feat(Mutators): Add Boolean substitution mutators (#294)

Add boolean substitution mutator which mutates 3 things:
- `true` -> `false`
- `false` -> `true`
- `!a` -> `a`

package.json

@@ -3,6 +3,7 @@
   "devDependencies": {
     "@types/chai-as-promised": "0.0.29",
     "@types/chalk": "^0.4.28",
+    "@types/commander": "^2.9.0",
     "@types/escodegen": "0.0.6",
     "@types/esprima": "^2.1.31",
     "@types/estree": "0.0.32",

packages/stryker/.npmignore

@@ -16,7 +16,6 @@ testResources
 .tmp
 .tscache
 .vscode
-stryker.conf.js
 tsconfig.json
 /coverage
 reports

packages/stryker/src/MutatorOrchestrator.ts

@@ -5,6 +5,7 @@ import RemoveConditionalsMutator from './mutators/RemoveConditionalsMutator';
 import UnaryOperatorMutator from './mutators/UnaryOperatorMutator';
 import UpdateOperatorMutator from './mutators/UpdateOperatorMutator';
 import ArrayDeclaratorMutator from './mutators/ArrayDeclaratorMutator';
+import BooleanSubstitutionMutator from './mutators/BooleanSubstitutionMutator';
 import { Mutator, MutatorFactory } from 'stryker-api/mutant';
 import { SourceFile } from 'stryker-api/report';
 import Mutant from './Mutant';
@@ -86,6 +87,7 @@ export default class MutatorOrchestrator {
     mutatorFactory.register('UnaryOperator', UnaryOperatorMutator);
     mutatorFactory.register('UpdateOperator', UpdateOperatorMutator);
     mutatorFactory.register('ArrayDeclarator', ArrayDeclaratorMutator);
+    mutatorFactory.register('BooleanSubstitution', BooleanSubstitutionMutator);
   }
 
   /**

packages/stryker/src/mutators/BooleanSubstitutionMutator.ts

@@ -0,0 +1,26 @@
+import { Mutator, IdentifiedNode } from 'stryker-api/mutant';
+import { Syntax } from 'esprima';
+
+export default class BooleanSubstitutionMutator implements Mutator {
+  name = 'BooleanSubstitution';
+
+  applyMutations(node: IdentifiedNode, copy: <T>(obj: T, deep?: boolean) => T): IdentifiedNode[] {
+    const nodes: IdentifiedNode[] = [];
+
+    // !a -> a
+    if (node.type === Syntax.UnaryExpression && node.operator === '!') {
+      let mutatedNode = copy(node.argument) as IdentifiedNode;
+      mutatedNode.nodeID = node.nodeID;
+      nodes.push(mutatedNode);
+    }
+
+    // true -> false or false -> true
+    if (node.type === Syntax.Literal && typeof node.value === 'boolean') {
+      let mutatedNode = copy(node);
+      mutatedNode.value = !mutatedNode.value;
+      nodes.push(mutatedNode);
+    }
+    return nodes;
+  }
+
+}

packages/stryker/src/stryker-cli.ts

@@ -1,4 +1,4 @@
-const program = require('commander');
+import * as program from 'commander';
 import { CONFIG_SYNTAX_HELP } from './ConfigReader';
 import Stryker from './Stryker';
 import * as log4js from 'log4js';
@@ -40,20 +40,20 @@ Optional location to the stryker.conf.js file as last argument. That file should
 log4js.setGlobalLogLevel(program['logLevel'] || 'info');
 
