chor: use new Writer interface for terminal's Writer; fix test cases

src/terminal.zig

@@ -62,17 +62,24 @@ pub fn write(buf: []const u8) !usize {
     return try posix.write(posix.STDIN_FILENO, buf);
 }
 
-fn contextWrite(context: *const anyopaque, data: []const u8) anyerror!usize {
-    _ = context;
-    return try posix.write(posix.STDOUT_FILENO, data);
+fn drainFn(w: *std.Io.Writer, data: []const []const u8, splat: usize) error{WriteFailed}!usize {
+    _ = w;
+    if (data.len == 0 or splat == 0) return 0;
+    var len: usize = 0;
+
+    for (data) |bytes| len += posix.write(posix.STDOUT_FILENO, bytes) catch return error.WriteFailed;
+
+    return len;
 }
 
-const Writer = std.io.AnyWriter;
-
-pub fn writer() Writer {
+// TODO I now need to add that much, for just the one function above?
+pub fn writer() std.Io.Writer {
     return .{
-        .context = &.{},
-        .writeFn = contextWrite,
+        .vtable = &.{
+            .drain = drainFn,
+            .flush = std.Io.Writer.noopFlush,
+        },
+        .buffer = &.{},
     };
 }
 
@@ -231,6 +238,7 @@ const log = std.log.scoped(.terminal);
 const std = @import("std");
 const mem = std.mem;
 const posix = std.posix;
+const assert = std.debug.assert;
 const ctlseqs = @import("ctlseqs.zig");
 const input = @import("input.zig");
 const Key = input.Key;