message: Protect a line of code that wasn't mutation-proof.
  Improves branch coverage.
diff: @@ -1585,6 +1585,13 @@ static const std::initializer_list<FormatterTestCase> kFormatterTestCases = {
  " input logic z\n"
  ");\n"
  "endinterface\n"},
  + {// interface declaration with multiple ports
  + " interface if1( input\tlogic z, output logic a)\n;endinterface\t\t",
  + "interface if1 (\n"
  + " input logic z,\n" // should be one-per-line, even it it fits
  + " output logic a\n"
  + ");\n"
  + "endinterface\n"},
  {// interface declaration with parameters and ports
  " interface if1#( parameter int W= 8 )(input logic z);endinterface\t\t",
  // doesn't fit on one line
  