feat: add object shorthand property mutator

packages/javascript-mutator/src/mutators/ObjectShorthandPropertyMutator.ts

@@ -0,0 +1,23 @@
+import * as types from '@babel/types';
+
+import { NodeGenerator } from '../helpers/NodeGenerator';
+
+import { NodeMutator } from './NodeMutator';
+
+/**
+ * Represents a mutator which can mutate an object shorthand property.
+ */
+export default class ObjectShorthandPropertyMutator implements NodeMutator {
+  public name = 'ObjectShorthandProperty';
+
+  public mutate(node: types.Node): Array<[types.Node, types.Node | { raw: string }]> {
+    return types.isObjectExpression(node)
+      ? node.properties
+          .filter((prop) => types.isObjectProperty(prop) && prop.shorthand)
+          .map((mutateProp) => [
+            node,
+            NodeGenerator.createMutatedCloneWithProperties(node, { properties: node.properties.filter((prop) => prop !== mutateProp) }),
+          ])
+      : [];
+  }
+}

packages/javascript-mutator/test/unit/mutators/ObjectShorthandPropertyMutator.spec.ts

@@ -0,0 +1,6 @@
+import { ObjectShorthandPropertyMutatorSpec } from '@stryker-mutator/mutator-specification/src/index';
+
+import ObjectShorthandPropertyMutator from '../../../src/mutators/ObjectShorthandPropertyMutator';
+import { verifySpecification } from '../../helpers/mutatorAssertions';
+
+verifySpecification(ObjectShorthandPropertyMutatorSpec, ObjectShorthandPropertyMutator);

packages/mutator-specification/src/ObjectShorthandPropertyMutatorSpec.ts

@@ -0,0 +1,27 @@
+import { expect } from 'chai';
+
+import ExpectMutation from './ExpectMutation';
+
+export default function ObjectShorthandPropertyMutatorSpec(name: string, expectMutation: ExpectMutation) {
+  describe('ObjectShorthandPropertyMutator', () => {
+    it('should have name "ObjectShorthandProperty"', () => {
+      expect(name).eq('ObjectShorthandProperty');
+    });
+
+    it('should mutate a single object shorthand property', () => {
+      expectMutation('const o = { bar }', 'const o = {}');
+    });
+
+    it('should mutate multiple object shorthand properties', () => {
+      expectMutation('const o = { bar, baz }', 'const o = { baz }', 'const o = { bar }');
+    });
+
+    it('should only mutate an object shorthand property', () => {
+      expectMutation('const o = { bar, baz: "qux" }', 'const o = { baz: "qux" }');
+    });
+
+    it('shoud not mutate empty object declarations', () => {
+      expectMutation('const o = {}');
+    });
+  });
+}

packages/mutator-specification/src/index.ts

@@ -7,6 +7,7 @@ export { default as ConditionalExpressionMutatorSpec } from './ConditionalExpres
 export { default as EqualityOperatorMutatorSpec } from './EqualityOperatorMutatorSpec';
 export { default as LogicalOperatorMutatorSpec } from './LogicalOperatorMutatorSpec';
 export { default as ObjectLiteralMutatorSpec } from './ObjectLiteralMutatorSpec';
+export { default as ObjectShorthandPropertyMutatorSpec } from './ObjectShorthandPropertyMutatorSpec';
 export { default as StringLiteralMutatorSpec } from './StringLiteralMutatorSpec';
 export { default as UnaryOperatorMutatorSpec } from './UnaryOperatorMutatorSpec';
 export { default as UpdateOperatorMutatorSpec } from './UpdateOperatorMutatorSpec';