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fix: make it possible to call through to underlying stub in stub inst…
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…ance (#2503)

* fix: make it possible to call through to underlying stub in stub instances

refs #2477
refs #2501

* internal: Extract underlying createStubInstance

* internal: extract tests into own module

* internal: extract sinon type checking into own module

closes #2501
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fatso83 authored Mar 26, 2023
1 parent 6e19746 commit 477064b
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Showing 8 changed files with 246 additions and 182 deletions.
36 changes: 36 additions & 0 deletions lib/sinon/create-stub-instance.js
Original file line number Diff line number Diff line change
@@ -0,0 +1,36 @@
"use strict";

const stub = require("./stub");
const sinonType = require("./util/core/sinon-type");
const forEach = require("@sinonjs/commons").prototypes.array.forEach;

function isStub(value) {
return sinonType.get(value) === "stub";
}

module.exports = function createStubInstance(constructor, overrides) {
if (typeof constructor !== "function") {
throw new TypeError("The constructor should be a function.");
}

const stubInstance = Object.create(constructor.prototype);
sinonType.set(stubInstance, "stub-instance");

const stubbedObject = stub(stubInstance);

forEach(Object.keys(overrides || {}), function (propertyName) {
if (propertyName in stubbedObject) {
var value = overrides[propertyName];
if (isStub(value)) {
stubbedObject[propertyName] = value;
} else {
stubbedObject[propertyName].returns(value);
}
} else {
throw new Error(
`Cannot stub ${propertyName}. Property does not exist!`
);
}
});
return stubbedObject;
};
3 changes: 2 additions & 1 deletion lib/sinon/sandbox.js
Original file line number Diff line number Diff line change
Expand Up @@ -11,6 +11,7 @@ var sinonClock = require("./util/fake-timers");
var sinonMock = require("./mock");
var sinonSpy = require("./spy");
var sinonStub = require("./stub");
var sinonCreateStubInstance = require("./create-stub-instance");
var sinonFake = require("./fake");
var valueToString = require("@sinonjs/commons").valueToString;
var fakeServer = require("nise").fakeServer;
Expand Down Expand Up @@ -71,7 +72,7 @@ function Sandbox() {
};

sandbox.createStubInstance = function createStubInstance() {
var stubbed = sinonStub.createStubInstance.apply(null, arguments);
var stubbed = sinonCreateStubInstance.apply(null, arguments);

var ownMethods = collectOwnMethods(stubbed);

Expand Down
32 changes: 3 additions & 29 deletions lib/sinon/stub.js
Original file line number Diff line number Diff line change
Expand Up @@ -12,6 +12,7 @@ var spy = require("./spy");
var extend = require("./util/core/extend");
var getPropertyDescriptor = require("./util/core/get-property-descriptor");
var isEsModule = require("./util/core/is-es-module");
var sinonType = require("./util/core/sinon-type");
var wrapMethod = require("./util/core/wrap-method");
var throwOnFalsyObject = require("./throw-on-falsy-object");
var valueToString = require("@sinonjs/commons").valueToString;
Expand Down Expand Up @@ -58,6 +59,8 @@ function createStub(originalFunc) {
id: `stub#${uuid++}`,
});

sinonType.set(proxy, "stub");

return proxy;
}

Expand Down Expand Up @@ -126,35 +129,6 @@ function stub(object, property) {
return isStubbingNonFuncProperty ? s : wrapMethod(object, property, s);
}

stub.createStubInstance = function (constructor, overrides) {
if (typeof constructor !== "function") {
throw new TypeError("The constructor should be a function.");
}

// eslint-disable-next-line no-empty-function
const noop = () => {};
const defaultNoOpInstance = Object.create(constructor.prototype);
walkObject((obj, prop) => (obj[prop] = noop), defaultNoOpInstance);

const stubbedObject = stub(defaultNoOpInstance);

forEach(Object.keys(overrides || {}), function (propertyName) {
if (propertyName in stubbedObject) {
var value = overrides[propertyName];
if (value && value.createStubInstance) {
stubbedObject[propertyName] = value;
} else {
stubbedObject[propertyName].returns(value);
}
} else {
throw new Error(
`Cannot stub ${propertyName}. Property does not exist!`
);
}
});
return stubbedObject;
};

function assertValidPropertyDescriptor(descriptor, property) {
if (!descriptor || !property) {
return;
Expand Down
22 changes: 22 additions & 0 deletions lib/sinon/util/core/sinon-type.js
Original file line number Diff line number Diff line change
@@ -0,0 +1,22 @@
"use strict";

const sinonTypeSymbolProperty = Symbol("SinonType");

module.exports = {
/**
* Set the type of a Sinon object to make it possible to identify it later at runtime
*
* @param {object|Function} object object/function to set the type on
* @param {string} type the named type of the object/function
*/
set(object, type) {
Object.defineProperty(object, sinonTypeSymbolProperty, {
value: type,
configurable: false,
enumerable: false,
});
},
get(object) {
return object && object[sinonTypeSymbolProperty];
},
};
8 changes: 8 additions & 0 deletions lib/sinon/util/core/wrap-method.js
Original file line number Diff line number Diff line change
@@ -1,7 +1,10 @@
"use strict";

