Comedy Central host Stephen Colbert is slated to testify at a congressional hearing Friday on immigration titled “Protecting America’s Harvest,” two sources have told The Daily Caller. One Republican source said Colbert will be testifying “in character,” the Bill O’Reilly-like muse Colbert uses for his show. A Judiciary Committee spokeswoman, confirming Colbert would testify, said the hearing matter was a “serious issue . . . this is not a TV stunt.” Some Republicans have already expressed unhappiness with Colbert witnessing at the hearing, thinking it would make light of a serious issue. The hearing is before the House Judiciary Committee’s...