Test with the hyphen that can be broken across lines: abcd‐efgh‐ijkl‐mnop‐qrst‐uvwx abcd‐efgh‐ijkl‐mnop‐qrst‐uvwx abcd‐efgh‐ijkl‐mnop‐qrst‐uvwx abcd‐efgh‐ijkl‐mnop‐qrst‐uvwx abcd‐efgh‐ijkl‐mnop‐qrst‐uvwx abcd‐efgh‐ijkl‐mnop‐qrst‐uvwx abcd‐efgh‐ijkl‐mnop‐qrst‐uvwx abcd‐efgh‐ijkl‐mnop‐qrst‐uvwx abcd‐efgh‐ijkl‐mnop‐qrst‐uvwx abcd‐efgh‐ijkl‐mnop‐qrst‐uvwx abcd‐efgh‐ijkl‐mnop‐qrst‐uvwx

Reference: Unicode 4.0, Section 6.2.