使用chai-chai和sinon测试浮点逻辑

Question

我有一个测试用例失败了，因为被测试的值被Number.EPSILON关闭了。我理解为什么会发生这种情况，并相信我需要修改我的测试用例，以便它能够容忍这种差异。我相信使用chai-almost来帮助实现这一点是有意义的，但我正在努力弄清楚如何将chai-almost与sinon-chai集成在一起，并且正在寻找想法。

具体来说，我使用的是sinon-chai提供的calledWithMatch方法。calledWithMatch方法在两个对象之间执行深度相等检查，并且不考虑引用相等性。我想放宽这个方法来容忍Number.EPSILON的差异。

下面的代码片段突出显示了一个失败的测试用例的问题。测试用例失败是因为persist调用了一个边界框，由于top被Number.EPSILON关闭，这个边界框没有达到我们的预期。在这种情况下，测试用例应该通过，因为数据没有任何错误。

​

mocha.setup('bdd');

const updater = {
  updateBoundingBox(boundingBox) {
    const newBoundingBox = { ...boundingBox };
    newBoundingBox.top -= .2;
    newBoundingBox.top += .2;  
    this.persist(newBoundingBox);
  },
  
  persist(boundingBox) {
    console.log('persisting bounding box', boundingBox);
  }
};

describe('example', () => {
  it('should pass', () => {
    const persistSpy = sinon.spy(updater, 'persist');

    const originalBoundingBox = {
      top: 0.01,
      left: 0.01,
      bottom: 0.01,
      right: 0.01,
    };
    updater.updateBoundingBox(originalBoundingBox);
    chai.expect(persistSpy).calledWithMatch(originalBoundingBox);
  });
});

mocha.run();

<script src="https://cdnjs.cloudflare.com/ajax/libs/mocha/6.1.4/mocha.min.js"></script>
<script src="https://cdnjs.cloudflare.com/ajax/libs/chai/4.2.0/chai.min.js"></script>
<script src="https://cdnjs.cloudflare.com/ajax/libs/sinon.js/7.3.2/sinon.min.js"></script>
<script>
"use strict";
/* eslint-disable no-invalid-this */

(function (sinonChai) {
    // Module systems magic dance.

    /* istanbul ignore else */
    if (typeof require === "function" && typeof exports === "object" && typeof module === "object") {
        // NodeJS
        module.exports = sinonChai;
    } else if (typeof define === "function" && define.amd) {
        // AMD
        define(function () {
            return sinonChai;
        });
    } else {
        // Other environment (usually <script> tag): plug in to global chai instance directly.
        /* global chai: false */
        chai.use(sinonChai);
    }
}(function (chai, utils) {
    var slice = Array.prototype.slice;

    function isSpy(putativeSpy) {
        return typeof putativeSpy === "function" &&
               typeof putativeSpy.getCall === "function" &&
               typeof putativeSpy.calledWithExactly === "function";
    }

    function timesInWords(count) {
        switch (count) {
            case 1: {
                return "once";
            }
            case 2: {
                return "twice";
            }
            case 3: {
                return "thrice";
            }
            default: {
                return (count || 0) + " times";
            }
        }
    }

    function isCall(putativeCall) {
        return putativeCall && isSpy(putativeCall.proxy);
    }

    function assertCanWorkWith(assertion) {
        if (!isSpy(assertion._obj) && !isCall(assertion._obj)) {
            throw new TypeError(utils.inspect(assertion._obj) + " is not a spy or a call to a spy!");
        }
    }

    function getMessages(spy, action, nonNegatedSuffix, always, args) {
        var verbPhrase = always ? "always have " : "have ";
        nonNegatedSuffix = nonNegatedSuffix || "";
        if (isSpy(spy.proxy)) {
            spy = spy.proxy;
        }

        function printfArray(array) {
            return spy.printf.apply(spy, array);
        }

        return {
            affirmative: function () {
                return printfArray(["expected %n to " + verbPhrase + action + nonNegatedSuffix].concat(args));
            },
            negative: function () {
                return printfArray(["expected %n to not " + verbPhrase + action].concat(args));
            }
        };
    }

