feat(TypeScript mutator): mutate Array constructor calls without the …

…new keyword (#1903) fixes #1902
stryker-mutator · Dec 1, 2019 · aecd944 · aecd944
1 parent e4c0366
commit aecd944
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Showing 2 changed files with 25 additions and 11 deletions.
diff --git a/packages/mutator-specification/src/ArrayDeclarationMutatorSpec.ts b/packages/mutator-specification/src/ArrayDeclarationMutatorSpec.ts
@@ -17,18 +17,26 @@ export default function ArrayDeclarationMutatorSpec(name: string, expectMutation
       expectMutation('[]', '["Stryker was here"]');
     });
 
-    it('should mutate filled array literals as empty arrays', () => {
+    it('should mutate filled Array constructor calls as empty arrays', () => {
       expectMutation('new Array(a, 1 + 1)', 'new Array()');
       expectMutation("new Array('val')", 'new Array()');
+      expectMutation("Array('val')", 'Array()');
+      expectMutation('Array(a, 1 + 1)', 'Array()');
     });
 
     it('should not mutate other new expressions', () => {
       expectMutation('new Object(21, 2)');
       expectMutation('new Arrays(21, 2)');
     });
 
-    it('should mutate empty array literals as a filled array', () => {
+    it('should mutate empty array constructor call as a filled array', () => {
       expectMutation('new Array()', 'new Array([])');
+      expectMutation('Array()', 'Array([])');
+    });
+
+    it('should not mutate other function call expressions', () => {
+      expectMutation('window.Array(21, 2)');
+      expectMutation('window["Array"](21, 2)');
     });
   });
 }
diff --git a/packages/typescript/src/mutator/ArrayDeclarationMutator.ts b/packages/typescript/src/mutator/ArrayDeclarationMutator.ts
@@ -2,27 +2,33 @@ import * as ts from 'typescript';
 
 import NodeMutator, { NodeReplacement } from './NodeMutator';
 
-export default class ArrayDeclarationMutator extends NodeMutator<ts.ArrayLiteralExpression | ts.NewExpression> {
+export default class ArrayDeclarationMutator extends NodeMutator<ts.ArrayLiteralExpression | ts.CallExpression | ts.NewExpression> {
   public name = 'ArrayDeclaration';
 
-  public guard(node: ts.Node): node is ts.ArrayLiteralExpression | ts.NewExpression {
-    return node.kind === ts.SyntaxKind.ArrayLiteralExpression || node.kind === ts.SyntaxKind.NewExpression;
+  public guard(node: ts.Node): node is ts.ArrayLiteralExpression | ts.CallExpression | ts.NewExpression {
+    return (
+      node.kind === ts.SyntaxKind.ArrayLiteralExpression || node.kind === ts.SyntaxKind.CallExpression || node.kind === ts.SyntaxKind.NewExpression
+    );
   }
 
-  protected identifyReplacements(node: ts.ArrayLiteralExpression | ts.NewExpression, sourceFile: ts.SourceFile): NodeReplacement[] {
+  protected identifyReplacements(
+    node: ts.ArrayLiteralExpression | ts.CallExpression | ts.NewExpression,
+    sourceFile: ts.SourceFile
+  ): NodeReplacement[] {
     if (node.kind === ts.SyntaxKind.ArrayLiteralExpression) {
       if (node.elements.length) {
         return [{ node, replacement: '[]' }];
       } else {
         return [{ node, replacement: '["Stryker was here"]' }];
       }
+    } else if (node.kind === ts.SyntaxKind.CallExpression && node.expression.kind !== ts.SyntaxKind.Identifier) {
+      // extra guard in case of a function call expression
+      return [];
     } else {
       if (node.expression.getFullText(sourceFile).trim() === 'Array') {
-        if (node.arguments && node.arguments.length) {
-          return [{ node, replacement: 'new Array()' }];
-        } else {
-          return [{ node, replacement: 'new Array([])' }];
-        }
+        const newPrefix = node.kind === ts.SyntaxKind.NewExpression ? 'new ' : '';
+        const mutatedCallArgs = node.arguments && node.arguments.length ? '' : '[]';
+        return [{ node, replacement: `${newPrefix}Array(${mutatedCallArgs})` }];
       } else {
         return [];
       }