参数化验证

参数化验证是什么

参数化验证，即指提供在多个 test cases 中重用相同测试逻辑的方法。

参数化验证要解决的问题

比如我们要测试下面的 emailValidator 函数：

export function emailValidator(email: string): boolean {
  const regex = /^[\w-]+(\.[\w-]+)*@([\w-]+\.)+[a-zA-Z]{2,7}$/;
  return regex.test(email);
}

很有可能就会写这样的测试代码：

describe("emailValidator", () => {
  it("should return true for a valid email", () => {
    const email = "valid-email@example.com";
    expect(emailValidator(email)).toBe(true);
  });

  it("should return false for a invalid email without domain extension", () => {
    const email = "valid-email@example";
    expect(emailValidator(email)).toBe(false);
  });

  it("should return false for a invalid email with extra dot at the end", () => {
    const email = "valid-email@example.";
    expect(emailValidator(email)).toBe(false);
  });

  it("should return false for a invalid email with missing '@'", () => {
    const email = "valid-email.example.com";
    expect(emailValidator(email)).toBe(false);
  });

  // ... ...
});

上面所有的 test cases 都是一样的逻辑，只是输入输出不一样。

使用参数化验证

参数化验证 - 数组

这个时候，就可以使用 vitest 提供的 it.each API 来处理：

describe("emailValidator", () => {
  it.each([
    ["valid-email@example.com", true],
    ["valid-email@example", false],
    ["valid-email@example.", false],
    ["valid-email.example.com", false],
  ])("should return %s when validating %s", (email, excepted) => {
    expect(emailValidator(email).toBe(excepted));
  });
});

注意，为了快速定位失败的测试用例，一定要使用占位符来写描述信息。

占位符：

%s - String. %d - Number (both integer and float). %j - JSON. %% - single percent sign ('%'). This does not consume an argument.

参数化验证 - 对象 :thumbsup:

describe("emailValidator", () => {
  it.each([
    { email: "valid-email@example.com", expected: true },
    { email: "valid-email@example", expected: false },
    { email: "valid-email@example.", expected: false },
    { email: "valid-email.example.com", expected: false },
  ])(
    "should return $email when validating $expected",
    ({ email, excepted }) => {
      expect(emailValidator(email).toBe(excepted));
    }
  );
});

如果是用对象来构建输入输出，那占位符可以使用 $parameter 的形式。

使用对象的方式可读性更高。

参数化验证 - 模板标签

describe("emailValidator", () => {
  it.each`
    "email"                      | "expected"
    ${"valid-email@example.com"} | ${true}
    ${"valid-email@example"}     | ${false}
    ${"valid-email@example."}    | ${false}
    ${"valid-email.example.com"} | ${false}
  `("should return $email when validating $expected", ({ email, excepted }) => {
    expect(emailValidator(email).toBe(excepted));
  });
});