如何通过在函数中提取部分代码或在 Jest 中使用它来减少测试中的重复代码

Question

我被要求通过使用 it.each 或创建一个函数来减少测试中的重复。我不知道该怎么做。我在测试套件中还有其他预计不会出错的功能。我假设我可以将下面两个重复的断言放在辅助函数中，但如果您有更好的建议，请告诉我。谢谢。

expect(<jest.Mock>fetch).not.toHaveBeenCalled();
expect(e).toBeInstanceOf(TypeError);

测试文件：

it('should throw if no args were passed', async () => {
            expect.assertions(3);
            return readPricing().catch((e: Error) => {
                expect(<jest.Mock>fetch).not.toHaveBeenCalled();
                expect(e).toBeInstanceOf(TypeError);
                expect(e.message).toBe(
                    `The 'products' information is required to successfully be able to execute this request.`
                );
            });
        });

        it('should throw if no product IDs were passed', () => {
            expect.assertions(3);
            const noIdData = {
                products: [{ salesPrice: '60.00' }, { salesPrice: '80.00' }],
            };
            // @ts-expect-error
            return readPricing(noIdData).catch((e: Error) => {
                expect(<jest.Mock>fetch).not.toHaveBeenCalled();
                expect(e).toBeInstanceOf(TypeError);
                expect(e.message).toBe(`The 'productId' is required to successfully be able to execute this request.`);
            });
        });

        it('should throw if an empty array of products was passed', () => {
            expect.assertions(3);
            const noIdData = { products: [] };
            return readPricing(noIdData).catch((e: Error) => {
                expect(<jest.Mock>fetch).not.toHaveBeenCalled();
                expect(e).toBeInstanceOf(TypeError);
                expect(e.message).toBe(
                    `The 'products' information is required to successfully be able to execute this request.`
                );
            });
        });

我尝试使用它。每个但未能成功设置它，我不确定给定的输入是否可行。

Answer 1

it.each()

应该做的伎俩，你可以实现这样的事情：

describe("temp", () => {
  const productInfoMissingErr = `The 'products' information is required to successfully be able to execute this request.`;
  const productIdMissingErr = `The 'products' information is required to successfully be able to execute this request.`;
  const noIdData = {
    products: [{ salesPrice: "60.00" }, { salesPrice: "80.00" }],
  };

  it.each([
    ["no args were passed", undefined, productInfoMissingErr],
    ["no product IDs were passed", noIdData, productInfoMissingErr],
    [
      "an empty array of products was passed",
      { products: [] },
      productIdMissingErr,
    ],
  ])("should throw if %s", (caseTitle, input, errMsg) => {
    return readPricing().catch((e: Error) => {
      expect.assertions(3);
      expect(<jest.Mock>fetch).not.toHaveBeenCalled();
      expect(e).toBeInstanceOf(TypeError);
      expect(e.message).toBe(errMsg);
    });
  });
});

应该呈现相同的消息：

  temp
    ✓ should throw if no args were passed (1 ms)
    ✓ should throw if no product IDs were passed
    ✓ should throw if an empty array of products was passed (1 ms)

Test Suites: 1 passed, 1 total
Tests:       3 passed, 3 total
Snapshots:   0 total
Time:        0.226 s, estimated 1 s
Ran all test suites.