From 8c8b47819a6f415c0da773888ed7692cf5d76776 Mon Sep 17 00:00:00 2001
From: Nico Jansen <jansennico@gmail.com>
Date: Thu, 8 Oct 2020 16:40:50 +0200
Subject: [PATCH] fix(string-literal-mutator): don't mutate class property keys
 (#2544)

Don't mutate class property keys that are written as a string literal.

```ts
class Foo {
  'bar-baz': 4 // don't mutate
}
```
---
 .../src/mutators/string-literal-mutator.ts          |  1 +
 .../test/integration/instrumenter.it.spec.ts        |  3 +++
 .../unit/mutators/string-literal-mutator.spec.ts    |  6 ++++++
 .../testResources/instrumenter/string-mutations.ts  |  7 +++++++
 .../instrumenter/string-mutations.ts.out.snap       | 13 +++++++++++++
 5 files changed, 30 insertions(+)
 create mode 100644 packages/instrumenter/testResources/instrumenter/string-mutations.ts
 create mode 100644 packages/instrumenter/testResources/instrumenter/string-mutations.ts.out.snap

diff --git a/packages/instrumenter/src/mutators/string-literal-mutator.ts b/packages/instrumenter/src/mutators/string-literal-mutator.ts
index eed6d19cb3..4b29b8bd36 100644
--- a/packages/instrumenter/src/mutators/string-literal-mutator.ts
+++ b/packages/instrumenter/src/mutators/string-literal-mutator.ts
@@ -40,6 +40,7 @@ export class StringLiteralMutator implements NodeMutator {
       types.isExpressionStatement(parent) ||
       types.isTSLiteralType(parent) ||
       (types.isObjectProperty(parent) && parent.key === child.node) ||
+      (types.isClassProperty(parent) && parent.key === child.node) ||
       (types.isCallExpression(parent) && types.isIdentifier(parent.callee, { name: 'require' }))
     );
   }
diff --git a/packages/instrumenter/test/integration/instrumenter.it.spec.ts b/packages/instrumenter/test/integration/instrumenter.it.spec.ts
index f6a81db93a..d31bfec03f 100644
--- a/packages/instrumenter/test/integration/instrumenter.it.spec.ts
+++ b/packages/instrumenter/test/integration/instrumenter.it.spec.ts
@@ -55,6 +55,9 @@ describe('instrumenter integration', () => {
   it('should be able to instrument switch case statements (using the switchCaseMutantPlacer)', async () => {
     await arrangeAndActAssert('switch-case.js');
   });
+  it('should be able to instrument string literals in different places', async () => {
+    await arrangeAndActAssert('string-mutations.ts');
+  });
 
   describe('type declarations', () => {
     it('should not produce mutants for TS type definitions', async () => {
diff --git a/packages/instrumenter/test/unit/mutators/string-literal-mutator.spec.ts b/packages/instrumenter/test/unit/mutators/string-literal-mutator.spec.ts
index 51d1d538ff..c04500975e 100644
--- a/packages/instrumenter/test/unit/mutators/string-literal-mutator.spec.ts
+++ b/packages/instrumenter/test/unit/mutators/string-literal-mutator.spec.ts
@@ -87,6 +87,12 @@ describe(StringLiteralMutator.name, () => {
     it('should still mutate inside object property values', () => {
       expectJSMutation(sut, 'const foo = { bar: "baz" };', 'const foo = { bar: "" };');
     });
+    it('should not mutate class property keys', () => {
+      expectJSMutation(sut, 'class Foo { "baz-bar" = 4; }');
+    });
+    it('should mutate class property values', () => {
+      expectJSMutation(sut, 'class Foo { bar = "4"; }', 'class Foo { bar = ""; }');
+    });
   });
 
   describe('jsx', () => {
diff --git a/packages/instrumenter/testResources/instrumenter/string-mutations.ts b/packages/instrumenter/testResources/instrumenter/string-mutations.ts
new file mode 100644
index 0000000000..d842c0e27f
--- /dev/null
+++ b/packages/instrumenter/testResources/instrumenter/string-mutations.ts
@@ -0,0 +1,7 @@
+require('foo'); // no mutation
+import 'foo'; // no mutation
+
+class Foo {
+  public 'bar-baz': string; // no mutation
+}
+
diff --git a/packages/instrumenter/testResources/instrumenter/string-mutations.ts.out.snap b/packages/instrumenter/testResources/instrumenter/string-mutations.ts.out.snap
new file mode 100644
index 0000000000..b995317096
--- /dev/null
+++ b/packages/instrumenter/testResources/instrumenter/string-mutations.ts.out.snap
@@ -0,0 +1,13 @@
+// Jest Snapshot v1, https://goo.gl/fbAQLP
+
+exports[`instrumenter integration should be able to instrument string literals in different places 1`] = `
+"require('foo'); // no mutation
+
+
+import 'foo'; // no mutation
+
+class Foo {
+  public 'bar-baz': string; // no mutation
+
+}"
+`;