feat(JavaScript mutator): Add stryker-javascript-mutator package (#467)

* Add stryker-javascript-mutator package that is compatible with modern JavaScript features such as arrow functions.
* Deprecate the `ES5Mutator`
* Remove `UnaryNotMutator` as it is already present in the `PrefixUnaryExpressionMutator`
* Make the `ConditionalExpressionMutator` also mutate to `true`

Fixes #429

package.json

@@ -1,6 +1,7 @@
 {
   "private": true,
   "devDependencies": {
+    "@types/babel-core": "^6.25.2",
     "@types/chai-as-promised": "0.0.31",
     "@types/chalk": "^0.4.28",
     "@types/commander": "^2.9.0",

packages/stryker-javascript-mutator/.npmignore

@@ -0,0 +1,10 @@
+**/*
+!*.d.ts
+!bin/**
+!src/**
+src/**/*.map
+src/**/*.ts
+!src/**/*.d.ts
+!readme.md
+!LICENSE
+!CHANGELOG.md

packages/stryker-javascript-mutator/.vscode/launch.json

@@ -0,0 +1,36 @@
+{
+  "version": "0.2.0",
+  "configurations": [
+    {
+      "type": "node",
+      "request": "launch",
+      "name": "Unit tests",
+      "program": "${workspaceRoot}/../../node_modules/mocha/bin/_mocha",
+      "args": [
+        "-u",
+        "tdd",
+        "--timeout",
+        "999999",
+        "--colors",
+        "${workspaceRoot}/test/helpers/**/*.js",
+        "${workspaceRoot}/test/unit/**/*.js"
+      ],
+      "internalConsoleOptions": "openOnSessionStart"
+    }, {
+      "type": "node",
+      "request": "launch",
+      "name": "Integration tests",
+      "program": "${workspaceRoot}/../../node_modules/mocha/bin/_mocha",
+      "args": [
+        "-u",
+        "tdd",
+        "--timeout",
+        "999999",
+        "--colors",
+        "${workspaceRoot}/test/helpers/**/*.js",
+        "${workspaceRoot}/test/integration/**/*.js"
+      ],
+      "internalConsoleOptions": "openOnSessionStart"
+    }
+  ]
+}

packages/stryker-javascript-mutator/.vscode/settings.json

@@ -0,0 +1,14 @@
+{
+  "typescript.tsdk": "../../node_modules/typescript/lib",
+  "files.exclude": {
+      ".git": true,
+      ".tscache": true,
+      "**/*.js": {
+        "when": "$(basename).ts"
+      },
+      "**/*.d.ts": true,
+      "**/*.map": {
+        "when": "$(basename)"
+      }
+  }
+}

packages/stryker-javascript-mutator/.vscode/tasks.json

@@ -0,0 +1,18 @@
+{
+  // See https://go.microsoft.com/fwlink/?LinkId=733558
+  // for the documentation about the tasks.json format
+  "version": "2.0.0",
+  "tasks": [
+      {
+          "taskName": "tsc-watch",
+          "type": "shell",
+          "command": "npm start",
+          "problemMatcher": "$tsc-watch",
+          "isBackground": true,
+          "group": {
+              "kind": "build",
+              "isDefault": true
+          }
+      }
+  ]
+}

packages/stryker-javascript-mutator/README.md

@@ -0,0 +1,39 @@
+[![Build Status](https://travis-ci.org/stryker-mutator/stryker.svg?branch=master)](https://travis-ci.org/stryker-mutator/stryker)
+[![NPM](https://img.shields.io/npm/dm/stryker-javascript-mutator.svg)](https://www.npmjs.com/package/stryker-javascript-mutator)
+[![Node version](https://img.shields.io/node/v/stryker-javascript-mutator.svg)](https://img.shields.io/node/v/stryker-javascript-mutator.svg)
+[![Gitter](https://badges.gitter.im/stryker-mutator/stryker.svg)](https://gitter.im/stryker-mutator/stryker?utm_source=badge&utm_medium=badge&utm_campaign=pr-badge)
+[![BCH compliance](https://bettercodehub.com/edge/badge/stryker-mutator/stryker)](https://bettercodehub.com/)
+
+![Stryker](https://github.com/stryker-mutator/stryker/raw/master/stryker-80x80.png)
+
+# Stryker JavaScript mutator
+
+A mutator that supports JavaScript for [Stryker](https://stryker-mutator.github.io), the JavaScript Mutation testing framework. This plugin does not transpile any code. The code that the stryker-javascript-mutator gets should be executable in your environment (i.e. the stryker-javascript-mutator does not add support for Babel projects). 
+
+## Quickstart
+
+First, install Stryker itself (you can follow the [quickstart on the website](http://stryker-mutator.github.io/quickstart.html))
+
+Next, install this package:
+
+```bash
+npm install --save-dev stryker-javascript-mutator
+```
+
+Now open up your stryker.conf.js file and add the following components:
+
+```javascript
+mutator: 'javascript',
+```
+
+Now give it a go:
+
+```bash
+$ stryker run
+```
+
+### JavaScript Mutator
+
+The `JavaScript Mutator` is a plugin to mutate JavaScript code. This is done using Babel without any plugins.
+
+See [test code](https://github.com/stryker-mutator/stryker/tree/master/packages/stryker-javascript-mutator/test/unit/mutator) to know which mutations are supported.

