Rspec "expect" snippets found on Stackoverflow

gistfile1.txt

expect { thing.destroy }.to change(Thing, :count).from(1).to(0)
expect { thing.tax = 5 }.to change { thing.total_price }.by(5)
expect { thing.save! }.to raise_error
expect { thing.symbolize_name }.to change { thing.name }.from(String).to(Symbol)