Fix vim full line operations failing when no trailing newline (#24409)

Closes #24270

Release Notes:

- Fixed an issue where doing line-wise operations in vim mode on the
last line of a file with no trailing newline would not work properly

crates/vim/src/normal.rs

@@ -1545,4 +1545,40 @@ mod test {
         cx.simulate_shared_keystrokes("x escape shift-o").await;
         cx.shared_state().await.assert_eq("// hello\n// ˇ\n// x\n");
     }
+
+    #[gpui::test]
+    async fn test_yank_line_with_trailing_newline(cx: &mut gpui::TestAppContext) {
+        let mut cx = NeovimBackedTestContext::new(cx).await;
+        cx.set_shared_state("heˇllo\n").await;
+        cx.simulate_shared_keystrokes("y y p").await;
+        cx.shared_state().await.assert_eq("hello\nˇhello\n");
+    }
+
+    #[gpui::test]
+    async fn test_yank_line_without_trailing_newline(cx: &mut gpui::TestAppContext) {
+        let mut cx = NeovimBackedTestContext::new(cx).await;
+        cx.set_shared_state("heˇllo").await;
+        cx.simulate_shared_keystrokes("y y p").await;
+        cx.shared_state().await.assert_eq("hello\nˇhello");
+    }
+
+    #[gpui::test]
+    async fn test_yank_multiline_without_trailing_newline(cx: &mut gpui::TestAppContext) {
+        let mut cx = NeovimBackedTestContext::new(cx).await;
+        cx.set_shared_state("heˇllo\nhello").await;
+        cx.simulate_shared_keystrokes("2 y y p").await;
+        cx.shared_state()
+            .await
+            .assert_eq("hello\nˇhello\nhello\nhello");
+    }
+
+    #[gpui::test]
+    async fn test_dd_then_paste_without_trailing_newline(cx: &mut gpui::TestAppContext) {
+        let mut cx = NeovimBackedTestContext::new(cx).await;
+        cx.set_shared_state("heˇllo").await;
+        cx.simulate_shared_keystrokes("d d").await;
+        cx.shared_state().await.assert_eq("ˇ");
+        cx.simulate_shared_keystrokes("p p").await;
+        cx.shared_state().await.assert_eq("\nhello\nˇhello");
+    }
 }