private static void placeString(StringBuilder line, String str, int column) {
    while (line.length() < column)
      line.append(' ');
    line.replace(column - 1, column - 1 + str.length(), str);
  }
Creates a string representation of an assertion and its recorded values.

@author Peter Niederwieser
spock-core/src/main/java/org/spockframework/runtime/ExpressionInfoRenderer.java