package app

import (
	"strings"
	"testing"
)

// F-006: a multi-line paste must collapse to a single display line so the fixed-height
// input box can't overflow and leave a smeared/stale region.
func TestFlattenForDisplay(t *testing.T) {
	cases := map[string]string{
		"plain text":         "plain text",
		"line one\nline two": "line one↵ line two",
		"crlf\r\nhere":       "crlf↵ here",
		"tab\tseparated":     "tab separated",
		"a\nb\nc":            "a↵ b↵ c",
	}
	for in, want := range cases {
		if got := flattenForDisplay(in); got != want {
			t.Errorf("flattenForDisplay(%q) = %q, want %q", in, got, want)
		}
		if strings.ContainsAny(flattenForDisplay(in), "\n\r\t") {
			t.Errorf("flattenForDisplay(%q) still contains a control char", in)
		}
	}
}