package util

import "testing"

// Written as a code point so that it is visible in the source rather than
// looking like an ordinary space.
const nonBreakingSpace = string(rune(0x00a0))

func TestCollapseWhitespace(t *testing.T) {
	tests := []struct {
		name     string
		input    string
		expected string
	}{
		{"nothing to change", "one two", "one two"},
		{"leading and trailing spaces", "  one two  ", "one two"},
		{"run in the middle", "one    two", "one two"},
		{"tabs and newlines", "one\t\ttwo\nthree", "one two three"},
		{"windows line endings", "one\r\ntwo", "one two"},
		{"non-breaking space", "one" + nonBreakingSpace + "two", "one two"},
		{"mixed whitespace run", "one \t" + nonBreakingSpace + " two", "one two"},
		{"only whitespace", " \t\n ", ""},
		{"empty string", "", ""},
		{"single word with padding", "\tword\n", "word"},
		{"paragraph becomes one line", "first line\n\nsecond line\n", "first line second line"},
	}

	for _, test := range tests {
		t.Run(test.name, func(t *testing.T) {
			got := CollapseWhitespace(test.input)
			if got != test.expected {
				t.Errorf("expected %q got %q", test.expected, got)
			}
		})
	}
}