As preview performances of "Harry Potter and the Cursed Child" began last week in London ahead of the play's July 30 opening, author J.K. Rowling again expressed frustration at resistance from some fans to casting a black actress as the adult Hermione.

Rowling described Noma Dumezweni, who won the 2006 Olivier Award for Best Supporting Actress for her performance in "A Raisin in the Sun" as "the best actress for the job."

"I had a bunch of racists telling me that because Hermione ‘turned white’ – that is, lost color from her face after a shock – that she must be a white woman, which I have a great deal of difficulty with," she told The Observer. "But I decided not to get too agitated about it and simply state quite firmly that Hermione can be a black woman with my absolute blessing and enthusiasm."

Director John Tiffany also expressed dismay that "people couldn’t visualize a nonwhite person as the hero of a story," making Dumezweni's casting, then, an excellent opportunity.

Rowling supported the casting choice from the start, noting following the announcement in December that Hermione was never characterized as white in the "Harry Potter" novels:

Canon: brown eyes, frizzy hair and very clever. White skin was never specified. Rowling loves black Hermione https://t.co/5fKX4InjTH

— J.K. Rowling (@jk_rowling) December 21, 2015

"Harry Potter and the Cursed Child Parts 1 and 2," overseen by Rowling but written by Jack Thorne, picks up after the epilogue to "Harry Potter and the Deathly Hallows. The play features grown-up versions of Harry, Ron, Hermione and company, though Harry's youngest son Albus is said to be at the heart of the story.

Scholastic will publish a "Special Rehearsal Edition" of the script in the United States  to coincide with the theatrical opening, while Little, Brown will publish the script in the United Kingdom.