Truncate invisible lines before storing ref-tests

Because there is no good way to store invisible lines in a backwards-
and forwards-compatible way, they buffer now gets truncated before
dumping the state of a grid when creating a ref-test.

This involved a few workaround of which a few required adding additional
methods which are only used in ref-tests, these should be minimal
though.

Since this required the creation of a truncation method anyways, some
logic has been added which automatically truncates the invisible buffer
when there are more than X (set to 100) invisible lines. This should not
impact performance because it rarely occurs, but it could save a bit of
memory when the history size is shrunk during runtime (see #1293).

This also adds an optional `config.json` file to the ref-test output
where it is possible to manually specify variables which should override
config defaults, this has been used only for history_size so far.

Creating a new ref-test does also still work, so there was no regression
here, if history size is altered, the config.json just has to be created
manually with the content `{"history_size":HIST_SIZE}`, where
`HIST_SIZE` is the desired history size.

1 files changed, 2 insertions, 1 deletions

diff --git a/src/event.rs b/src/event.rs
index cf7d1030..37e4eccf 100644
--- a/src/event.rs
+++ b/src/event.rs
@@ -271,7 +271,8 @@ impl<N: Notify> Processor<N> {
                     CloseRequested => {
                         if ref_test {
                             // dump grid state
-                            let grid = processor.ctx.terminal.grid();
+                            let mut grid = processor.ctx.terminal.grid().clone();
+                            grid.truncate();
 
                             let serialized_grid = json::to_string(&grid)
                                 .expect("serialize grid");