    function sinonProperty(name, action, nonNegatedSuffix) {
        utils.addProperty(chai.Assertion.prototype, name, function () {
            assertCanWorkWith(this);

            var messages = getMessages(this._obj, action, nonNegatedSuffix, false);
            this.assert(this._obj[name], messages.affirmative, messages.negative);
        });
    }

    function sinonPropertyAsBooleanMethod(name, action, nonNegatedSuffix) {
        utils.addMethod(chai.Assertion.prototype, name, function (arg) {
            assertCanWorkWith(this);

            var messages = getMessages(this._obj, action, nonNegatedSuffix, false, [timesInWords(arg)]);
            this.assert(this._obj[name] === arg, messages.affirmative, messages.negative);
        });
    }

    function createSinonMethodHandler(sinonName, action, nonNegatedSuffix) {
        return function () {
            assertCanWorkWith(this);

            var alwaysSinonMethod = "always" + sinonName[0].toUpperCase() + sinonName.substring(1);
            var shouldBeAlways = utils.flag(this, "always") && typeof this._obj[alwaysSinonMethod] === "function";
            var sinonMethodName = shouldBeAlways ? alwaysSinonMethod : sinonName;

            var messages = getMessages(this._obj, action, nonNegatedSuffix, shouldBeAlways, slice.call(arguments));
            this.assert(
                this._obj[sinonMethodName].apply(this._obj, arguments),
                messages.affirmative,
                messages.negative
            );
        };
    }

    function sinonMethodAsProperty(name, action, nonNegatedSuffix) {
        var handler = createSinonMethodHandler(name, action, nonNegatedSuffix);
        utils.addProperty(chai.Assertion.prototype, name, handler);
    }

    function exceptionalSinonMethod(chaiName, sinonName, action, nonNegatedSuffix) {
        var handler = createSinonMethodHandler(sinonName, action, nonNegatedSuffix);
        utils.addMethod(chai.Assertion.prototype, chaiName, handler);
    }

    function sinonMethod(name, action, nonNegatedSuffix) {
        exceptionalSinonMethod(name, name, action, nonNegatedSuffix);
    }

    utils.addProperty(chai.Assertion.prototype, "always", function () {
        utils.flag(this, "always", true);
    });

    sinonProperty("called", "been called", " at least once, but it was never called");
    sinonPropertyAsBooleanMethod("callCount", "been called exactly %1", ", but it was called %c%C");
    sinonProperty("calledOnce", "been called exactly once", ", but it was called %c%C");
    sinonProperty("calledTwice", "been called exactly twice", ", but it was called %c%C");
    sinonProperty("calledThrice", "been called exactly thrice", ", but it was called %c%C");
    sinonMethodAsProperty("calledWithNew", "been called with new");
    sinonMethod("calledBefore", "been called before %1");
    sinonMethod("calledAfter", "been called after %1");
    sinonMethod("calledImmediatelyBefore", "been called immediately before %1");
    sinonMethod("calledImmediatelyAfter", "been called immediately after %1");
    sinonMethod("calledOn", "been called with %1 as this", ", but it was called with %t instead");
    sinonMethod("calledWith", "been called with arguments %*", "%D");
    sinonMethod("calledOnceWith", "been called exactly once with arguments %*", "%D");
    sinonMethod("calledWithExactly", "been called with exact arguments %*", "%D");
    sinonMethod("calledOnceWithExactly", "been called exactly once with exact arguments %*", "%D");
    sinonMethod("calledWithMatch", "been called with arguments matching %*", "%D");
    sinonMethod("returned", "returned %1");
    exceptionalSinonMethod("thrown", "threw", "thrown %1");
}));
</script>

<div id="mocha"></div>

​

我真的不确定下一步该怎么做。如果我直接使用这两个实体，而不是使用calledWithMatch，我将使用chai-almost显式地检查top、bottom、left和right的值。类似于：

expect(newBoundingBox.top).to.almost.equal(boundingBox.top)
expect(newBoundingBox.bottom).to.almost.equal(boundingBox.bottom)
expect(newBoundingBox.left).to.almost.equal(boundingBox.left)
expect(newBoundingBox.right).to.almost.equal(boundingBox.right)

