Don't crash on regex parse error

packages/instrumenter/src/mutators/regex-mutator.ts

@@ -6,21 +6,31 @@ import { NodeMutation } from '../mutant';
 
 import { NodeMutator } from '.';
 
+// function isObviousRegexString(path: NodePath<types.StringLiteral>){
+//   if(path.parentPath.isCallExpression() && path.parentPath.isNewExpression())
+// }
+
 export class RegexMutator implements NodeMutator {
   public name = 'Regex';
 
   public mutate(path: NodePath): NodeMutation[] {
     if (path.isRegExpLiteral()) {
-      return mutate(path.node.pattern, { mutationLevels: [1] }).map((mutant) => {
-        const replacement = types.cloneNode(path.node, false);
-        replacement.pattern = mutant.pattern;
-        return {
-          original: path.node,
-          replacement,
-        };
-      });
-    } else {
-      return [];
-    }
+      try {
+        return mutate(path.node.pattern, { mutationLevels: [1] }).map((mutant) => {
+          const replacement = types.cloneNode(path.node, false);
+          replacement.pattern = mutant.pattern;
+          return {
+            original: path.node,
+            replacement,
+          };
+        });
+      } catch (err) {
+        console.error(
+          `[RegexMutator]: The Regex parser of weapon-regex couldn't parse this regex pattern: "${path.node.pattern}". Please report this issue at https://github.com/stryker-mutator/weapon-regex/issues. Inner error: ${err.message}`
+        );
+      }
+    }//else if(path.isStringLiteral() && isObviousRegexString(path)){}
+    return [];
   }
+
 }

packages/instrumenter/test/unit/mutators/regex-mutator.spec.ts

@@ -0,0 +1,36 @@
+import { expect } from 'chai';
+import sinon from 'sinon';
+
+import { RegexMutator } from '../../../src/mutators/regex-mutator';
+import { expectJSMutation } from '../../helpers/expect-mutation';
+
+describe.only(RegexMutator.name, () => {
+  let sut: RegexMutator;
+  beforeEach(() => {
+    sut = new RegexMutator();
+  });
+
+  it('should have name "Regex"', () => {
+    expect(sut.name).eq('Regex');
+  });
+
+  it('should not mutate normal string literals', () => {
+    expectJSMutation(sut, '""');
+  });
+
+  it('should mutate a regex literal', () => {
+    expectJSMutation(sut, '/\\d{4}/', '/\\d/', '/\\D{4}/');
+  });
+
+  it("should not crash if a regex couldn't be parsed", () => {
+    const errorStub = sinon.stub(console, 'error');
+    expectJSMutation(sut, '/[[]]/');
+    expect(errorStub).calledWith(
+      '[RegexMutator]: The Regex parser of weapon-regex couldn\'t parse this regex pattern: "[[]]". Please report this issue at https://github.com/stryker-mutator/weapon-regex/issues. Inner error: [Error] Parser: Position 1:1, found "[[]]"'
+    );
+  });
+
+  // it('should mutate obvious Regex string literals', () => {
+  //   expectJSMutation(sut, 'new RegExp("\\d{4}", "i")', 'new RegExp("\\d", "i")', 'new RegExp("\\D{4}", "i")');
+  // });
+});