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Enable use of assignment in the presence of accessors (#2538)
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fatso83 authored Oct 5, 2023
1 parent f8c20e5 commit cac5184
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1 change: 1 addition & 0 deletions .eslintignore
Original file line number Diff line number Diff line change
Expand Up @@ -8,6 +8,7 @@ docs/releases/
docs/_releases/
docs/assets/js/
docs/vendor
vendor/

# has linting of its own
docs/release-source/release/examples
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2 changes: 1 addition & 1 deletion docs/release-source/release.md
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Expand Up @@ -36,5 +36,5 @@ If you need to support old runtimes you can try [Sinon 9][compat-doc-v9].

{% include docs/contribute.md %}

[compat-doc]: https://github.com/sinonjs/sinon/COMPATIBILITY.md
[compat-doc]: https://github.com/sinonjs/sinon/blob/main/COMPATIBILITY.md
[compat-doc-v9]: https://github.com/sinonjs/sinon/blob/v9.2.4/COMPATIBILITY.md
16 changes: 12 additions & 4 deletions docs/release-source/release/sandbox.md
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Expand Up @@ -236,9 +236,17 @@ console.log(myObject.myMethod());
// strawberry
```

#### `sandbox.replaceGetter();`
#### `sandbox.replace.usingAccessor(object, property, value);`

Replaces getter for `property` on `object` with `replacement` argument. Attempts to replace an already replaced getter cause an exception.
Usually one intends to _replace_ the value or getter of a field, but there are use cases where one actually wants to _assign_ a value to a property using an existing setter. `#replace.usingAccessor(object, property, value)` will do just that; pass the value into setter function and vice-versa use the getter to get the value used for restoring later on.

##### Use case: no-frills dependency injection in ESM with cleanup

One use case can be to conveniently allow ESM module stubbing using pure dependency injection, having Sinon help you with the cleanup, without resorting to external machinery such as module loaders or require hooks (see [#2403](https://github.com/sinonjs/sinon/issues/2403)). This would then work regardless of bundler, browser or server environment.

#### `sandbox.replaceGetter(object, property, replacementFunction);`

Replaces an existing getter for `property` on `object` with the `replacementFunction` argument. Attempts to replace an already replaced getter cause an exception.

`replacement` must be a `Function`, and can be instances of `spies`, `stubs` and `fakes`.

Expand All @@ -257,9 +265,9 @@ console.log(myObject.myProperty);
// strawberry
```

#### `sandbox.replaceSetter();`
#### `sandbox.replaceSetter(object, property, replacementFunction);`

Replaces setter for `property` on `object` with `replacement` argument. Attempts to replace an already replaced setter cause an exception.
Replaces an existing setter for `property` on `object` with the `replacementFunction` argument. Attempts to replace an already replaced setter cause an exception.

`replacement` must be a `Function`, and can be instances of `spies`, `stubs` and `fakes`.

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104 changes: 73 additions & 31 deletions lib/sinon/sandbox.js
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Expand Up @@ -35,6 +35,40 @@ function applyOnEach(fakes, method) {
});
}

function throwOnAccessors(descriptor) {
if (typeof descriptor.get === "function") {
throw new Error("Use sandbox.replaceGetter for replacing getters");
}

if (typeof descriptor.set === "function") {
throw new Error("Use sandbox.replaceSetter for replacing setters");
}
}

function verifySameType(object, property, replacement) {
if (typeof object[property] !== typeof replacement) {
throw new TypeError(
`Cannot replace ${typeof object[
property
]} with ${typeof replacement}`
);
}
}

function checkForValidArguments(descriptor, property, replacement) {
if (typeof descriptor === "undefined") {
throw new TypeError(
`Cannot replace non-existent property ${valueToString(
property
)}. Perhaps you meant sandbox.define()?`
);
}

if (typeof replacement === "undefined") {
throw new TypeError("Expected replacement argument to be defined");
}
}

function Sandbox() {
const sandbox = this;
let fakeRestorers = [];
Expand Down Expand Up @@ -66,11 +100,6 @@ function Sandbox() {
return collection;
};

// this is for testing only
sandbox.getRestorers = function () {
return fakeRestorers;
};

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

Expand Down Expand Up @@ -196,11 +225,22 @@ function Sandbox() {
sandbox.injectedKeys.length = 0;
};

function getFakeRestorer(object, property) {
/**
* Creates a restorer function for the property
*
* @param {object|Function} object
* @param {string} property
* @param {boolean} forceAssignment
* @returns {Function} restorer function
*/
function getFakeRestorer(object, property, forceAssignment = false) {
const descriptor = getPropertyDescriptor(object, property);
const value = object[property];

function restorer() {
if (descriptor?.isOwn) {
if (forceAssignment) {
object[property] = value;
} else if (descriptor?.isOwn) {
Object.defineProperty(object, property, descriptor);
} else {
delete object[property];
Expand All @@ -225,41 +265,43 @@ function Sandbox() {
});
}

