test_runner: add getter and setter to MockTracker

This commit allows tests in test runner to use the
`getter` and `setter` methods as "syntax sugar" for
`MockTracker.method` with the `options.getter` or
`options.setter` set to true in the options.

Refs: #45326 (comment)

doc/api/test.md

@@ -941,6 +941,17 @@ test('mocks a counting function', (t) => {
 });
 ```
 
+they are sorted in alphabetical order.
+
+### `mock.getter(object, methodName[, implementation][, options])`
+
+<!-- YAML
+added: REPLACEME
+-->
+
+This function is syntax sugar for [`MockTracker.method`][] with `options.getter`
+set to `true`.
+
 ### `mock.method(object, methodName[, implementation][, options])`
 
 <!-- YAML
@@ -1021,6 +1032,15 @@ This function restores the default behavior of all mocks that were previously
 created by this `MockTracker`. Unlike `mock.reset()`, `mock.restoreAll()` does
 not disassociate the mocks from the `MockTracker` instance.
 
+### `mock.setter(object, methodName[, implementation][, options])`
+
+<!-- YAML
+added: REPLACEME
+-->
+
+This function is syntax sugar for [`MockTracker.method`][] with `options.setter`
+set to `true`.
+
 ## Class: `TapStream`
 
 <!-- YAML
@@ -1357,6 +1377,7 @@ added:
 [`--test-only`]: cli.md#--test-only
 [`--test`]: cli.md#--test
 [`MockFunctionContext`]: #class-mockfunctioncontext
+[`MockTracker.method`]: #mockmethodobject-methodname-implementation-options
 [`MockTracker`]: #class-mocktracker
 [`SuiteContext`]: #class-suitecontext
 [`TestContext`]: #class-testcontext

lib/internal/test_runner/mock.js

@@ -202,6 +202,64 @@ class MockTracker {
     return mock;
   }
 
+  getter(
+    object,
+    methodName,
+    implementation = kDefaultFunction,
+    options = kEmptyObject
+  ) {
+    if (implementation !== null && typeof implementation === 'object') {
+      options = implementation;
+      implementation = kDefaultFunction;
+    }
+
+    validateObject(options, 'options');
+
+    const { getter = true } = options;
+
+    validateBoolean(getter, 'options.getter');
+
+    if (getter === false) {
+      throw new ERR_INVALID_ARG_VALUE(
+        'options.getter', getter, "cannot be 'false'"
+      );
+    }
+
+    return this.method(object, methodName, implementation, {
+      ...options,
+      getter: true
+    });
+  }
+
+  setter(
+    object,
+    methodName,
+    implementation = kDefaultFunction,
+    options = kEmptyObject
+  ) {
+    if (implementation !== null && typeof implementation === 'object') {
+      options = implementation;
+      implementation = kDefaultFunction;
+    }
+
+    validateObject(options, 'options');
+
+    const { setter = true } = options;
+
+    validateBoolean(setter, 'options.setter');
+
+    if (setter === false) {
+      throw new ERR_INVALID_ARG_VALUE(
+        'options.setter', setter, "cannot be 'false'"
+      );
+    }
+
+    return this.method(object, methodName, implementation, {
+      ...options,
+      setter: true
+    });
+  }
+
   reset() {
     this.restoreAll();
     this.#mocks = [];

test/parallel/test-runner-mocking.js

@@ -534,6 +534,69 @@ test('mocks a setter', (t) => {
   assert.strictEqual(obj.prop, 65);
 });
 
+test('mocks a getter with syntax sugar', (t) => {
+  const obj = {
+    prop: 5,
+    get method() {
+      return this.prop;
+    },
+  };
+
+  function mockMethod() {
+    return this.prop - 1;
+  }
+  const getter = t.mock.getter(obj, 'method', mockMethod);
+  assert.strictEqual(getter.mock.calls.length, 0);
+  assert.strictEqual(obj.method, 4);
+
+  const call = getter.mock.calls[0];
+
+  assert.deepStrictEqual(call.arguments, []);
+  assert.strictEqual(call.result, 4);
+  assert.strictEqual(call.target, undefined);
+  assert.strictEqual(call.this, obj);
+
+  assert.strictEqual(getter.mock.restore(), undefined);
+  assert.strictEqual(obj.method, 5);
+});
+
+test('mocks a setter with syntax sugar', (t) => {
+  const obj = {
+    prop: 100,
+    // eslint-disable-next-line accessor-pairs
+    set method(val) {
+      this.prop = val;
+    },
+  };
+
+  function mockMethod(val) {
+    this.prop = -val;
+  }
+
+  assert.strictEqual(obj.prop, 100);
+  obj.method = 88;
+  assert.strictEqual(obj.prop, 88);
+
+  const setter = t.mock.setter(obj, 'method', mockMethod);
+
+  assert.strictEqual(setter.mock.calls.length, 0);
+  obj.method = 77;
+  assert.strictEqual(obj.prop, -77);
+  assert.strictEqual(setter.mock.calls.length, 1);
+
+  const call = setter.mock.calls[0];
+
+  assert.deepStrictEqual(call.arguments, [77]);
+  assert.strictEqual(call.result, undefined);
+  assert.strictEqual(call.target, undefined);
+  assert.strictEqual(call.this, obj);
+
+  assert.strictEqual(setter.mock.restore(), undefined);
+  assert.strictEqual(obj.prop, -77);
+  obj.method = 65;
+  assert.strictEqual(obj.prop, 65);
+});
+
 test('mocked functions match name and length', (t) => {
   function getNameAndLength(fn) {
     return {
@@ -799,3 +862,27 @@ test('spies on a class prototype method', (t) => {
   assert.strictEqual(call.target, undefined);
   assert.strictEqual(call.this, instance);
 });
+
+test('getter() fails if getter options set to false', (t) => {
+  assert.throws(() => {
+    t.mock.getter({}, 'method', { getter: false });
+  }, /The property 'options\.getter' cannot be 'false'/);
+});
+
+test('setter() fails if setter options set to false', (t) => {
+  assert.throws(() => {
+    t.mock.setter({}, 'method', { setter: false });
+  }, /The property 'options\.setter' cannot be 'false'/);
+});
+
+test('getter() fails if setter options is true', (t) => {
+  assert.throws(() => {
+    t.mock.getter({}, 'method', { setter: true });
+  }, /The property 'options\.setter' cannot be used with 'options\.getter'/);
+});
+
+test('setter() fails if getter options is true', (t) => {
+  assert.throws(() => {
+    t.mock.setter({}, 'method', { getter: true });
+  }, /The property 'options\.setter' cannot be used with 'options\.getter'/);
+});