Generate help dynamically

Before, it was a static string and it was easy to forget to add new commands to it.

Author: Kobzol

src/bors/handlers/help.rs

@@ -1,36 +1,81 @@
-use std::sync::Arc;
-
+use crate::bors::command::{Approver, BorsCommand};
 use crate::bors::Comment;
 use crate::bors::RepositoryState;
 use crate::github::PullRequest;
-
-const HELP_MESSAGE: &str = r#"
-- try: Execute the `try` CI workflow on this PR (without approving it for a merge).
-- try cancel: Stop try builds on current PR.
-- ping: pong
-- help: Print this help message
-"#;
+use std::sync::Arc;
 
 pub(super) async fn command_help(
     repo: Arc<RepositoryState>,
     pr: &PullRequest,
 ) -> anyhow::Result<()> {
+    let help = [
+        BorsCommand::Approve(Approver::Myself),
+        BorsCommand::Approve(Approver::Specified("".to_string())),
+        BorsCommand::Unapprove,
+        BorsCommand::Try {
+            parent: None,
+            jobs: vec![],
+        },
+        BorsCommand::TryCancel,
+        BorsCommand::Ping,
+        BorsCommand::Help,
+    ]
+    .into_iter()
+    .map(|help| format!("- {}", get_command_help(help)))
+    .collect::<Vec<_>>()
+    .join("\n");
+
     repo.client
-        .post_comment(pr.number, Comment::new(HELP_MESSAGE.to_string()))
+        .post_comment(pr.number, Comment::new(help))
         .await?;
     Ok(())
 }
 
+fn get_command_help(command: BorsCommand) -> String {
+    // !!! When modifying this match, also update the command list above (in [`command_help`]) !!!
+    let help = match command {
+        BorsCommand::Approve(Approver::Myself) => {
+            "`r+`: Approve this PR"
+        }
+        BorsCommand::Approve(Approver::Specified(_)) => {
+            "`r=<user>`: Approve this PR on behalf of `<user>`"
+        }
+        BorsCommand::Unapprove => {
+            "`r-`: Unapprove this PR"
+        }
+        BorsCommand::Help => {
+            "`help`: Print this help message"
+        }
+        BorsCommand::Ping => {
+            "`ping`: Check if the bot is alive"
+        }
+        BorsCommand::Try { .. } => {
+            "`try [parent=<parent>] [jobs=<jobs>]`: Start a try build. Optionally, you can specify a `<parent>` SHA or a list of `<jobs>` to run"
+        }
+        BorsCommand::TryCancel => {
+            "`try cancel`: Cancel a running try build"
+        }
+    };
+    help.to_string()
+}
+
 #[cfg(test)]
 mod tests {
-    use crate::bors::handlers::help::HELP_MESSAGE;
     use crate::tests::mocks::run_test;
 
     #[sqlx::test]
     async fn help_command(pool: sqlx::PgPool) {
         run_test(pool, |mut tester| async {
             tester.post_comment("@bors help").await?;
-            assert_eq!(tester.get_comment().await?, HELP_MESSAGE);
+            insta::assert_snapshot!(tester.get_comment().await?, @r"
+            - `r+`: Approve this PR
+            - `r=<user>`: Approve this PR on behalf of `<user>`
+            - `r-`: Unapprove this PR
+            - `try [parent=<parent>] [jobs=<jobs>]`: Start a try build. Optionally, you can specify a `<parent>` SHA or a list of `<jobs>` to run
+            - `try cancel`: Cancel a running try build
+            - `ping`: Check if the bot is alive
+            - `help`: Print this help message
+            ");
             Ok(tester)
         })
         .await;