BufferView: fix more scrolling problems

test/src/test_BufferView.cc

@@ -592,6 +592,49 @@ TEST(BufferViewTest, scrolls_the_view_up_and_down)
     EXPECT_EQ(5, bv.cursor_screen_row());
 }
 
+TEST(BufferViewTest, scrolls_the_view_up_and_down_with_wrapped_lines)
+{
+    auto b = buffer1();
+    auto iterator = b->add_iterator();
+    BufferView bv(b, iterator, Cwd);
+    bv.resize(4, 2);
+    bv.update();
+    EXPECT_EQ(0, LineNumber(iterator));
+    EXPECT_EQ(0, bv.cursor_screen_row());
+    bv.scroll_view_down(6, false);
+    bv.update();
+    EXPECT_EQ(6, LineNumber(iterator));
+    EXPECT_EQ(C('6'), **iterator);
+    EXPECT_EQ(0, bv.cursor_screen_row());
+    bv.scroll_view_down(1, false);
+    bv.update();
+    EXPECT_EQ(6, LineNumber(iterator));
+    EXPECT_EQ(C('d'), **iterator);
+    bv.scroll_view_down(1, false);
+    bv.update();
+    EXPECT_EQ(7, LineNumber(iterator));
+    EXPECT_EQ(C('7'), **iterator);
+    bv.scroll_view_down(4, false);
+    bv.update();
+    EXPECT_EQ(9, LineNumber(iterator));
+    EXPECT_EQ(C('h'), **iterator);
+    bv.scroll_view_down(2, false);
+    bv.update();
+    EXPECT_EQ(10, LineNumber(iterator));
+    EXPECT_EQ(C('1'), **iterator);
+
+    bv.cursor_move(BufferView::CursorMovement::RIGHT, false);
+    bv.update();
+    bv.scroll_view_up(3, false);
+    bv.update();
+    EXPECT_EQ(9, LineNumber(iterator));
+    EXPECT_EQ(C('i'), **iterator);
+    bv.scroll_view_up(5, false);
+    bv.update();
+    EXPECT_EQ(6, LineNumber(iterator));
+    EXPECT_EQ(C('e'), **iterator);
+}
+
 TEST(BufferViewTest, scrolls_the_view_up_and_down_with_nonzero_scroll_offset)
 {
     auto b = buffer1();