[英]How to mock a function inside another function (which I am testing) using sinon?
[英]Testing an inside function with sinon
我需要测试一个名为“缓存”的 function。 It is a function wrapper, which takes a function and caches its results depending on the arguments, that were applied to the function.
const cache = (func) => {
let cache = {};
let stringFromArgs;
return (...args) => {
let n = args[0];
if (stringFromArgs === JSON.stringify(args)) {
return cache[n];
} else {
stringFromArgs = JSON.stringify(args)
cache[n] = func(...args);
return cache[n];
}
}
}
这就是它的工作原理:
let complexFunction = function(arg1, arg2) {
return arg1 + arg2;
};
let cachedFunction = cache(complexFunction);
cachedFunction(1, 2); // complex function should be executed
cachedFunction(1, 2); // complex function should not be invoked again,
// instead the cached result should be returned
cachedFunction(1, 5); // should be executed, because the method wasn't invoked before with these arguments
当 function cachedFunction 使用相同的 arguments 调用两次时,function 内部的那个应该只调用一次。 第二次结果应该来自缓存。 我需要使用 sinon.js 进行测试。 或者也许有另一种方法来测试它?
这是单元测试解决方案:
cache.js
:
const cache = (func) => {
let cache = {};
let stringFromArgs;
return (...args) => {
let n = args[0];
if (stringFromArgs === JSON.stringify(args)) {
return cache[n];
} else {
stringFromArgs = JSON.stringify(args);
cache[n] = func(...args);
return cache[n];
}
};
};
module.exports = cache;
cache.test.js
:
const cache = require('./cache');
const sinon = require('sinon');
const { expect } = require('chai');
describe('62426207', () => {
it('should call complex function', () => {
let complexFunction = sinon.stub().callsFake((arg1, arg2) => {
return arg1 + arg2;
});
let cachedFunction = cache(complexFunction);
cachedFunction(1, 2);
sinon.assert.calledWith(complexFunction, 1, 2);
sinon.assert.calledOnce(complexFunction);
});
it('should not call complex function again', () => {
let complexFunction = sinon.stub().callsFake((arg1, arg2) => {
return arg1 + arg2;
});
let cachedFunction = cache(complexFunction);
cachedFunction(1, 2);
let ret = cachedFunction(1, 2);
expect(ret).to.be.equal(3);
sinon.assert.calledWith(complexFunction, 1, 2);
sinon.assert.calledOnce(complexFunction);
});
it('should call complex function if arguments are different', () => {
let complexFunction = sinon.stub().callsFake((arg1, arg2) => {
return arg1 + arg2;
});
let cachedFunction = cache(complexFunction);
let ret1 = cachedFunction(1, 2);
expect(ret1).to.be.equal(3);
let ret2 = cachedFunction(1, 5);
expect(ret2).to.be.equal(6);
sinon.assert.calledWith(complexFunction, 1, 2);
sinon.assert.calledWith(complexFunction, 1, 5);
sinon.assert.calledTwice(complexFunction);
});
});
覆盖率 100% 的单元测试结果:
62426207
✓ should call complex function
✓ should not call complex function again
✓ should call complex function if arguments are different
3 passing (18ms)
----------|---------|----------|---------|---------|-------------------
File | % Stmts | % Branch | % Funcs | % Lines | Uncovered Line #s
----------|---------|----------|---------|---------|-------------------
All files | 100 | 100 | 100 | 100 |
cache.js | 100 | 100 | 100 | 100 |
----------|---------|----------|---------|---------|-------------------
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