packages/stryker-javascript-mutator/package.json

@@ -0,0 +1,56 @@
+{
+  "name": "stryker-javascript-mutator",
+  "version": "0.1.0",
+  "description": "A plugin for javascript projects using Stryker",
+  "main": "src/index.js",
+  "scripts": {
+    "start": "tsc -w",
+    "clean": "rimraf \"+(test|src)/**/*+(.d.ts|.js|.map)\" reports",
+    "prebuild": "npm run clean",
+    "build": "tsc -p .",
+    "postbuild": "tslint -p tsconfig.json",
+    "test": "nyc --reporter=html --report-dir=reports/coverage --check-coverage --lines 85 --functions 90 --branches 60 mocha \"test/helpers/**/*.js\" \"test/unit/**/*.js\" "
+  },
+  "repository": {
+    "type": "git",
+    "url": "https://github.com/stryker-mutator/stryker"
+  },
+  "engines": {
+    "node": ">=4"
+  },
+  "keywords": [
+    "stryker",
+    "stryker-plugin",
+    "javascript",
+    "stryker-mutator"
+  ],
+  "bugs": {
+    "url": "https://github.com/stryker-mutator/stryker/issues"
+  },
+  "author": "Simon de Lang <[email protected]>",
+  "contributors": [
+    "Nico Jansen <[email protected]>",
+    "Niek te Grootenhuis <[email protected]>",
+    "Thomas Peters <[email protected]>",
+    "Sander Koenders <[email protected]>"
+  ],
+  "homepage": "https://github.com/stryker-mutator/stryker/tree/master/packages/stryker-javascript-mutator#readme",
+  "license": "Apache-2.0",
+  "dependencies": {
+    "babel-core": "^6.26.0",
+    "babel-generator": "^6.26.0",
+    "babylon": "^6.18.0",
+    "log4js": "^1.1.1",
+    "tslib": "^1.8.0"
+  },
+  "devDependencies": {
+    "@types/babel-generator": "^6.25.1",
+    "@types/babylon": "^6.16.2",
+    "stryker-api": "^0.11.0",
+    "stryker-mutator-specification": "^0.1.0"
+  },
+  "peerDependencies": {
+    "stryker-api": "^0.11.0",
+    "typescript": "^2.5.3"
+  }
+}

packages/stryker-javascript-mutator/src/JavaScriptMutator.ts

@@ -0,0 +1,65 @@
+import * as babel from 'babel-core';
+import { getLogger } from 'log4js';
+import { Mutator, Mutant } from 'stryker-api/mutant';
+import { File, FileKind, TextFile } from 'stryker-api/core';
+import { Config } from 'stryker-api/config';
+import BabelParser from './helpers/BabelParser';
+import copy from './helpers/copy';
+import NodeMutatorFactory from './NodeMutatorFactory';
+import NodeMutator from './mutators/NodeMutator';
+
+function defaultMutators(): NodeMutator[] {
+  return NodeMutatorFactory.instance().knownNames().map(name => NodeMutatorFactory.instance().create(name, undefined));
+}
+
+export default class JavaScriptMutator implements Mutator {
+  private log = getLogger(JavaScriptMutator.name);
+
+  constructor(config: Config, private mutators: NodeMutator[] = defaultMutators()) {
+  }
+
+  public mutate(inputFiles: File[]): Mutant[] {
+    const mutants: Mutant[] = [];
+
+    inputFiles.filter(i => i.kind === FileKind.Text && i.mutated).forEach((file: TextFile) => {
+      const ast = BabelParser.getAst(file.content);
+      const baseAst = copy(ast, true);
+      BabelParser.removeUseStrict(baseAst);
+
+      BabelParser.getNodes(ast).forEach(node => {
+        this.mutators.forEach(mutator => {
+          let mutatedNodes = mutator.mutate(node, copy);
+
+          if (mutatedNodes) {
+            const newMutants = this.generateMutants(mutatedNodes, baseAst, file, mutator.name);
+            newMutants.forEach(mutant => mutants.push(mutant));
+          }
+        });
+      });
+    });
+
+    return mutants;
+  }
+
+  private generateMutants(nodes: babel.types.Node[], ast: babel.types.File, file: TextFile, mutatorName: string) {
+    const mutants: Mutant[] = [];
+
+    nodes.forEach(node => {
+      const replacement = BabelParser.generateCode(ast, node);
+      if (replacement) {
+        const range: [number, number] = [node.start, node.end];
+
+        const mutant = {
+          mutatorName,
+          fileName: file.name,
+          range,
+          replacement
+        };
+        this.log.trace(`Generated mutant for mutator ${mutatorName} in file ${file.name} with replacement code "${replacement}"`);
+        mutants.push(mutant);
+      }
+    });
+
+    return mutants;
+  }
+}

