export function fun1(number) {
    if (number < 0)
        number = number * (-1);
    return number;
}

describe('fun1', () => {
    it('test1', () => {
        const result = fun1(-1);
        expect(result).toBe(1);
    })
    ...
})

it('test2', () => {
    const result = fun1(1);
    expect(result).toBe(result+1);
})

it('test2', () => {
    const result = fun1(2);
    expect(result).toBe(-2);
})

it('test2', () => {
    const result = fun1(2);
    expect(result).toBe(2);
})

it('test2', () => {
    const result = fun1(1);
    expect(result).toBe(-1);
})