README: Add testing instructions

Author: A6GibKm

README.md

@@ -12,6 +12,80 @@ The repository consists of the following projects:
 - [portal](./portal/): [org.freedesktop.impl.portal.Secret](https://flatpak.github.io/xdg-desktop-portal/docs/doc-org.freedesktop.impl.portal.Secret.html) implementation
 - [server](./server/): [org.freedesktop.secrets](https://specifications.freedesktop.org/secret-service-spec/latest/) server implementation
 
+## Hacking on oo7 services
+
+### Testing oo7-daemon
+
+The daemon can be testing by simply compiling and running the binary with
+
+```sh
+cargo run --bin oo7-daemon -- --verbose --replace --login
+```
+
+Note however that if `gnome-keyring-daemon` is running, it will need to be
+killed directly before running `oo7-daemon`, as it is not running as a systemd
+service.
+
+### Testing oo7-portal
+
+The oo7-portal service can be tested using [systemd-sysext][systemd-sysext].
+Directly running the binary is possible, but without a `oo7-portal.portal` file,
+`xdg-desktop-portal` will ignore it.
+
+First build the services on its subdirectory:
+
+```sh
+cd oo7-portal
+meson setup --prefix=/usr _build
+meson compile -C _build
+DESTDIR=oo7-extension meson install -C _build
+```
+
+This will create a `oo7-extension` directory under `oo7-portal/_build`, which
+can be moved to `/run/extensions`, afterwards extensions can be reloaded via
+
+```sh
+systemd-sysext refresh --force
+```
+
+> [!WARNING]
+> In Fedora Silverblue one needs to disable SELinux via `setenforce 0` before
+> loading any system extensions.
+
+The portal can be then started with:
+```sh
+/usr/libexec/oo7-portal --replace --verbose
+```
+
+In order for `xdg-desktop-portal` to use `oo7-portal` as a server for
+`org.freedesktop.impl.portal.Secret` it needs to be configured via a
+[portals.conf][portals.conf] file at `/etc/xdg-desktop-portal/portals.conf`, see
+the `portals.conf(5)` man page.
+
+This can be achieved by creating a file at
+`~/.config/xdg-desktop-portal/gnome-portals.conf` with contents:
+
+``` toml
+[preferred]
+default=gnome;gtk;
+org.freedesktop.impl.portal.Secret=oo7-portal;gnome-keyring;
+```
+
+and then, restarting `xdg-desktop-portal` via
+
+```sh
+systemctl restart --user xdg-desktop-portal
+```
+
+If more output is required, the later can be replaced with:
+
+```sh
+/usr/libexec/xdg-desktop-portal --replace --verbose
+```
+
 ## License
 
 The project is released under the MIT license.
+
+[portals.conf]: https://flatpak.github.io/xdg-desktop-portal/docs/portals.conf.html
+[systemd-sysext]: https://www.freedesktop.org/software/systemd/man/latest/systemd-sysext.html