但在使用calledWithMatch时，我看不到一种方法来实现这一点。

我是不是遗漏了什么？有没有简单的方法来解决这个问题呢？

编辑:在我修补的时候更新这个。

我认为正确的方法可能是使用自定义匹配器，但我还没有可用的代码：https://sinonjs.org/releases/latest/matchers/#custom-matchers

看起来calledWithMatch(foo)的功能等价物是calledWith(sinon.match(foo))，这使得如何引入自定义匹配器的用法变得更加清晰。

Answer 1

好吧，我想通了。

诀窍是将sinon-chai方法calledWithMatch替换为其较低级别的实现calledWith(sinon.match。这允许用户定义一个自定义的匹配器。我展示了我在下面的例子中使用的那个。

​

mocha.setup('bdd');

const updater = {
  updateBoundingBox(boundingBox) {
    const newBoundingBox = { ...boundingBox };
    newBoundingBox.top -= .2;
    newBoundingBox.top += .2;  
    this.persist(newBoundingBox);
  },
  
  persist(boundingBox) {
    console.log('persisting bounding box', boundingBox);
  }
};

describe('example', () => {
  it('should pass', () => {
    const persistSpy = sinon.spy(updater, 'persist');

    const originalBoundingBox = {
      top: 0.01,
      left: 0.01,
      bottom: 0.01,
      right: 0.01,
    };
    updater.updateBoundingBox(originalBoundingBox);
    chai.expect(persistSpy).calledWith(sinon.match((boundingBox) => {
        if (!boundingBox) return false;
        
        const isLeftEqual = Math.abs(originalBoundingBox.left - boundingBox.left) < Number.EPSILON;
        const isRightEqual = Math.abs(originalBoundingBox.right - boundingBox.right) < Number.EPSILON;
        const isTopEqual = Math.abs(originalBoundingBox.top - boundingBox.top) < Number.EPSILON;
        const isBottomEqual = Math.abs(originalBoundingBox.bottom - boundingBox.bottom) < Number.EPSILON;
        
        return isLeftEqual && isRightEqual && isTopEqual && isBottomEqual; 
    }));
  });
});

mocha.run();

<script src="https://cdnjs.cloudflare.com/ajax/libs/mocha/6.1.4/mocha.min.js"></script>
<script src="https://cdnjs.cloudflare.com/ajax/libs/chai/4.2.0/chai.min.js"></script>
<script src="https://cdnjs.cloudflare.com/ajax/libs/sinon.js/7.3.2/sinon.min.js"></script>
<script>
"use strict";
/* eslint-disable no-invalid-this */

(function (sinonChai) {
    // Module systems magic dance.

    /* istanbul ignore else */
    if (typeof require === "function" && typeof exports === "object" && typeof module === "object") {
        // NodeJS
        module.exports = sinonChai;
    } else if (typeof define === "function" && define.amd) {
        // AMD
        define(function () {
            return sinonChai;
        });
    } else {
        // Other environment (usually <script> tag): plug in to global chai instance directly.
        /* global chai: false */
        chai.use(sinonChai);
    }
}(function (chai, utils) {
    var slice = Array.prototype.slice;

    function isSpy(putativeSpy) {
        return typeof putativeSpy === "function" &&
               typeof putativeSpy.getCall === "function" &&
               typeof putativeSpy.calledWithExactly === "function";
    }

    function timesInWords(count) {
        switch (count) {
            case 1: {
                return "once";
            }
            case 2: {
                return "twice";
            }
            case 3: {
                return "thrice";
            }
            default: {
                return (count || 0) + " times";
            }
        }
    }

    function isCall(putativeCall) {
        return putativeCall && isSpy(putativeCall.proxy);
    }

    function assertCanWorkWith(assertion) {
        if (!isSpy(assertion._obj) && !isCall(assertion._obj)) {
            throw new TypeError(utils.inspect(assertion._obj) + " is not a spy or a call to a spy!");
        }
    }

    function getMessages(spy, action, nonNegatedSuffix, always, args) {
        var verbPhrase = always ? "always have " : "have ";
        nonNegatedSuffix = nonNegatedSuffix || "";
        if (isSpy(spy.proxy)) {
            spy = spy.proxy;
        }