// eslint-disable-next-line no-empty-function
const noop = () => {};
var getPropertyDescriptor = require("./get-property-descriptor");
var extend = require("./extend");
const sinonType = require("./sinon-type");
var hasOwnProperty =
require("@sinonjs/commons").prototypes.object.hasOwnProperty;
var valueToString = require("@sinonjs/commons").valueToString;
Expand Down Expand Up @@ -230,6 +233,11 @@ module.exports = function wrapMethod(object, property, method) {
}
}
}
if (sinonType.get(object) === "stub-instance") {
// this is simply to avoid errors after restoring if something should
// traverse the object in a cleanup phase, ref #2477
object[property] = noop;
}
}

return method;
Expand Down
158 changes: 158 additions & 0 deletions test/create-stub-instance-test.js
Original file line number Diff line number Diff line change
@@ -0,0 +1,158 @@
"use strict";

var referee = require("@sinonjs/referee");
var createStub = require("../lib/sinon/stub");
var createStubInstance = require("../lib/sinon/create-stub-instance");
var assert = referee.assert;
var refute = referee.refute;

describe("createStubInstance", function () {
it("stubs existing methods", function () {
var Class = function () {
return;
};
Class.prototype.method = function () {
return;
};

var stub = createStubInstance(Class);
stub.method.returns(3);
assert.equals(3, stub.method());
});

it("throws with no methods to stub", function () {
var Class = function () {
return;
};

assert.exception(
function () {
createStubInstance(Class);
},
{
message:
"Found no methods on object to which we could apply mutations",
}
);
});

it("doesn't call the constructor", function () {
var Class = function (a, b) {
var c = a + b;
throw c;
};
Class.prototype.method = function () {
return;
};

var stub = createStubInstance(Class);
refute.exception(function () {
stub.method(3);
});
});

it("retains non function values", function () {
var TYPE = "some-value";
var Class = function () {
return;
};
Class.prototype.method = function () {
return;
};
Class.prototype.type = TYPE;

var stub = createStubInstance(Class);
assert.equals(TYPE, stub.type);
});

it("has no side effects on the prototype", function () {
var proto = {
method: function () {
throw new Error("error");
},
};
var Class = function () {
return;
};
Class.prototype = proto;

var stub = createStubInstance(Class);
refute.exception(stub.method);
assert.exception(proto.method);
});

it("throws exception for non function params", function () {
var types = [{}, 3, "hi!"];

for (var i = 0; i < types.length; i++) {
// yes, it's silly to create functions in a loop, it's also a test
// eslint-disable-next-line no-loop-func
assert.exception(function () {
createStubInstance(types[i]);
});
}
});

it("allows providing optional overrides", function () {
var Class = function () {
return;
};
Class.prototype.method = function () {
return;
};

var stub = createStubInstance(Class, {
method: createStub().returns(3),
});

assert.equals(3, stub.method());
});

it("allows providing optional returned values", function () {
var Class = function () {
return;
};
Class.prototype.method = function () {
return;
};

var stub = createStubInstance(Class, {
method: 3,
});

assert.equals(3, stub.method());
});

it("allows providing null as a return value", function () {
var Class = function () {
return;
};
Class.prototype.method = function () {
return;
};

var stub = createStubInstance(Class, {
method: null,
});

assert.equals(null, stub.method());
});

it("throws an exception when trying to override non-existing property", function () {
var Class = function () {
return;
};
Class.prototype.method = function () {
return;
};

assert.exception(
function () {
createStubInstance(Class, {
foo: createStub().returns(3),
});
},
{ message: "Cannot stub foo. Property does not exist!" }
);
});
});
17 changes: 17 additions & 0 deletions test/issues/issues-test.js
Original file line number Diff line number Diff line change
Expand Up @@ -805,4 +805,21 @@ describe("issues", function () {
assert.isUndefined(restoredPropertyDescriptor);
});
});

describe("#2501 - createStubInstance stubs are not able to call through to the underlying function on the prototype", function () {
it("should be able call through to the underlying function on the prototype", function () {
class Foo {
testMethod() {
this.wasCalled = true;
return 42;
}
}

const fooStubInstance = this.sandbox.createStubInstance(Foo);
fooStubInstance.testMethod.callThrough();
// const fooStubInstance = new Foo()
fooStubInstance.testMethod();
// assert.isTrue(fooStubInstance.wasCalled);
});
});
});
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