fails:String#encoding for US-ASCII Strings returns US-ASCII if self is US-ASCII
fails:String#encoding for US-ASCII Strings returns US-ASCII if self is US-ASCII only, despite the default internal encoding being different
fails:String#encoding for US-ASCII Strings returns US-ASCII if self is US-ASCII only, despite the default external encoding being different
fails:String#encoding for US-ASCII Strings returns US-ASCII if self is US-ASCII only, despite the default internal and external encodings being different
fails:String#encoding for US-ASCII Strings returns US-ASCII if self is US-ASCII only, despite the default encodings being different
fails:String#encoding for Strings with \u escapes returns UTF-8
fails:String#encoding for Strings with \u escapes returns US-ASCII if self is US-ASCII only
fails:String#encoding for Strings with \u escapes returns UTF-8 if self isn't US-ASCII only
fails:String#encoding for Strings with \u escapes is not affected by the default internal encoding
fails:String#encoding for Strings with \u escapes is not affected by the default external encoding
fails:String#encoding for Strings with \u escapes is not affected by both the default internal and external encoding being set at the same time
fails:String#encoding for Strings with \x escapes returns US-ASCII if self is US-ASCII only
fails:String#encoding for Strings with \x escapes returns ASCII-8BIT when an escape creates a byte with the 8th bit set if the source encoding is US-ASCII
fails:String#encoding for Strings with \x escapes returns the source encoding when an escape creates a byte with the 8th bit set if the source encoding isn't US-ASCII
fails:String#encoding for Strings with \x escapes is not affected by the default internal encoding
fails:String#encoding for Strings with \x escapes is not affected by the default external encoding
fails:String#encoding for Strings with \x escapes is not affected by both the default internal and external encoding being set at the same time