 // Cleanup commander state
-delete program.options;
-delete program.rawArgs;
+delete program['options'];
+delete program['rawArgs'];
 delete program.args;
 delete program.Command;
 delete program.Option;
-delete program.commands;
+delete program['commands'];
 for (let i in program) {
   if (i.charAt(0) === '_') {
     delete program[i];
   }
 }
 
 if (strykerConfig) {
-  program.configFile = strykerConfig;
+  program['configFile'] = strykerConfig;
 }
 
 const commands: { [cmd: string]: () => void } = {

packages/stryker/stryker.conf.js

@@ -8,4 +8,4 @@ module.exports = function (config) {
     logLevel: 'info',
     plugins: ['stryker-mocha-runner']
   });
-};
+};

packages/stryker/test/unit/mutators/BooleanSubstitutionMutatorSpec.ts

@@ -0,0 +1,74 @@
+import { expect } from 'chai';
+import * as estree from 'estree';
+import { Identified, IdentifiedNode } from 'stryker-api/mutant';
+import BooleanSubstitutionMutator from '../../../src/mutators/BooleanSubstitutionMutator';
+import { parse, generate } from '../../../src/utils/parserUtils';
+import { copy } from '../../../src/utils/objectUtils';
+
+describe('BooleanSubstitutionMutator', () => {
+  let sut: BooleanSubstitutionMutator;
+
+  beforeEach(() => {
+    sut = new BooleanSubstitutionMutator();
+  });
+
+  it('should mutate when supplied a expression with !', () => {
+    // Arrange
+    const program = parse(`!a.a()`);
+    const nodeUnaryExpression = ((program.body[0] as estree.ExpressionStatement).expression as estree.UnaryExpression & Identified);
+
+    // Act
+    const result = sut.applyMutations(nodeUnaryExpression, copy)[0] as estree.Expression & Identified;
+
+    // Assert
+    expect(result).to.be.ok;
+    expect(result.type).to.be.eq(nodeUnaryExpression.argument.type);
+    expect(result.nodeID).to.be.eq(nodeUnaryExpression.nodeID);
+    expect(generate(result)).to.be.eq('a.a()');
+  });
+
+  it('should mutate true -> false', () => {
+    // Arrange
+    const program = parse(`true`);
+    const nodeLiteral = ((program.body[0] as estree.ExpressionStatement).expression as estree.Literal & Identified);
+
+    // Act
+    const result = sut.applyMutations(nodeLiteral, copy)[0] as estree.Literal & Identified;
+
+    // Assert
+    expect(result).to.be.ok;
+    expect(result.value).to.be.false;
+    expect(result.nodeID).to.be.eq(nodeLiteral.nodeID);
+    expect(generate(result)).to.be.eq('false');
+  });
+
+  it('should mutate false -> true', () => {
+    // Arrange
+    const program = parse(`false`);
+    const nodeLiteral = ((program.body[0] as estree.ExpressionStatement).expression as estree.Literal & Identified);
+
+    // Act
+    const result = sut.applyMutations(nodeLiteral, copy)[0] as estree.Literal & Identified;
+
+    // Assert
+    expect(result).to.be.ok;
+    expect(result.value).to.be.true;
+    expect(result.nodeID).to.be.eq(nodeLiteral.nodeID);
+    expect(generate(result)).to.be.eq('true');
+  });
+
+  it('should not mutate other nodes', () => {
+    // Arrange
+    const invalidNode: IdentifiedNode = {
+      type: 'Identifier',
+    } as estree.Node & Identified;
+
+    // Act
+    const result = sut.applyMutations(invalidNode, copy);
+
+    // Assert
+    expect(result).to.have.lengthOf(0);
+  });
+
+
+});

sampleProject/src/Add.js

@@ -22,3 +22,19 @@ var isNegativeNumber = function(number) {
   }
   return isNegative;
 };
+
+var isTrue = function(boolean) {
+  return boolean === true;
+};
+
+var isFalse = function(boolean) {
+  return boolean === false;
+};
+
+var getOppositeBoolean  = function(boolean) {
+  if(!boolean){
+    return true;
+  } else {
+    return false;
+  }
+};

sampleProject/test/AddSpec.js

@@ -42,4 +42,16 @@ describe('Add', function() {
 
     expect(isNegative).toBe(false);
   });
+
+  it('should be able to recognize that true = true', function() {
+    expect(isTrue(true)).toBe(true);
+  });
+
+  it('should be able to recognize that false = false', function() {
+    expect(isFalse(false)).toBe(true);
+  });
+
+  it('should be able to recognize that !true = false', function() {
+    expect(getOppositeBoolean(true)).toBe(false);
+  });
 });