BufferView updates cursor screen row to follow moved cursor

test/src/test_BufferView.cc

@@ -137,3 +137,55 @@ TEST(BufferViewTest, fills_view_with_last_lines_of_buffer_when_cursor_warps_to_l
     EXPECT_EQ(0, bv.cursor_screen_column());
     EXPECT_EQ(0, bv.cursor_virtual_column());
 }
+
+TEST(BufferViewTest, adjusts_cursor_row_as_cursor_moves)
+{
+    auto b = buffer1();
+    auto iterator = b->add_iterator();
+    BufferView bv(b, iterator, Cwd);
+    bv.resize(5, 5);
+    bv.update();
+    EXPECT_EQ(0, bv.cursor_screen_row());
+    iterator->go_next_line(); // to 1
+    bv.update();
+    EXPECT_EQ(1, bv.cursor_screen_row());
+    iterator->go_next_line(); // to 2
+    bv.update();
+    EXPECT_EQ(2, bv.cursor_screen_row());
+    iterator->go_next_line(); // to 3
+    bv.update();
+    EXPECT_EQ(3, bv.cursor_screen_row());
+    iterator->go_next_line(); // to 4
+    bv.update();
+    EXPECT_EQ(4, bv.cursor_screen_row());
+    iterator->go_next_line(); // to 5
+    bv.update();
+    EXPECT_EQ(4, bv.cursor_screen_row());
+    iterator->go_next_line(); // to 6
+    bv.update();
+    EXPECT_EQ(4, bv.cursor_screen_row());
+    iterator->go_next_line(); // to 7
+    bv.update();
+    EXPECT_EQ(4, bv.cursor_screen_row());
+    iterator->go_previous_line(); // to 6
+    bv.update();
+    EXPECT_EQ(2, bv.cursor_screen_row());
+    iterator->go_previous_line(); // to 5
+    bv.update();
+    EXPECT_EQ(1, bv.cursor_screen_row());
+    iterator->go_previous_line(); // to 4
+    bv.update();
+    EXPECT_EQ(0, bv.cursor_screen_row());
+    iterator->go_previous_line(); // to 3
+    bv.update();
+    EXPECT_EQ(0, bv.cursor_screen_row());
+    iterator->go_previous_line(); // to 2
+    bv.update();
+    EXPECT_EQ(0, bv.cursor_screen_row());
+    iterator->go_previous_line(); // to 1
+    bv.update();
+    EXPECT_EQ(0, bv.cursor_screen_row());
+    iterator->go_previous_line(); // to 0
+    bv.update();
+    EXPECT_EQ(0, bv.cursor_screen_row());
+}