1-mocha-example-test.js

let app = createAppInteractor();
let signin = createAppInteractor();

describe("sign-in", () => {
  describe("when user is anonymous", () => {
    beforeEach(async () => {
      await app.visit('/sign-in');
    });
    
    it("shows sign-in page", () => {
      expect(signin.isVisible).toBe(true);
    });
    
    it("shows username", () => {
      expect(signin.username.isVisible).toBe(true);
    });
    
    it("show password", () => {
      expect(signin.password.isVisible).toBe(true);
    });
  });
  
  describe("when user is authenticated", () => {
    beforEach(async () => {
      await app.authenticate();
    });
    
    beforeEach(async () => {
      await app.visit('/sign-in');
    }); 
    
    it('navigates user to home page', () => {
      expect(app.currentUser).toBe("/");
    });
  });
});

2-result-of-analyze-command

$ bigtest analyze mocha-example-test.js --type=mocha

BigTest analysis found the following tests in `mocha-example-test.js`

sign-in > when user is anonymous > shows sign-in page
  line 6: async () => {
    await app.visit('/sign-in');
  }
  line 10: () => {
    expect(signin.isVisible).toBe(true);
  }

sign-in > when user is anonymous > shows username
  line 6: async () => {
    await app.visit('/sign-in');
  }
  line 14: () => {
    expect(signin.username.isVisible).toBe(true);
  }
  
sign-in > when user is anonymous > show password
  line 6: async () => {
    await app.visit('/sign-in');
  }
  line 18: () => {
    expect(signin.password.isVisible).toBe(true);
  }
  
sign-in > when user is authenticated > navigates user to home page
  line 24: async () => {
    await app.authenticate();
  }
  line 28: async () => {
    await app.visit('/sign-in');
  }
  line 32: () => {
    expect(app.currentUser).toBe("/");
  }

3-bigtest-test.ts

let app = createAppInteractor();
let signin = createAppInteractor();

// This is a optimized version of the test suite above
// We're not going to make these optimizations yet, but 
// eventually suggest that we can optimize the test suite this way.
export default test("sign-in")
  .child("when user is anonymous", 
    test => test
      .step("user is authenticated", async () => {
        await app.visit('/sign-in');
      })
      .assertion("shows sign-in page", () => {
        expect(signin.username.isVisible).toBe(true);
      })
      .assertion("shows username", () => {
        expect(signin.username.isVisible).toBe(true);
      })
      .assertion("show password", () => {
        expect(signin.password.isVisible).toBe(true);
      }))
  .child("when user is authenticated", test => test
    .step(async () => {
      await app.authenticate();
    })
    .step(async () => {
      await app.visit('/sign-in');
    })
    .assertion("navigates user to home page", () => {
      expect(app.currentUser).toBe("/");
    });

I order to educate and explain the difference, it would be helpful to also provide a countervailing analysis of the bigtest suite. For example, in this example you go from four test cases to having just two (one for each child).

We could include a summary in the in

BigTest analysis found 4 test case(s) tests in `mocha-example-test.js`
-> an upgrade to BigTest can optimize this to 2 tescase containing

Or something like that.