describe("mocha before hooks", function () {
  before(() => console.log("*** top-level before()"));
  beforeEach(() => console.log("*** top-level beforeEach()"));
  describe("nesting", function () {
    before(() => console.log("*** nested before()"));
    beforeEach(() => console.log("*** nested beforeEach()"));
    it("is a nested spec", () => true);
  });
});

Output:

//   mocha before hooks
// *** top-level before()
//     nesting
// *** nested before()
// *** top-level beforeEach()
// *** nested beforeEach()
//       ✓ is a nested spec
//
//
//   1 passing (8ms)

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Referenced from GitHub Gist by harto