src/hello_world/README.md

# Hello World Example

The Hello, World sample introduces a Fuchsia component that prints "Hello, world"
messages to the system log.
The `BUILD.gn` file contains rules that demonstrate building a single binar
with shared and static libraries as dependencies.

## Source layout

- `hello.cc`: Main entrypoint for the component binary
- `hello_shared`: Shared library exposing functions to retrieve a greeting
- `hello_static`: Static library exposing functions to retrieve a greeting

## Before you begin

1.  Start an emulator instance:

    ```
    $ ./third_party/fuchsia-sdk/tools/x64/ffx product-bundle get workstation_eng.qemu-x64
    $ ./third_party/fuchsia-sdk/tools/x64/ffx emu start workstation_eng.qemu-x64
    ```

1.  Start a local package repository instance:

    ```
    $ ./third_party/fuchsia-sdk/tools/x64/fserve --image workstation_eng.qemu-x64-release
    ```

## Build the sample

1.  Run the build script to compile and package the sample:

    ```
    $ ./scripts/build.sh
    ```

1.  Publish the FAR packages to your local package repository:

    ```
    $ ./third_party/fuchsia-sdk/tools/x64/fpublish out/x64/hello_world.far
    $ ./third_party/fuchsia-sdk/tools/x64/fpublish out/x64/hello_world_test.far
    ```

## Run the sample

1.  Launch the sample component using `ffx component run`. This resolves the
    component from the package repository and starts it:

    ```
    $ ./third_party/fuchsia-sdk/tools/x64/ffx component run fuchsia-pkg://fuchsia.com/hello_world#meta/hello_world.cm
    ```

1.  View the greeting messages in the system log using `ffx log`:

    ```
    $ ./third_party/fuchsia-sdk/tools/x64/ffx log --filter hello_world
    ...
    [hello_world][I] pthreads: hello
    [hello_world][I] Hello, world
    [hello_world][I] cppthreads: hello
    ```

## Run the unit tests

1.  Execute the unit test suite using `ffx test run`. This resolves the
    component from the package repository and executes the tests:

    ```
    $ ./third_party/fuchsia-sdk/tools/x64/ffx test run fuchsia-pkg://fuchsia.com/hello_world_test#meta/hello_world_test.cm
    ```

1.  Verify that the test cases pass:

    ```
    Running test 'fuchsia-pkg://fuchsia.com/hello_world_test#meta/hello_world_test.cm'
    [RUNNING]	HelloWorldTest.True
    [stdout - HelloWorldTest.True]
    Running main() from ../../third_party/googletest/src/googletest/src/gtest_main.cc
    [PASSED]	HelloWorldTest.True

    1 out of 1 tests passed...
    fuchsia-pkg://fuchsia.com/hello_world_test#meta/hello_world_test.cm completed with result: PASSED
    ```