One intentional omission from this list is `@angular/compiler`, which is currently considered a low level api and is subject to internal changes. These changes will not affect any applications or libraries using the higher-level apis (the command line interface or JIT compilation via `@angular/platform-browser-dynamic`). Only very specific use-cases require direct access to the compiler API (mostly tooling integration for IDEs, linters, etc). If you are working on this kind of integration, please reach out to us first.
Other projects developed by the Angular team like angular-cli, Angular Material, will be covered by these or similar guarantees in the future as they mature.
Within the supported packages, we provide guarantees for:
- symbols exported via the main entry point (e.g. `@angular/core`) and testing entry point (e.g. `@angular/core/testing`). This applies to both runtime/JavaScript values and TypeScript types.
- symbols exported via global namespace `ng` (e.g. `ng.core`)
- bundles located in the `bundles/` directory of our npm packages (e.g. `@angular/core/bundles/core.umd.js`)
We explicitly don't consider the following to be our public API surface:
- any class members or symbols marked as `private`, or prefixed with underscore (`_`), [barred latin o](https://en.wikipedia.org/wiki/%C6%9F) (`ɵ`), and double barred latin o (`ɵɵ`).
- extending any of our classes unless the support for this is specifically documented in the API docs
- the contents and API surface of the code generated by Angular's compiler (with one notable exception: the existence and name of `NgModuleFactory` instances exported from generated code is guaranteed)
Our peer dependencies (such as TypeScript, Zone.js, or RxJS) are not considered part of our API surface, but they are included in our SemVer policies. We might update the required version of any of these dependencies in minor releases if the update doesn't cause breaking changes for Angular applications. Peer dependency updates that result in non-trivial breaking changes must be deferred to major Angular releases.
Angular tracks the status of the public API in a *golden file*, maintained with a tool called the *public API guard*.
If you modify any part of a public API in one of the supported public packages, the PR can fail a test in CI with an error message that instructs you to accept the golden file.
The public API guard provides a Bazel target that updates the current status of a given package. If you add to or modify the public API in any way, you must use [yarn](https://yarnpkg.com/) to execute the Bazel target in your terminal shell of choice (a recent version of `bash` is recommended).
yarn bazel run //tools/public_api_guard:<modified_package>_api.accept
```
Using yarn ensures that you are running the correct version of Bazel.
(Read more about building Angular with Bazel [here](./BAZEL.md).)
Here is an example of a Circle CI test failure that resulted from adding a new allowed type to a public property in `forms.d.ts`. Error messages from the API guard use [`git-diff` formatting](https://git-scm.com/docs/git-diff#_combined_diff_format).
```
FAIL: //tools/public_api_guard:forms_api (see /home/circleci/.cache/bazel/_bazel_circleci/9ce5c2144ecf75d11717c0aa41e45a8d/execroot/angular/bazel-out/k8-fastbuild/testlogs/tools/public_api_guard/forms_api/test_attempts/attempt_1.log)
FAIL: //tools/public_api_guard:forms_api (see /home/circleci/.cache/bazel/_bazel_circleci/9ce5c2144ecf75d11717c0aa41e45a8d/execroot/angular/bazel-out/k8-fastbuild/testlogs/tools/public_api_guard/forms_api/test.log)