        function printfArray(array) {
            return spy.printf.apply(spy, array);
        }

        return {
            affirmative: function () {
                return printfArray(["expected %n to " + verbPhrase + action + nonNegatedSuffix].concat(args));
            },
            negative: function () {
                return printfArray(["expected %n to not " + verbPhrase + action].concat(args));
            }
        };
    }

    function sinonProperty(name, action, nonNegatedSuffix) {
        utils.addProperty(chai.Assertion.prototype, name, function () {
            assertCanWorkWith(this);

            var messages = getMessages(this._obj, action, nonNegatedSuffix, false);
            this.assert(this._obj[name], messages.affirmative, messages.negative);
        });
    }

    function sinonPropertyAsBooleanMethod(name, action, nonNegatedSuffix) {
        utils.addMethod(chai.Assertion.prototype, name, function (arg) {
            assertCanWorkWith(this);

            var messages = getMessages(this._obj, action, nonNegatedSuffix, false, [timesInWords(arg)]);
            this.assert(this._obj[name] === arg, messages.affirmative, messages.negative);
        });
    }

    function createSinonMethodHandler(sinonName, action, nonNegatedSuffix) {
        return function () {
            assertCanWorkWith(this);

            var alwaysSinonMethod = "always" + sinonName[0].toUpperCase() + sinonName.substring(1);
            var shouldBeAlways = utils.flag(this, "always") && typeof this._obj[alwaysSinonMethod] === "function";
            var sinonMethodName = shouldBeAlways ? alwaysSinonMethod : sinonName;

            var messages = getMessages(this._obj, action, nonNegatedSuffix, shouldBeAlways, slice.call(arguments));
            this.assert(
                this._obj[sinonMethodName].apply(this._obj, arguments),
                messages.affirmative,
                messages.negative
            );
        };
    }

    function sinonMethodAsProperty(name, action, nonNegatedSuffix) {
        var handler = createSinonMethodHandler(name, action, nonNegatedSuffix);
        utils.addProperty(chai.Assertion.prototype, name, handler);
    }

    function exceptionalSinonMethod(chaiName, sinonName, action, nonNegatedSuffix) {
        var handler = createSinonMethodHandler(sinonName, action, nonNegatedSuffix);
        utils.addMethod(chai.Assertion.prototype, chaiName, handler);
    }

    function sinonMethod(name, action, nonNegatedSuffix) {
        exceptionalSinonMethod(name, name, action, nonNegatedSuffix);
    }

    utils.addProperty(chai.Assertion.prototype, "always", function () {
        utils.flag(this, "always", true);
    });

    sinonProperty("called", "been called", " at least once, but it was never called");
    sinonPropertyAsBooleanMethod("callCount", "been called exactly %1", ", but it was called %c%C");
    sinonProperty("calledOnce", "been called exactly once", ", but it was called %c%C");
    sinonProperty("calledTwice", "been called exactly twice", ", but it was called %c%C");
    sinonProperty("calledThrice", "been called exactly thrice", ", but it was called %c%C");
    sinonMethodAsProperty("calledWithNew", "been called with new");
    sinonMethod("calledBefore", "been called before %1");
    sinonMethod("calledAfter", "been called after %1");
    sinonMethod("calledImmediatelyBefore", "been called immediately before %1");
    sinonMethod("calledImmediatelyAfter", "been called immediately after %1");
    sinonMethod("calledOn", "been called with %1 as this", ", but it was called with %t instead");
    sinonMethod("calledWith", "been called with arguments %*", "%D");
    sinonMethod("calledOnceWith", "been called exactly once with arguments %*", "%D");
    sinonMethod("calledWithExactly", "been called with exact arguments %*", "%D");
    sinonMethod("calledOnceWithExactly", "been called exactly once with exact arguments %*", "%D");
    sinonMethod("calledWithMatch", "been called with arguments matching %*", "%D");
    sinonMethod("returned", "returned %1");
    exceptionalSinonMethod("thrown", "threw", "thrown %1");
}));
</script>

<div id="mocha"></div>

​