| # `fuchsia.element` CTS test |
| |
| This is a compatibility test for `fuchsia.element` FIDL APIs. |
| |
| ## Motivation |
| |
| Fuchsia provides tools and APIs to create product experiences that combine |
| software from the platform (e.g. `session_manager`), product (the [session |
| component][glossary.session-component]), and user-visible components. |
| Interoperability between components is a challenge because they may implement |
| the framework’s contracts differently or rely on undocumented behaviors. |
| |
| The Fuchsia [Compatibility Test Suite][doc-cts-rfc] (CTS) is a collection of |
| tests that ensure a Fuchsia product build is backwards-compatible with software |
| written against previous versions of the platform. |
| |
| Session compatibility tests are a subset of the CTS that exercise contracts |
| between: |
| |
| 1. **Platform and session**: ensuring platform changes do not break existing |
| sessions, including changes to platform-provided session components (e.g. |
| input pipeline, `element_manager`) |
| 2. **Session and user-visible components**: ensuring sessions are compatible |
| with common types of user-visible components — for example, that a Flutter |
| app is launched and presented similarly on different products. |
| |
| ## Component Topology |
| |
| Session CTS tests are CFv2 components that launch a Session Framework and the |
| session under test in an isolated environment. |
| |
| The tests start a reference session that is composed from platform-provided |
| components. It is intended for testing the Session CTS itself (all tests should |
| pass with the reference session), and for integration testing the |
| platform-provided components. |
| |
|  |
| |
| ## Reference session |
| |
| Tests that exercise launching elements may use a reference element provided by |
| the CTS. |
| |
| The test suite ships with a reference session implementation that passes all |
| tests. It is a minimal session that contains just enough to exercise the tests, |
| and is not intended to be a fully-fledged example of a product. |
| |
| The reference session is not tailored specifically for the test environment. |
| Neither the tests nor the reference session know about each other’s existence, |
| as to avoid coupling tests to a particular session implementation. |
| |
| The reference session reuses platform-provided components as much as possible. |
| This encourages code reuse between products and frees developers from worrying |
| about implementing boilerplate functionality (e.g. launching element |
| components). This code needs to be packaged as a component, not a library, |
| because the CTS may only depend on SDK atoms. |
| |
| ## Tests |
| |
| ### `element_manager_test`: Proposing an element is successful |
| |
| The simplest possible test for the |
| [fuchsia.element.Manager][source-element-manager-fidl] protocol proposes an |
| element and asserts that the result was successful. |
| |
| ## Example usage |
| |
| ``` |
| $ fx set core.x64 --with-base "//sdk/ctf" |
| $ fx test fuchsia-element-tests -o |
| ``` |
| |
| [doc-cts-rfc]: /docs/contribute/governance/rfcs/0015_cts.md |
| [doc-event-capabilities]: /docs/concepts/components/v2/capabilities/event.md |
| [glossary.session-component]: /docs/glossary#session-component |
| [source-element-management]: https://cs.opensource.google/fuchsia/fuchsia/+/main:src/session/lib/element_management |
| [source-element-manager-fidl]: https://cs.opensource.google/fuchsia/fuchsia/+/main:sdk/fidl/fuchsia.element/element_manager.fidl |
| [source-element-manager]: https://cs.opensource.google/fuchsia/fuchsia/+/main:src/session/bin/element_manager |
