fix(shebang): support shebang in in files (#2510)

Support shebang (i.e. `#!/usr/bin/env node`) in javascript files.

e2e/test/mocha-javascript/src/Add.js

@@ -1,3 +1,4 @@
+#! /usr/bin/env node
 module.exports.add = function(num1, num2) {
   return num1 + num2;
 };

packages/instrumenter/src/disable-type-checks.ts

@@ -35,7 +35,17 @@ function disableTypeCheckingInBabelAst(ast: JSAst | TSAst): string {
 }
 
 function prefixWithNoCheck(code: string): string {
-  return `// @ts-nocheck\n${code}`;
+  if (code.startsWith('#')) {
+    // first line has a shebang (#!/usr/bin/env node)
+    const newLineIndex = code.indexOf('\n');
+    if (newLineIndex > 0) {
+      return `${code.substr(0, newLineIndex)}\n// @ts-nocheck\n${code.substr(newLineIndex + 1)}`;
+    } else {
+      return code;
+    }
+  } else {
+    return `// @ts-nocheck\n${code}`;
+  }
 }
 
 function disableTypeCheckingInHtml(ast: HtmlAst): string {

packages/instrumenter/test/integration/disable-type-checks.it.spec.ts

@@ -20,7 +20,7 @@ const resolveTestResource = path.resolve.bind(
 );
 
 describe(`${disableTypeChecks.name} integration`, () => {
-  it('should be able disable type checks of a type script file', async () => {
+  it('should be able disable type checks of a typescript file', async () => {
     await arrangeAndActAssert('app.component.ts');
   });
   it('should be able disable type checks of an html file', async () => {

packages/instrumenter/test/integration/instrumenter.it.spec.ts

@@ -46,6 +46,9 @@ describe('instrumenter integration', () => {
   it('should be able to instrument super calls', async () => {
     await arrangeAndActAssert('super-call.ts');
   });
+  it('should be able to instrument js files with a shebang in them', async () => {
+    await arrangeAndActAssert('shebang.js');
+  });
 
   describe('type declarations', () => {
     it('should not produce mutants for TS type definitions', async () => {

packages/instrumenter/test/unit/disable-type-checks.spec.ts

@@ -14,6 +14,19 @@ describe(disableTypeChecks.name, () => {
       assertions.expectTextFileEqual(actual, new File('foo.js', '// @ts-nocheck\nfoo.bar();'));
     });
 
+    describe('with shebang (`#!/usr/bin/env node`)', () => {
+      it('should insert `// @ts-nocheck` after the new line', async () => {
+        const inputFile = new File('foo.js', '#!/usr/bin/env node\nfoo.bar();');
+        const actual = await disableTypeChecks(inputFile, { plugins: null });
+        assertions.expectTextFileEqual(actual, new File('foo.js', '#!/usr/bin/env node\n// @ts-nocheck\nfoo.bar();'));
+      });
+      it('should not insert if there is no code', async () => {
+        const inputFile = new File('foo.js', '#!/usr/bin/env node');
+        const actual = await disableTypeChecks(inputFile, { plugins: null });
+        assertions.expectTextFileEqual(actual, new File('foo.js', '#!/usr/bin/env node'));
+      });
+    });
+
     it('should not even parse the file if "@ts-" can\'t be found anywhere in the file (performance optimization)', async () => {
       const createParserSpy = sinon.spy(parsers, 'createParser');
       const inputFile = new File('foo.js', 'foo.bar();');

packages/instrumenter/testResources/disable-type-checks/app.component.ts.out.snap

@@ -65,3 +65,36 @@ export class AppComponent {
 }
 "
 `;
+
+exports[`disableTypeChecks integration should be able disable type checks of a typescript file 1`] = `
+"// @ts-nocheck
+import {Component, HostListener, Inject} from '@angular/core';
+import {DOCUMENT} from '@angular/common';
+
+@Component({
+  selector: 'ksw-root',
+  templateUrl: './app.component.html',
+  styleUrls: ['./app.component.scss']
+})
+export class AppComponent {
+  title = 'Kantishop';
+
+  constructor(@Inject(DOCUMENT) document) {
+  }
+
+  @HostListener('window:scroll', ['$event'])
+  onWindowScroll(e) {
+    // 
+    if (window.pageYOffset > document.getElementById('banner').offsetHeight) {
+      const element = document.getElementById('kanti-menu');
+      element.classList.add('kanti-sticky');
+      document.getElementsByTagName('main').item(0).setAttribute('style', 'margin-top: 50px');
+    } else {
+      const element = document.getElementById('kanti-menu');
+      element.classList.remove('kanti-sticky');
+      document.getElementsByTagName('main').item(0).removeAttribute('style');
+    }
+  }
+}
+"
+`;

packages/instrumenter/testResources/instrumenter/shebang.js

@@ -0,0 +1,3 @@
+#! /usr/bin/env node
+
+console.log('test');

packages/instrumenter/testResources/instrumenter/shebang.js.out.snap

@@ -0,0 +1,61 @@
+// Jest Snapshot v1, https://goo.gl/fbAQLP
+
+exports[`instrumenter integration should be able to instrument js files with a shebang in them 1`] = `
+"#! /usr/bin/env node
+
+function stryNS_9fa48() {
+  var g = new Function(\\"return this\\")();
+  var ns = g.__stryker__ || (g.__stryker__ = {});
+
+  if (ns.activeMutant === undefined && g.process && g.process.env && g.process.env.__STRYKER_ACTIVE_MUTANT__) {
+    ns.activeMutant = Number(g.process.env.__STRYKER_ACTIVE_MUTANT__);
+  }
+
+  function retrieveNS() {
+    return ns;
+  }
+
+  stryNS_9fa48 = retrieveNS;
+  return retrieveNS();
+}
+
+stryNS_9fa48();
+
+function stryCov_9fa48() {
+  var ns = stryNS_9fa48();
+  var cov = ns.mutantCoverage || (ns.mutantCoverage = {
+    static: {},
+    perTest: {}
+  });
+
+  function cover() {
+    var c = cov.static;
+
+    if (ns.currentTestId) {
+      c = cov.perTest[ns.currentTestId] = cov.perTest[ns.currentTestId] || {};
+    }
+
+    var a = arguments;
+
+    for (var i = 0; i < a.length; i++) {
+      c[a[i]] = (c[a[i]] || 0) + 1;
+    }
+  }
+
+  stryCov_9fa48 = cover;
+  cover.apply(null, arguments);
+}
+
+function stryMutAct_9fa48(id) {
+  var ns = stryNS_9fa48();
+
+  function isActive(id) {
+    return ns.activeMutant === id;
+  }
+
+  stryMutAct_9fa48 = isActive;
+  return isActive(id);
+}
+
+console.log(stryMutAct_9fa48(0) ? \\"\\" : (stryCov_9fa48(0), 'test'));"
+`;