code style is documented in [code_style.md](./code_style.md). +Contributors are encouraged to it and follow the principles set out there. + +Please ensure your changes match the cosmetic style of the existing project, +and ***never*** mix cosmetic and functional changes in the same commit, as it +makes it horribly hard to review otherwise. + +Attribution +----------- +Everyone who contributes anything to Matrix is welcome to be listed in the +AUTHORS.rst file for the project in question. Please feel free to include a +change to AUTHORS.rst in your pull request to list yourself and a short +description of the area(s) you've worked on. Also, we sometimes have swag to +give away to contributors - if you feel that Matrix-branded apparel is missing +from your life, please mail us your shipping address to matrix at matrix.org +and we'll try to fix it :) + +Sign off +-------- +In order to have a concrete record that your contribution is intentional +and you agree to license it under the same terms as the project's license, we've +adopted the same lightweight approach that the Linux Kernel +(https://www.kernel.org/doc/Documentation/SubmittingPatches), Docker +(https://github.com/docker/docker/blob/master/CONTRIBUTING.md), and many other +projects use: the DCO (Developer Certificate of Origin: +http://developercertificate.org/). This is a simple declaration that you wrote +the contribution or otherwise have the right to contribute it to Matrix: + +``` +Developer Certificate of Origin +Version 1.1 + +Copyright (C) 2004, 2006 The Linux Foundation and its contributors. +660 York Street, Suite 102, +San Francisco, CA 94110 USA + +Everyone is permitted to copy and distribute verbatim copies of this +license document, but changing it is not allowed. + +Developer's Certificate of Origin 1.1 + +By making a contribution to this project, I certify that: + +(a) The contribution was created in whole or in part by me and I + have the right to submit it under the open source license + indicated in the file; or + +(b) The contribution is based upon previous work that, to the best + of my knowledge, is covered under an appropriate open source + license and I have the right under that license to submit that + work with modifications, whether created in whole or in part + by me, under the same open source license (unless I am + permitted to submit under a different license), as indicated + in the file; or + +(c) The contribution was provided directly to me by some other + person who certified (a), (b) or (c) and I have not modified + it. + +(d) I understand and agree that this project and the contribution + are public and that a record of the contribution (including all + personal information I submit with it, including my sign-off) is + maintained indefinitely and may be redistributed consistent with + this project or the open source license(s) involved. +``` + +If you agree to this for your contribution, then all that's needed is to +include the line in your commit or pull request comment: + +``` +Signed-off-by: Your Name +``` + +We accept contributions under a legally identifiable name, such as your name on +government documentation or common-law names (names claimed by legitimate usage +or repute). Unfortunately, we cannot accept anonymous contributions at this +time. + +Git allows you to add this signoff automatically when using the `-s` flag to +`git commit`, which uses the name and email set in your `user.name` and +`user.email` git configs. + +If you forgot to sign off your commits before making your pull request and are +on Git 2.17+ you can mass signoff using rebase: + +``` +git rebase --signoff origin/develop +``` + +Review expectations +=================== + +See https://github.com/vector-im/element-meta/wiki/Review-process + + +Merge Strategy +============== + +The preferred method for merging pull requests is squash merging to keep the +commit history trim, but it is up to the discretion of the team member merging +the change. We do not support rebase merges due to `allchange` being unable to +handle them. When merging make sure to leave the default commit title, or +at least leave the PR number at the end in brackets like by default. +When stacking pull requests, you may wish to do the following: + +1. Branch from develop to your branch (branch1), push commits onto it and open a pull request +2. Branch from your base branch (branch1) to your work branch (branch2), push commits and open a pull request configuring the base to be branch1, saying in the description that it is based on your other PR. +3. Merge the first PR using a merge commit otherwise your stacked PR will need a rebase. Github will automatically adjust the base branch of your other PR to be develop. + + +[1]: https://github.com/gotwarlost/istanbul/blob/master/ignoring-code-for-coverage.md diff --git a/code_style.md b/code_style.md new file mode 100644 index 0000000000..79840d4eeb --- /dev/null +++ b/code_style.md @@ -0,0 +1,455 @@ +# Element Web/Desktop code style guide + +This code style applies to projects which the element-web team directly maintains or is reasonably +adjacent to. As of writing, these are: + +* element-desktop +* element-web +* matrix-react-sdk +* matrix-js-sdk + +Other projects might extend this code style for increased strictness. For example, matrix-events-sdk +has stricter code organization to reduce the maintenance burden. These projects will declare their code +style within their own repos. + +Note that some requirements will be layer-specific. Where the requirements don't make sense for the +project, they are used to the best of their ability, used in spirit, or ignored if not applicable, +in that order. + +## Guiding principles + +1. We want the lint rules to feel natural for most team members. No one should have to think too much + about the linter. +2. We want to stay relatively close to [industry standards](https://google.github.io/styleguide/tsguide.html) + to make onboarding easier. +3. We describe what good code looks like rather than point out bad examples. We do this to avoid + excessively punishing people for writing code which fails the linter. +4. When something isn't covered by the style guide, we come up with a reasonable rule rather than + claim that it "passes the linter". We update the style guide and linter accordingly. +5. While we aim to improve readability, understanding, and other aspects of the code, we deliberately + do not let solely our personal preferences drive decisions. +6. We aim to have an understandable guide. + +## Coding practices + +1. Lint rules enforce decisions made by this guide. The lint rules and this guide are kept in + perfect sync. +2. Commit messages are descriptive for the changes. When the project supports squash merging, + only the squashed commit needs to have a descriptive message. +3. When there is disagreement with a code style approved by the linter, a PR is opened against + the lint rules rather than making exceptions on the responsible code PR. +4. Rules which are intentionally broken (via eslint-ignore, @ts-ignore, etc) have a comment + included in the immediate vicinity for why. Determination of whether this is valid applies at + code review time. +5. When editing a file, nearby code is updated to meet the modern standards. "Nearby" is subjective, + but should be whatever is reasonable at review time. Such an example might be to update the + class's code style, but not the file's. + 1. These changes should be minor enough to include in the same commit without affecting a code + reviewer's job. + +## All code + +Unless otherwise specified, the following applies to all code: + +1. 120 character limit per line. Match existing code in the file if it is using a lower guide. +2. A tab/indentation is 4 spaces. +3. Newlines are Unix. +4. A file has a single empty line at the end. +5. Lines are trimmed of all excess whitespace, including blank lines. +6. Long lines are broken up for readability. + +## TypeScript / JavaScript {#typescript-javascript} + +1. Write TypeScript. Turn JavaScript into TypeScript when working in the area. +2. Use named exports. +3. Break long lines to appear as follows: + + ```typescript + // Function arguments + function doThing( + arg1: string, + arg2: string, + arg3: string, + ): boolean { + return !!arg1 + && !!arg2 + && !!arg3; + } + + // Calling a function + doThing( + "String 1", + "String 2", + "String 3", + ); + + // Reduce line verbosity when possible/reasonable + doThing( + "String1", "String 2", + "A much longer string 3", + ); + + // Chaining function calls + something.doThing() + .doOtherThing() + .doMore() + .somethingElse(it => + useIt(it) + ); + ``` +4. Use semicolons for block/line termination. + 1. Except when defining interfaces, classes, and non-arrow functions specifically. +5. When a statement's body is a single line, it may be written without curly braces, so long as the body is placed on + the same line as the statement. + + ```typescript + if (x) doThing(); + ``` +6. Blocks for `if`, `for`, `switch` and so on must have a space surrounding the condition, but not + within the condition. + + ```typescript + if (x) { + doThing(); + } + ``` +7. Mixing of logical operands requires brackets to explicitly define boolean logic. + + ```typescript + if ((a > b && b > c) || (d < e)) return true; + ``` +8. Ternaries use the same rules as `if` statements, plus the following: + + ```typescript + // Single line is acceptable + const val = a > b ? doThing() : doOtherThing(); + + // Multiline is also okay + const val = a > b + ? doThing() + : doOtherThing(); + + // Use brackets when using multiple conditions. + // Maximum 3 conditions, prefer 2 or less. + const val = (a > b && b > c) ? doThing() : doOtherThing(); + ``` +9. lowerCamelCase is used for function and variable naming. +10. UpperCamelCase is used for general naming. +11. Interface names should not be marked with an uppercase `I`. +12. One variable declaration per line. +13. If a variable is not receiving a value on declaration, its type must be defined. + + ```typescript + let errorMessage: Optional; + ``` +14. Objects, arrays, enums and so on must have each line terminated with a comma: + + ```typescript + const obj = { + prop: 1, + else: 2, + }; + + const arr = [ + "one", + "two", + ]; + + enum Thing { + Foo, + Bar, + } + + doThing( + "arg1", + "arg2", + ); + ``` +15. Objects can use shorthand declarations, including mixing of types. + + ```typescript + { + room, + prop: this.prop, + } + // ... or ... + { room, prop: this.prop } + ``` +16. Object keys should always be non-strings when possible. + + ```typescript + { + property: "value", + "m.unavoidable": true, + [EventType.RoomMessage]: true, + } + ``` +17. Explicitly cast to a boolean. + + ```typescript + !!stringVar || Boolean(stringVar) + ``` +18. Use `switch` statements when checking against more than a few enum-like values. +19. Use `const` for constants, `let` for mutability. +20. Describe types exhaustively (ensure noImplictAny would pass). + 1. Notable exceptions are arrow functions used as parameters, when a void return type is + obvious, and when declaring and assigning a variable in the same line. +21. Declare member visibility (public/private/protected). +22. Private members are private and not prefixed unless required for naming conflicts. + 1. Convention is to use an underscore or the word "internal" to denote conflicted member names. + 2. "Conflicted" typically refers to a getter which wants the same name as the underlying variable. +23. Prefer readonly members over getters backed by a variable, unless an internal setter is required. +24. Prefer Interfaces for object definitions, and types for parameter-value-only declarations. + 1. Note that an explicit type is optional if not expected to be used outside of the function call, + unlike in this example: + + ```typescript + interface MyObject { + hasString: boolean; + } + + type Options = MyObject | string; + + function doThing(arg: Options) { + // ... + } + ``` +25. Variables/properties which are `public static` should also be `readonly` when possible. +26. Interface and type properties are terminated with semicolons, not commas. +27. Prefer arrow formatting when declaring functions for interfaces/types: + + ```typescript + interface Test { + myCallback: (arg: string) => Promise; + } + ``` +28. Prefer a type definition over an inline type. For example, define an interface. +29. Always prefer to add types or declare a type over the use of `any`. Prefer inferred types + when they are not `any`. + 1. When using `any`, a comment explaining why must be present. +30. `import` should be used instead of `require`, as `require` does not have types. +31. Export only what can be reused. +32. Prefer a type like `Optional` (`type Optional = T | null | undefined`) instead + of truly optional parameters. + 1. A notable exception is when the likelihood of a bug is minimal, such as when a function + takes an argument that is more often not required than required. An example where the + `?` operator is inappropriate is when taking a room ID: typically the caller should + supply the room ID if it knows it, otherwise deliberately acknowledge that it doesn't + have one with `null`. + + ```typescript + function doThingWithRoom( + thing: string, + room: Optional, // require the caller to specify + ) { + // ... + } + ``` +33. There should be approximately one interface, class, or enum per file unless the file is named + "types.ts", "global.d.ts", or ends with "-types.ts". + 1. The file name should match the interface, class, or enum name. +34. Bulk functions can be declared in a single file, though named as "foo-utils.ts" or "utils/foo.ts". +35. Imports are grouped by external module imports first, then by internal imports. +36. File ordering is not strict, but should generally follow this sequence: + 1. Licence header + 2. Imports + 3. Constants + 4. Enums + 5. Interfaces + 6. Functions + 7. Classes + 1. Public/protected/private static properties + 2. Public/protected/private properties + 3. Constructors + 4. Public/protected/private getters & setters + 5. Protected and abstract functions + 6. Public/private functions + 7. Public/protected/private static functions +37. Variable names should be noticeably unique from their types. For example, "str: string" instead + of "string: string". +38. Use double quotes to enclose strings. You may use single quotes if the string contains double quotes. + + ```typescript + const example1 = "simple string"; + const example2 = 'string containing "double quotes"'; + ``` +39. Prefer async-await to promise-chaining + + ```typescript + async function () { + const result = await anotherAsyncFunction(); + // ... + } + ``` + +## React + +Inheriting all the rules of TypeScript, the following additionally apply: + +1. Types for lifecycle functions are not required (render, componentDidMount, and so on). +2. Class components must always have a `Props` interface declared immediately above them. It can be + empty if the component accepts no props. +3. Class components should have an `State` interface declared immediately above them, but after `Props`. +4. Props and State should not be exported. Use `React.ComponentProps` + instead. +5. One component per file, except when a component is a utility component specifically for the "primary" + component. The utility component should not be exported. +6. Exported constants, enums, interfaces, functions, etc must be separate from files containing components + or stores. +7. Stores should use a singleton pattern with a static instance property: + + ```typescript + class FooStore { + public static readonly instance = new FooStore(); + + // or if the instance can't be created eagerly: + private static _instance: FooStore; + public static get instance(): FooStore { + if (!FooStore._instance) { + FooStore._instance = new FooStore(); + } + return FooStore._instance; + } + } + ``` +8. Stores must support using an alternative MatrixClient and dispatcher instance. +9. Utilities which require JSX must be split out from utilities which do not. This is to prevent import + cycles during runtime where components accidentally include more of the app than they intended. +10. Interdependence between stores should be kept to a minimum. Break functions and constants out to utilities + if at all possible. +11. A component should only use CSS class names in line with the component name. + 1. When knowingly using a class name from another component, document it. +12. Break components over multiple lines like so: + + ```typescript + function render() { + return ; + + // or + + return ( + + ); + + // or if children are needed (infer parens usage) + + return { _t("Short string here") }; + + + + return + { _t("Longer string here") } + ; + } + ``` +13. Curly braces within JSX should be padded with a space, however properties on those components should not. + See above code example. +14. Functions used as properties should either be defined on the class or stored in a variable. They should not + be inline unless mocking/short-circuiting the value. +15. Prefer hooks (functional components) over class components. Be consistent with the existing area if unsure + which should be used. + 1. Unless the component is considered a "structure", in which case use classes. +16. Write more views than structures. Structures are chunks of functionality like MatrixChat while views are + isolated components. +17. Components should serve a single, or near-single, purpose. +18. Prefer to derive information from component properties rather than establish state. +19. Do not use `React.Component::forceUpdate`. + +## Stylesheets (\*.pcss = PostCSS + Plugins) + +Note: We use PostCSS + some plugins to process our styles. It looks like SCSS, but actually it is not. + +1. Class names must be prefixed with "mx_". +2. Class names should denote the component which defines them, followed by any context: + 1. mx_MyFoo + 2. mx_MyFoo_avatar + 3. mx_MyFoo_avatar--user +3. Use the `$font` and `$spacing` variables instead of manual values. +4. Keep indentation/nesting to a minimum. Maximum suggested nesting is 5 layers. +5. Use the whole class name instead of shortcuts: + + ```scss + .mx_MyFoo { + & .mx_MyFoo_avatar { // instead of &_avatar + // ... + } + } + ``` +6. Break multiple selectors over multiple lines this way: + + ```scss + .mx_MyFoo, + .mx_MyBar, + .mx_MyFooBar { + // ... + } + ``` +7. Non-shared variables should use $lowerCamelCase. Shared variables use $dashed-naming. +8. Overrides to Z indexes, adjustments of dimensions/padding with pixels, and so on should all be + documented for what the values mean: + + ```scss + .mx_MyFoo { + width: calc(100% - 12px); // 12px for read receipts + top: -2px; // visually centred vertically + z-index: 10; // above user avatar, but below dialogs + } + ``` +9. Avoid the use of `!important`. If necessary, add a comment. + +## Tests + +1. Tests must be written in TypeScript. +2. Jest mocks are declared below imports, but above everything else. +3. Use the following convention template: + + ```typescript + // Describe the class, component, or file name. + describe("FooComponent", () => { + // all test inspecific variables go here + + beforeEach(() => { + // exclude if not used. + }); + + afterEach(() => { + // exclude if not used. + }); + + // Use "it should..." terminology + it("should call the correct API", async () => { + // test-specific variables go here + + // function calls/state changes go here + + // expectations go here + }); + }); + + // If the file being tested is a utility class: + describe("foo-utils", () => { + describe("firstUtilFunction", () => { + it("should...", async () => { + // ... + }); + }); + + describe("secondUtilFunction", () => { + it("should...", async () => { + // ... + }); + }); + }); + ```