/**
* Replace an existing property
*
* @param {object|Function} object
* @param {string} property
* @param {*} replacement a fake, stub, spy or any other value
* @returns {*}
*/
sandbox.replace = function replace(object, property, replacement) {
const descriptor = getPropertyDescriptor(object, property);
checkForValidArguments(descriptor, property, replacement);
throwOnAccessors(descriptor);
verifySameType(object, property, replacement);

if (typeof descriptor === "undefined") {
throw new TypeError(
`Cannot replace non-existent property ${valueToString(
property
)}. Perhaps you meant sandbox.define()?`
);
}
verifyNotReplaced(object, property);

if (typeof replacement === "undefined") {
throw new TypeError("Expected replacement argument to be defined");
}
// store a function for restoring the replaced property
push(fakeRestorers, getFakeRestorer(object, property));

if (typeof descriptor.get === "function") {
throw new Error("Use sandbox.replaceGetter for replacing getters");
}
object[property] = replacement;

if (typeof descriptor.set === "function") {
throw new Error("Use sandbox.replaceSetter for replacing setters");
}
return replacement;
};

if (typeof object[property] !== typeof replacement) {
throw new TypeError(
`Cannot replace ${typeof object[
property
]} with ${typeof replacement}`
);
}
sandbox.replace.usingAccessor = function replaceUsingAccessor(
object,
property,
replacement
) {
const descriptor = getPropertyDescriptor(object, property);
checkForValidArguments(descriptor, property, replacement);
verifySameType(object, property, replacement);

verifyNotReplaced(object, property);

// store a function for restoring the replaced property
push(fakeRestorers, getFakeRestorer(object, property));
push(fakeRestorers, getFakeRestorer(object, property, true));

object[property] = replacement;

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2 changes: 1 addition & 1 deletion package.json
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Expand Up @@ -47,7 +47,7 @@
"dev-docs": "cd docs; cp -rl release-source releases/dev; npm run serve-docs",
"build-docs": "cd docs; bundle exec jekyll build",
"serve-docs": "cd docs; bundle exec jekyll serve --incremental --verbose --livereload",
"lint": "eslint --max-warnings 99 '**/*.{js,cjs,mjs}'",
"lint": "eslint --max-warnings 101 '**/*.{js,cjs,mjs}'",
"unimported": "unimported .",
"pretest-webworker": "npm run build",
"prebuild": "rimraf pkg && npm run check-dependencies",
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35 changes: 31 additions & 4 deletions test/sandbox-test.js
Original file line number Diff line number Diff line change
Expand Up @@ -398,6 +398,7 @@ describe("Sandbox", function () {
constructor() {
this.privateGetter = () => 42;
}

getValue() {
return this.privateGetter();
}
Expand Down Expand Up @@ -1072,8 +1073,8 @@ describe("Sandbox", function () {
assert.equals(actual, replacement);
});

describe("when asked to replace a getter", function () {
it("should throw an Error", function () {
describe("when asked to replace a property with a getter", function () {
it("should throw an Error by default that informs of replaceGetter", function () {
const sandbox = this.sandbox;
const object = {
get foo() {
Expand All @@ -1093,7 +1094,7 @@ describe("Sandbox", function () {
});
});

describe("when asked to replace a setter", function () {
describe("when asked to replace a property with a setter", function () {
it("should throw an Error", function () {
const sandbox = this.sandbox;
const object = {
Expand All @@ -1116,6 +1117,28 @@ describe("Sandbox", function () {
});
});

describe(".replace.usingAccessor", function () {
it("should allow using assignment when replacing a value", function () {
const sandbox = createSandbox();
let quaziPrivateStateOfObject = "original";
const object = {
// eslint-disable-next-line accessor-pairs
get foo() {
return quaziPrivateStateOfObject;
},
set foo(value) {
quaziPrivateStateOfObject = value;
},
};

assert.equals(object.foo, "original");
sandbox.replace.usingAccessor(object, "foo", "fake");
assert.equals(object.foo, "fake");
sandbox.restore();
assert.equals(object.foo, "original");
});
});

describe(".replaceGetter", function () {
beforeEach(function () {
this.sandbox = createSandbox();
Expand Down Expand Up @@ -1857,8 +1880,12 @@ describe("Sandbox", function () {
/* eslint-disable no-empty-function, accessor-pairs */
this.sandbox.inject(this.obj);

const myObj = { a: function () {} };
const myObj = {
a: function () {},
};

function MyClass() {}

MyClass.prototype.method1 = noop;
Object.defineProperty(myObj, "b", {
get: function () {
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