如何编写一个函数来通过 2 个测试

Question

我正在学习和练习使用 javascript 编写测试：

这是测试用例find.test.js ：

var findTheNeedle = require("./find-needle");

test("Find the needle", function () {
  var words = ["house", "train", "slide", "needle", "book"];
  var expected = 3;

  var output = findTheNeedle(words, "needle");

  expect(output).toEqual(expected);
});

test("Find the plant", function () {
  var words = ["plant", "shelf", "arrow", "bird"];
  var expected = 0;

  var output = findTheNeedle(words, "plant");

  expect(output).toEqual(expected);
});

这是我的以下函数find.js ：

function findNeedle(words) {
  for (var i = 0; i < words.length; i++) {
    if (words[i] === "needle") {
      var needle = i;
    }
  }

  return needle;
}
module.exports = findNeedle;

Answer 1

你应该做这个：

var findTheNeedle = require("./find-needle");

test("Find the object", function () {
  var words = ["house", "train", "slide", "needle", "book"];
  var expected = 3;

  var output = findTheNeedle(words, "needle");

  expect(output).toEqual(expected);

  var words = ["plant", "shelf", "arrow", "bird"];
  var expected = 0;

  var output = findTheNeedle(words, "plant");

  expect(output).toEqual(expected);
});

我认为您需要重新制作该功能，如下所示：

function findInArray( arr, word ) {
  let index = -1
  for (var i = 0; i < arr.length; i++) {
    if (arr[i] === word) {
       index = i;
    }
  }

  return index;
}
module.exports = findInArray;

如果任何“期望”失败，则所有测试都将失败

Answer 2

看来您的函数将返回单词列表中“单词”的索引。 这意味着，您的函数必须接收 2 个变量作为参数：“word”和“words”。

我认为当前的函数名（和文件名） - findNeedle不“正确”，所以我建议更改它。 findWordIndex怎么样？

函数逻辑很简单，你可以使用Array.indexOf工具来做，或者按照你的方式来做。

module.exports = (words, word) => words.indexOf(word);

或者

module.exports = (words, word) => {
  for (let i = 0; i < words.length; i++) {
    if (words[i] === word) {
      return i; // stop right after you found it
    }
  }
  return -1;
};