Fix hidden line on non-body line addition

When a leading, trailing or header line was added to the view data, the
RenderSlice was not correctly updated to take into account which lines
should be visible. This resulted in some lines being hidden below the
view "window". This fixes the RenderSlice to recalculate the scroll
position when a leading, trailing or header line is changed.

CHANGELOG.md

@@ -15,6 +15,7 @@ The format is based on [Keep a Changelog](http://keepachangelog.com/).
 - Fixed TTY support on macOS ([#874](https://github.com/MitMaro/git-interactive-rebase-tool/pull/874))
 - Flicker when action width changes ([#888](https://github.com/MitMaro/git-interactive-rebase-tool/pull/891))
 - Selected line was not always visible when multiple lines were selected ([#918](https://github.com/MitMaro/git-interactive-rebase-tool/pull/918))
+- Selected line hidden by added trailing, leading or header line when view was not resized ([#919](https://github.com/MitMaro/git-interactive-rebase-tool/pull/919))
 
 ## [2.3.0] - 2023-07-19
 ### Added

src/view/render_slice.rs

@@ -218,6 +218,7 @@ impl RenderSlice {
 
 		if self.padding_height != padding_height {
 			self.padding_height = padding_height;
+			self.update_scroll_position_size();
 		}
 	}
 

src/view/tests.rs

@@ -1,19 +1,23 @@
 use super::*;
 use crate::{config::Theme, display::Size, test_helpers::mocks};
 
-fn assert_render(width: usize, height: usize, view_data: &ViewData, expected: &[&str]) {
+fn assert_render_slice(width: usize, height: usize, render_slice: &RenderSlice, expected: &[&str]) {
 	let theme = Theme::new_with_config(None).unwrap();
 	let mut crossterm = mocks::CrossTerm::new();
 	let readonly_tui = crossterm.clone();
 	crossterm.set_size(Size::new(width, height));
 	let display = Display::new(crossterm, &theme);
 	let mut view = View::new(display, "~", "?");
 
+	view.render(&render_slice).unwrap();
+	assert_eq!(readonly_tui.get_output().join(""), format!("{}\n", expected.join("\n")));
+}
+
+fn assert_render(width: usize, height: usize, view_data: &ViewData, expected: &[&str]) {
 	let mut render_slice = RenderSlice::new();
 	render_slice.record_resize(width, height);
 	render_slice.sync_view_data(view_data);
-	view.render(&render_slice).unwrap();
-	assert_eq!(readonly_tui.get_output().join(""), format!("{}\n", expected.join("\n")));
+	assert_render_slice(width, height, &render_slice, expected);
 }
 
 #[test]
@@ -235,3 +239,66 @@ fn render_ensure_visible_multiple_rows_decreasing_order() {
 		&["This is line 3 ", "This is line 4 ", "This is line 5█"],
 	);
 }
+
+#[test]
+fn render_after_leading_lines_change() {
+	let width = 30;
+	let height = 2;
+	let mut render_slice = RenderSlice::new();
+	render_slice.record_resize(width, height);
+	let mut view_data = ViewData::new(|updater| {
+		updater.push_line(ViewLine::from("This is line 1"));
+		updater.push_line(ViewLine::from("This is line 2"));
+		updater.push_line(ViewLine::from("This is line 3"));
+		updater.ensure_line_visible(2);
+	});
+	render_slice.sync_view_data(&view_data);
+	view_data.update_view_data(|updater| {
+		updater.push_leading_line(ViewLine::from("This is line 0"));
+	});
+	render_slice.sync_view_data(&view_data);
+	assert_render_slice(width, height, &render_slice, &["This is line 0", "This is line 3█"]);
+}
+
+#[test]
+fn render_after_title_show() {
+	let width = 30;
+	let height = 2;
+	let mut render_slice = RenderSlice::new();
+	render_slice.record_resize(width, height);
+	let mut view_data = ViewData::new(|updater| {
+		updater.push_line(ViewLine::from("This is line 1"));
+		updater.push_line(ViewLine::from("This is line 2"));
+		updater.push_line(ViewLine::from("This is line 3"));
+		updater.ensure_line_visible(2);
+	});
+	render_slice.sync_view_data(&view_data);
+	view_data.update_view_data(|updater| {
+		updater.set_show_title(true);
+	});
+	render_slice.sync_view_data(&view_data);
+	assert_render_slice(width, height, &render_slice, &[
+		"Git Interactive Rebase Tool   ",
+		"This is line 3█",
+	]);
+}
+
+#[test]
+fn render_after_trailing_lines_change() {
+	let width = 30;
+	let height = 2;
+	let mut render_slice = RenderSlice::new();
+	render_slice.record_resize(width, height);
+	let mut view_data = ViewData::new(|updater| {
+		updater.push_line(ViewLine::from("This is line 1"));
+		updater.push_line(ViewLine::from("This is line 2"));
+		updater.push_line(ViewLine::from("This is line 3"));
+		updater.ensure_line_visible(2);
+	});
+	render_slice.sync_view_data(&view_data);
+	view_data.update_view_data(|updater| {
+		updater.push_trailing_line(ViewLine::from("This is line 4"));
+	});
+	render_slice.sync_view_data(&view_data);
+	assert_render_slice(width, height, &render_slice, &["This is line 3█", "This is line 4"]);
+}