packages/stryker-javascript-mutator/src/NodeMutatorFactory.ts

@@ -0,0 +1,23 @@
+import { Factory } from 'stryker-api/core';
+import NodeMutator from './mutators/NodeMutator';
+
+namespace NodeMutatorFactory {
+  /**
+   * Represents a Factory for TestFrameworks.
+   */
+  class NodeMutatorFactory extends Factory<void, NodeMutator> {
+    constructor() {
+      super('nodeMutator');
+    }
+  }
+  const nodeMutatorFactoryInstance = new NodeMutatorFactory();
+
+  /**
+   * Returns the current instance of the MutatorFactory.
+   */
+  export function instance() {
+    return <Factory<void, NodeMutator>>nodeMutatorFactoryInstance;
+  }
+}
+
+export default NodeMutatorFactory;

packages/stryker-javascript-mutator/src/helpers/BabelParser.ts

@@ -0,0 +1,40 @@
+import * as babel from 'babel-core';
+import * as babylon from 'babylon';
+import generate from 'babel-generator';
+import { NodePath } from 'babel-traverse';
+
+export default class BabelParser {
+  static getAst(code: string): babel.types.File {
+    return babylon.parse(code);
+  }
+
+  static getNodes(ast: babel.types.File): babel.types.Node[] {
+    const nodes: babel.types.Node[] = [];
+
+    babel.traverse(ast, {
+      enter(path: NodePath<babel.types.Node>) {
+        const node = path.node;
+        Object.freeze(node);
+        nodes.push(node);
+      }
+    });
+
+    return nodes;
+  }
+
+  static generateCode(ast: babel.types.File, node: babel.Node) {
+    ast.program.body = [node as any];
+    return generate(ast).code;
+  }
+
+  static removeUseStrict(ast: babel.types.File) {
+    if (ast.program.directives) {
+      const directives = ast.program.directives;
+      directives.forEach((directive, index) => {
+        if (directive.value.value === 'use strict') {
+          directives.splice(index, 1);
+        }
+      });
+    }
+  }
+}

packages/stryker-javascript-mutator/src/helpers/NodeGenerator.ts

@@ -0,0 +1,13 @@
+import { types } from 'babel-core';
+
+export default class NodeGenerator {
+  static createBooleanLiteralNode(originalNode: types.Node, value: boolean): types.BooleanLiteral {
+    return {
+      start: originalNode.start,
+      end: originalNode.end,
+      loc: originalNode.loc,
+      type: 'BooleanLiteral',
+      value: value
+    };
+  }
+}

packages/stryker-javascript-mutator/src/helpers/copy.ts

@@ -0,0 +1,9 @@
+import * as _ from 'lodash';
+
+export default <T>(obj: T, deep?: boolean) => {
+  if (deep) {
+    return _.cloneDeep(obj);
+  } else {
+    return _.clone(obj);
+  }
+};

packages/stryker-javascript-mutator/src/index.ts

@@ -0,0 +1,5 @@
+import { MutatorFactory } from 'stryker-api/mutant';
+import JavaScriptMutator from './JavaScriptMutator';
+require('./mutators');
+
+MutatorFactory.instance().register('javascript', JavaScriptMutator);

packages/stryker-javascript-mutator/src/mutators/ArrayLiteralMutator.ts

@@ -0,0 +1,21 @@
+import { types } from 'babel-core';
+import NodeMutator from './NodeMutator';
+
+/**
+ * Represents a mutator which can remove the content of an array's elements.
+ */
+export default class ArrayLiteralMutator implements NodeMutator {
+  name = 'ArrayLiteral';
+
+  mutate(node: types.Node, copy: <T extends types.Node>(obj: T, deep?: boolean) => T): void | types.Node[] {
+    let nodes: types.Node[] = [];
+
+    if (types.isArrayExpression(node) && node.elements.length > 0) {
+      let mutatedNode = copy(node);
+      mutatedNode.elements = [];
+      nodes.push(mutatedNode);
+    }
+
+    return nodes;
+  }
+}