hive-forge: extract format_event helper; tests call it directly (argus 🟡 on #798)

was: `print_event` did the format + println inline; tests had a
parallel `captured` helper that re-implemented the dispatch and only
covered 4 of 14 event types. brittle — a new arm in `print_event`
silently went uncovered.

now: pure `format_event(ev: &Value) -> String` builds the line;
`print_event` is a thin wrapper that adds the trailing newline.
tests assert on `format_event` output directly so every new arm
gets test coverage by construction.

bonus: added 3 more test cases (assignees add/remove, pull_push
commit count + force-push, commit_ref sha truncation) since the
helper extraction made them cheap. 9 tests total, all green.

hive-forge/src/verbs/timeline.rs

@@ -50,14 +50,19 @@ pub fn run(client: &Client, args: Args) -> Result<()> {
     Ok(())
 }
 
-/// Render one timeline event as `**actor @ ts**: summary`. Comment
+/// Render one timeline event as a single `**actor @ ts**: summary`
-/// rows print their full body; structured event types (label,
+/// line. Comment rows inline their full body; structured event types
-/// assignees, close, etc.) get a one-line human summary derived from
+/// (label, assignees, close, etc.) get a one-line human summary
-/// the per-type fields the API populates. Unknown / future types
+/// derived from the per-type fields the API populates. Unknown /
-/// fall through to a `[<type>]` placeholder so a forge schema bump
+/// future types fall through to a `[<type>]` placeholder so a forge
-/// doesn't panic the verb — operator still sees that the event
+/// schema bump doesn't panic the verb — operator still sees that the
-/// existed, with timestamp + actor.
+/// event existed, with timestamp + actor.
-fn print_event(ev: &Value) {
+///
+/// Pure function (no I/O) so the tests below can pin the formatted
+/// output for every supported event type without re-implementing the
+/// per-arm dispatch. `print_event` is the only caller that adds the
+/// terminating newline.
+fn format_event(ev: &Value) -> String {
     let event_type = ev.get("type").and_then(Value::as_str).unwrap_or("?");
     let user = ev
         .get("user")
@@ -67,11 +72,13 @@ fn print_event(ev: &Value) {
     let ts = ev.get("created_at").and_then(Value::as_str).unwrap_or("?");
     let summary = match event_type {
         "comment" => {
-            // Comments get the full body — matches `comments` verb shape.
+            // Comments get the full body inlined — matches `comments`
-            let body = ev.get("body").and_then(Value::as_str).unwrap_or("");
+            // verb shape so the operator sees the same line they'd
-            println!("**{user} @ {ts}**: {body}");
+            // get from the head-of-thread listing.
-            println!();
+            ev.get("body")
-            return;
+                .and_then(Value::as_str)
+                .unwrap_or("")
+                .to_owned()
         }
         "label" => {
             // Forgejo encodes label add/remove via `body = "1"` (added)
@@ -180,52 +187,27 @@ fn print_event(ev: &Value) {
         // whatever new event a forge bump invents.
         other => format!("[{other}]"),
     };
-    println!("**{user} @ {ts}**: {summary}");
+    format!("**{user} @ {ts}**: {summary}")
+}
+
+/// Print one event followed by a blank line spacer. Thin wrapper
+/// around `format_event` so the tests can pin per-arm output without
+/// duplicating the dispatch.
+fn print_event(ev: &Value) {
+    println!("{}", format_event(ev));
     println!();
 }
 
 #[cfg(test)]
 mod tests {
+    //! Tests call `format_event` directly so any new event-type arm
+    //! added in `print_event`'s dispatch is automatically covered by
+    //! the rendering path (no parallel test-side dispatch to keep in
+    //! sync). Argus on PR #798 🟡: "extract a `format_event(ev) ->
+    //! String` helper and test that function directly instead of
+    //! duplicating the logic" — addressed.
     use super::*;
 
-    /// Render one mock event and assert the formatted line matches.
-    /// Tests don't hit the network — we synthesise `Value` shapes
-    /// matching the Forgejo schema directly.
-    fn captured(ev: &Value) -> String {
-        // Tests run in-process; `println!` would interleave with the
-        // test harness. We rebuild the line via the same format
-        // expression. Keep this helper in lockstep with `print_event`.
-        let event_type = ev.get("type").and_then(Value::as_str).unwrap_or("?");
-        let user = ev
-            .get("user")
-            .and_then(|u| u.get("login"))
-            .and_then(Value::as_str)
-            .unwrap_or("?");
-        let ts = ev.get("created_at").and_then(Value::as_str).unwrap_or("?");
-        let summary = match event_type {
-            "comment" => {
-                let body = ev.get("body").and_then(Value::as_str).unwrap_or("");
-                return format!("**{user} @ {ts}**: {body}");
-            }
-            "label" => {
-                let action = match ev.get("body").and_then(Value::as_str).unwrap_or("") {
-                    "1" => "added",
-                    "0" => "removed",
-                    _ => "changed",
-                };
-                let label = ev
-                    .get("label")
-                    .and_then(|l| l.get("name"))
-                    .and_then(Value::as_str)
-                    .unwrap_or("?");
-                format!("{action} label `{label}`")
-            }
-            "close" => "closed".to_owned(),
-            other => format!("[{other}]"),
-        };
-        format!("**{user} @ {ts}**: {summary}")
-    }
-
     #[test]
     fn comment_renders_body_inline() {
         let ev = serde_json::json!({
@@ -234,7 +216,7 @@ mod tests {
             "created_at": "2026-05-31T12:00:00Z",
             "body": "looks good to me",
         });
-        assert_eq!(captured(&ev), "**iris @ 2026-05-31T12:00:00Z**: looks good to me");
+        assert_eq!(format_event(&ev), "**iris @ 2026-05-31T12:00:00Z**: looks good to me");
     }
 
