如何在JavaScript中不同的参数值测试两个返回的功能呢？(How to test two re

我有一个返回comparisonFunction功能

  getComparisonFunction(propertyOfComparison) {
    const func = function(a, b){
      if ( a[propertyOfComparison] < b[propertyOfComparison] ) {
        return -1;
      }
      if ( a[propertyOfComparison] > b[propertyOfComparison] ) {
        return 1;
      }
      return 0;
    };

    return func;
  }

此方法将里面的javascript“分类”方法一起使用。例如：

arrayOfObjects.sort(getComparisonFunction('name'));

这种方法将“arrayOfObjects”的“名称”属性进行排序。方法工作正常，问题是：如何我可以比较函数调用不同的参数

  it('should get correct comparison function', function () {
    const func = component.getComparisonFunction('testProperty');

    const expectedFunc = function(a, b){
      if ( a['testProperty'] < b['testProperty'] ) {
        return -1;
      }
      if ( a['testProperty'] > b['testProperty'] ) {
        return 1;
      }
      return 0;
    };

    expect(func.toString()).toEqual(expectedFunc.toString());
  });

这是我现在有，但它没有工作。我运行代码后收到的错误：

 Expected 'function (a, b) {
                if (a[propertyOfComparison] < b[propertyOfComparison]) {
                    return -1;
                }
                if (a[propertyOfComparison] > b[propertyOfComparison]) {
                    return 1;
                }
                return 0;
            }' to equal 'function (a, b) {
                if (a['testProperty'] < b['testProperty']) {
                    return -1;
                }
                if (a['testProperty'] > b['testProperty']) {
                    return 1;
                }
                return 0;
            }'.

Answer 1:

检查函数的代码作为测试非常脆，容易折断给你一个假阴性：

 let someFn = function(a, b) { return a + b; } let expected = `function(a, b) { return a + b; }` console.log("Test original implementation:", test(someFn.toString(), expected)); //later the code style is changed to remove extra whitespace and make it one line someFn = function(a, b) { return a+b; } console.log("Test updated implementation:", test(someFn.toString(), expected)); //simple testing function test(expected, actual) { return expected == actual }

该代码打破了测试只是让非功能性的改变。

更糟糕的是，如果有对码功能的变化，测试不能保证新实现的行为类似于旧的，因为它只着眼于代码的结构：

 //simplified case of what the actual code could be doing function someCodeBaseFunction() { let someInput = [8, 12, 42]; return someFn(...someInput) } let someFn = function(a, b) { return a+b; } let expected = `function(a, b) { return a+b; }` console.log("Test original implementation:", test(someFn.toString(), expected)); console.log("Codebase usage:", someCodeBaseFunction()); //20, as the third number is ignored //new implementation someFn = function(...args) { return args.reduce((a, b) => a + b); } //update the test, so it passes expected = `function(...args) { return args.reduce((a, b) => a + b); }` console.log("Test updated implementation:", test(someFn.toString(), expected)); //some existing line of code console.log("Codebase usage:", someCodeBaseFunction()); //62, as the third number is now used //simple testing function test(expected, actual) { return expected == actual };

相反，你想要做什么测试代码的行为，并设置您的期望存在。这样一来，如果实现更改，可以确保执行仍符合同一组的期望。

在这种情况下，你需要创建一个样本输入端，最初是无序的，试图订购，然后想到的是，为了工作，你的预期。在伪代码，看起来有点像这样：

//arrange
input = [
 {testProperty: "c", id: 1},
 {testProperty: "a", id: 2},
 {testProperty: "d", id: 3},
 {testProperty: "b", id: 4}
];

expected = [
 {testProperty: "a", id: 2},
 {testProperty: "b", id: 4},
 {testProperty: "c", id: 1},
 {testProperty: "d", id: 3}
];

//act
input.sort(component.getComparisonFunction('testProperty'))

//assert
expect(input).toEqual(expected);

您也可以在更细化的级别添加更多的测试，以更加绑定的期望，如果你想。例如，如果你想确保比较是区分大小写

//arrange
a = { testProperty: "a" };
b = { testProperty: "B" };

//act
result = component.getComparisonFunction('testProperty')(a, b)

//assert
expect(result).toBeGreaterThanOrEqual(1)

或不区分大小写：

//arrange
a = { testProperty: "a" };
b = { testProperty: "B" };

//act
result = component.getComparisonFunction('testProperty')(a, b)

//assert
expect(result).toBeLessThanOrEqual(-1)

这更清楚地定义你的期望，并确保未来的变化将涵盖正是你需要的。

Answer 2:

如果你想通过任何PARAM提供实现排序，你可以尝试以下操作：

const array=[
  {name:'C',Key:'14',val:3},
  {name:'B',Key:'12',val:2},
  {name:'A',Key:'11',val:1},
  {name:'D',Key:'16',val:4},
  {name:'E',Key:'18',val:5}
];

console.log(array);

function comparer(prop){
  return function(a,b){
    return a[prop]-b[prop];
  }
};
array.sort(comparer('Key'));
console.log(array);
array.sort(comparer('val'));
console.log(array);

此外，为了测试它只需测试用例像上面，并检查其是否按照您的实现分拣。

文章来源: How to test two returned functions with different argument value in javascript?