Add get_org_installation to AppsRequestHandler

Similarly to get_repository_installation, this fetches the installation
for the given organization.

Sample response payload copied from the API docs: https://docs.github.com/en/rest/apps/apps?apiVersion=2022-11-28#get-an-organization-installation-for-the-authenticated-app

src/api/apps.rs

@@ -97,4 +97,14 @@ impl<'octo> AppsRequestHandler<'octo> {
 
         self.crab.get(&route, None::<&()>).await
     }
+
+    /// Get an organization installation for the authenticated app.
+    pub async fn get_org_installation(
+        &self,
+        owner: impl AsRef<str>,
+    ) -> crate::Result<crate::models::Installation> {
+        let route = format!("/orgs/{owner}/installation", owner = owner.as_ref(),);
+
+        self.crab.get(&route, None::<&()>).await
+    }
 }

tests/org_installations_test.rs

@@ -0,0 +1,57 @@
+// Tests for calls to the /orgs/{org}/installation endpoint.
+mod mock_error;
+
+use mock_error::setup_error_handler;
+use octocrab::models::{Author, Installation, InstallationId};
+use octocrab::Octocrab;
+use wiremock::{
+    matchers::{method, path},
+    Mock, MockServer, ResponseTemplate,
+};
+
+async fn setup_api(template: ResponseTemplate) -> MockServer {
+    let mock_server = MockServer::start().await;
+
+    Mock::given(method("GET"))
+        .and(path("/orgs/github/installation"))
+        .respond_with(template)
+        .mount(&mock_server)
+        .await;
+    setup_error_handler(
+        &mock_server,
+        "GET on /orgs/github/installation was not received",
+    )
+    .await;
+    mock_server
+}
+
+fn setup_octocrab(uri: &str) -> Octocrab {
+    Octocrab::builder().base_uri(uri).unwrap().build().unwrap()
+}
+
+#[tokio::test]
+async fn should_return_org_installation() {
+    let org_installation_response: Installation =
+        serde_json::from_str(include_str!("resources/orgs_installation_event.json")).unwrap();
+    let template = ResponseTemplate::new(200).set_body_json(&org_installation_response);
+    let mock_server = setup_api(template).await;
+    let client = setup_octocrab(&mock_server.uri());
+
+    let result = client.apps().get_org_installation("github").await;
+
+    assert!(
+        result.is_ok(),
+        "expected successful result, got error: {:#?}",
+        result
+    );
+
+    let Installation {
+        id: installation_id,
+        account: Author { login, .. },
+        ..
+    } = result.unwrap();
+    {
+        assert_eq!(installation_id, InstallationId(1));
+        assert_eq!(login, "github");
+    }
+}

tests/resources/orgs_installation_event.json

@@ -0,0 +1,50 @@
+{
+  "id": 1,
+  "account": {
+    "login": "github",
+    "id": 1,
+    "node_id": "MDEyOk9yZ2FuaXphdGlvbjE=",
+    "avatar_url": "https://github.com/images/error/hubot_happy.gif",
+    "gravatar_id": "",
+    "url": "https://api.github.com/orgs/github",
+    "html_url": "https://github.com/github",
+    "followers_url": "https://api.github.com/users/github/followers",
+    "following_url": "https://api.github.com/users/github/following{/other_user}",
+    "gists_url": "https://api.github.com/users/github/gists{/gist_id}",
+    "starred_url": "https://api.github.com/users/github/starred{/owner}{/repo}",
+    "subscriptions_url": "https://api.github.com/users/github/subscriptions",
+    "organizations_url": "https://api.github.com/users/github/orgs",
+    "repos_url": "https://api.github.com/orgs/github/repos",
+    "events_url": "https://api.github.com/orgs/github/events",
+    "received_events_url": "https://api.github.com/users/github/received_events",
+    "type": "Organization",
+    "site_admin": false
+  },
+  "repository_selection": "all",
+  "access_tokens_url": "https://api.github.com/installations/1/access_tokens",
+  "repositories_url": "https://api.github.com/installation/repositories",
+  "html_url": "https://github.com/organizations/github/settings/installations/1",
+  "app_id": 1,
+  "target_id": 1,
+  "target_type": "Organization",
+  "permissions": {
+    "checks": "write",
+    "metadata": "read",
+    "contents": "read"
+  },
+  "events": [
+    "push",
+    "pull_request"
+  ],
+  "created_at": "2018-02-09T20:51:14Z",
+  "updated_at": "2018-02-09T20:51:14Z",
+  "single_file_name": "config.yml",
+  "has_multiple_single_files": true,
+  "single_file_paths": [
+    "config.yml",
+    ".github/issue_TEMPLATE.md"
+  ],
+  "app_slug": "github-actions",
+  "suspended_at": null,
+  "suspended_by": null
+}