循环遍历数组并对每个元素运行 Jest 测试不起作用

Question

我有一个非常大的 JSON 对象数组。我需要对每个单独的元素运行 Jest 测试。我尝试首先迭代数组，然后在循环中编写测试，如下所示：

describe("Tests", (f) => {
  it("has all fields and they are valid", () => {
    expect(f.portions! >= 0).toBeTruthy();
    expect(f.name.length > 0 && typeof f.name === "string").toBeTruthy();
  });

  it("has an image", () => {
    expect(f.image).toBeTruthy();
  });
});

然而，对于这段代码，Jest 抱怨“你的测试套件必须至少包含一个测试”。

我是否必须为每个测试循环遍历这个数组？

Answer 1

Jest 确实有describe.each、test.each和it.each满足您需求的方法。它允许您使用不同的输入/输出进行相同的测试。

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https://jestjs.io/docs/api#describeeachtablename-fn-timeout

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例子 ：

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使用全局描述.each：

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const params = [\n  [true, false, false],\n  [true, true, true],\n  [false, true, false],\n  [false, false, true],\n];\n\ndescribe.each(params)(\'With params %s, %s, %s\', (a, b, c) => {\n  it(`${a} === ${b} should be ${c}`, () => {\n    expect(a === b).toBe(c);\n  });\n});\n

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输出 ：

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 PASS  test/integration-tests/test.spec.ts (5.938s)\n  With params true, false, false\n    \xe2\x88\x9a true === false should be false (2ms)\n  With params true, true, true\n    \xe2\x88\x9a true === true should be true\n  With params false, true, false\n    \xe2\x88\x9a false === true should be false (1ms)\n  With params false, false, true\n    \xe2\x88\x9a false === false should be true\n

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或者使用简单的 it.each ：

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 PASS  test/integration-tests/test.spec.ts (5.938s)\n  With params true, false, false\n    \xe2\x88\x9a true === false should be false (2ms)\n  With params true, true, true\n    \xe2\x88\x9a true === true should be true\n  With params false, true, false\n    \xe2\x88\x9a false === true should be false (1ms)\n  With params false, false, true\n    \xe2\x88\x9a false === false should be true\n

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输出 ：

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 PASS  test/integration-tests/test.spec.ts\n  Dumb test\n    \xe2\x88\x9a true === false should be false (2ms)\n    \xe2\x88\x9a true === true should be true\n    \xe2\x88\x9a false === true should be false\n    \xe2\x88\x9a false === false should be true\n

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