Snapshots leave out a blank cell's ink, which shows nowhere and the tty now keeps from the frame before

1 files changed, 30 insertions, 1 deletions

diff --git a/test/snapshot.zig b/test/snapshot.zig
index c49e7645..0514d8d8 100644
--- a/test/snapshot.zig
+++ b/test/snapshot.zig
@@ -1330,9 +1330,28 @@ fn styleRows(arena: std.mem.Allocator, h: *eh.Harness) ![]const []const u8 {
         var run_key: [64]u8 = undefined;
         var run_len: usize = 0;
         var run_start: u16 = 0;
+        // A blank's ink shows nowhere, and the tty leaves whatever ink the
+        // terminal had there (tty.zig blankInk), so it depends on the frames
+        // before: a blank is written with the ink of the cell before it.
+        var ink_buf: [16]u8 = undefined;
+        var ink: []const u8 = "d";
         var x: u16 = 0;
         while (x <= h.cols) : (x += 1) {
-            const key: []const u8 = if (x == h.cols) "\x00end" else cellKey(h, x, y, &key_buf);
+            var key: []const u8 = if (x == h.cols) "\x00end" else cellKey(h, x, y, &key_buf);
+            if (x < h.cols) {
+                const comma = std.mem.indexOfScalar(u8, key, ',') orelse key.len;
+                if (inklessBlank(h, x, y)) {
+                    var joined: [64]u8 = undefined;
+                    const rest = key[comma..];
+                    @memcpy(joined[0..ink.len], ink);
+                    @memcpy(joined[ink.len..][0..rest.len], rest);
+                    @memcpy(key_buf[0 .. ink.len + rest.len], joined[0 .. ink.len + rest.len]);
+                    key = key_buf[0 .. ink.len + rest.len];
+                } else {
+                    @memcpy(ink_buf[0..comma], key[0..comma]);
+                    ink = ink_buf[0..comma];
+                }
+            }
             if (x == 0) {
                 @memcpy(run_key[0..key.len], key);
                 run_len = key.len;
@@ -1350,6 +1369,16 @@ fn styleRows(arena: std.mem.Allocator, h: *eh.Harness) ![]const []const u8 {
     return out;
 }
 
+/// A cell whose ink shows nowhere: no text but a space, and no underline,
+/// strike or reverse to draw with it.
+fn inklessBlank(h: *eh.Harness, x: u16, y: u16) bool {
+    const ci = h.term.screens.active.pages.getCell(.{ .viewport = .{ .x = x, .y = y } }) orelse return false;
+    if (ci.cell.wide == .spacer_tail) return false;
+    if (ci.cell.hasText() and ci.cell.codepoint() != ' ') return false;
+    const flags = ci.style().flags;
+    return !flags.inverse and !flags.strikethrough and flags.underline == .none;
+}
+
 fn cellKey(h: *eh.Harness, x: u16, y: u16, buf: *[64]u8) []const u8 {
     const ci = h.term.screens.active.pages.getCell(.{ .viewport = .{ .x = x, .y = y } }) orelse return "d,d,";
     if (ci.cell.wide == .spacer_tail) return "d,d,";