fails:String#<< converts the given argument to a String using to_str
fails:String#<< raises a TypeError if the given argument can't be converted to a String
fails:String#<< raises a RuntimeError when self is frozen
fails:String#<< taints self if other is tainted
fails:String#<< untrusts self if other is untrusted
fails:String#<< with Integer concatencates the argument interpreted as a codepoint
fails:String#<< with Integer returns a ASCII-8BIT string if self is US-ASCII and the argument is between 128-255 (inclusive)
fails:String#<< with Integer raises RangeError if the argument is an invalid codepoint for self's encoding
fails:String#<< with Integer raises RangeError if the argument is negative
fails:String#<< with Integer doesn't call to_int on its argument
fails:String#<< with Integer raises a RuntimeError when self is frozen
fails:String#<< when self is in an ASCII-incompatible encoding incompatible with the argument's encoding uses self's encoding if both are empty
fails:String#<< when self is in an ASCII-incompatible encoding incompatible with the argument's encoding uses self's encoding if the argument is empty
fails:String#<< when self is in an ASCII-incompatible encoding incompatible with the argument's encoding uses the argument's encoding if self is empty
fails:String#<< when self is in an ASCII-incompatible encoding incompatible with the argument's encoding raises Encoding::CompatibilityError if neither are empty
fails:String#<< when the argument is in an ASCII-incompatible encoding incompatible with self's encoding uses self's encoding if both are empty
fails:String#<< when the argument is in an ASCII-incompatible encoding incompatible with self's encoding uses self's encoding if the argument is empty
fails:String#<< when the argument is in an ASCII-incompatible encoding incompatible with self's encoding uses the argument's encoding if self is empty
fails:String#<< when the argument is in an ASCII-incompatible encoding incompatible with self's encoding raises Encoding::CompatibilityError if neither are empty
fails:String#<< when self and the argument are in different ASCII-compatible encodings uses self's encoding if both are ASCII-only
fails:String#<< when self and the argument are in different ASCII-compatible encodings uses self's encoding if the argument is ASCII-only
fails:String#<< when self and the argument are in different ASCII-compatible encodings uses the argument's encoding if self is ASCII-only
fails:String#<< when self and the argument are in different ASCII-compatible encodings raises Encoding::CompatibilityError if neither are ASCII-only
fails:String#<< when self is ASCII-8BIT and argument is US-ASCII uses ASCII-8BIT encoding