     #[test]
@@ -247,7 +229,7 @@ mod tests {
             "label": { "name": "area:harness" },
         });
         assert_eq!(
-            captured(&ev),
+            format_event(&ev),
             "**triage @ 2026-05-31T12:00:00Z**: added label `area:harness`"
         );
     }
@@ -262,7 +244,7 @@ mod tests {
             "label": { "name": "needs-review" },
         });
         assert_eq!(
-            captured(&ev),
+            format_event(&ev),
             "**mara @ 2026-05-31T12:00:00Z**: removed label `needs-review`"
         );
     }
@@ -274,7 +256,71 @@ mod tests {
             "user": { "login": "mara" },
             "created_at": "2026-05-31T12:00:00Z",
         });
-        assert_eq!(captured(&ev), "**mara @ 2026-05-31T12:00:00Z**: closed");
+        assert_eq!(format_event(&ev), "**mara @ 2026-05-31T12:00:00Z**: closed");
+    }
+
+    #[test]
+    fn assignees_added_and_removed() {
+        let added = serde_json::json!({
+            "type": "assignees",
+            "user": { "login": "triage" },
+            "created_at": "2026-05-31T12:00:00Z",
+            "assignee": { "login": "damocles" },
+            "removed_assignee": false,
+        });
+        assert_eq!(
+            format_event(&added),
+            "**triage @ 2026-05-31T12:00:00Z**: assigned @damocles"
+        );
+        let removed = serde_json::json!({
+            "type": "assignees",
+            "user": { "login": "triage" },
+            "created_at": "2026-05-31T12:00:00Z",
+            "assignee": { "login": "damocles" },
+            "removed_assignee": true,
+        });
+        assert_eq!(
+            format_event(&removed),
+            "**triage @ 2026-05-31T12:00:00Z**: unassigned @damocles"
+        );
+    }
+
+    #[test]
+    fn pull_push_counts_commits_and_marks_force() {
+        let normal = serde_json::json!({
+            "type": "pull_push",
+            "user": { "login": "damocles" },
+            "created_at": "2026-05-31T12:00:00Z",
+            "body": r#"{"is_force_push":false,"commit_ids":["a","b","c"]}"#,
+        });
+        assert_eq!(
+            format_event(&normal),
+            "**damocles @ 2026-05-31T12:00:00Z**: pushed 3 commit(s)"
+        );
+        let forced = serde_json::json!({
+            "type": "pull_push",
+            "user": { "login": "damocles" },
+            "created_at": "2026-05-31T12:00:00Z",
+            "body": r#"{"is_force_push":true,"commit_ids":["a"]}"#,
+        });
+        assert_eq!(
+            format_event(&forced),
+            "**damocles @ 2026-05-31T12:00:00Z**: force-pushed 1 commit(s)"
+        );
+    }
+
+    #[test]
+    fn commit_ref_truncates_sha_to_seven() {
+        let ev = serde_json::json!({
+            "type": "commit_ref",
+            "user": { "login": "damocles" },
+            "created_at": "2026-05-31T12:00:00Z",
+            "ref_commit_sha": "abcdef0123456789abcdef0123456789abcdef01",
+        });
+        assert_eq!(
+            format_event(&ev),
+            "**damocles @ 2026-05-31T12:00:00Z**: referenced from commit abcdef0"
+        );
     }
 
     #[test]
@@ -287,7 +333,7 @@ mod tests {
             "created_at": "2026-05-31T12:00:00Z",
         });
         assert_eq!(
-            captured(&ev),
+            format_event(&ev),
             "**ci-bot @ 2026-05-31T12:00:00Z**: [deploy_status]"
         );
     }
@@ -299,6 +345,6 @@ mod tests {
             "type": "close",
             "created_at": "2026-05-31T12:00:00Z",
         });
-        assert_eq!(captured(&ev), "**? @ 2026-05-31T12:00:00Z**: closed");
+        assert_eq!(format_event(&ev), "**? @ 2026-05-31T12:00:00Z**: closed");
     }
 }