fix(mutant-placing): regression in optional chain (#3718)

Fix a regression in mutant placing inside an optional chain. For example: `bar?.baz[0]` ```diff - (stryMutAct_9fa48("9") ? bar.baz : (stryCov_9fa48("9"), bar?.baz)[0];" + stryMutAct_9fa48("9") ? bar.baz[0] : (stryCov_9fa48("9"), bar?.baz[0]);" ```
stryker-mutator · Sep 6, 2022 · 1228619 · 1228619
1 parent 238e5a2
commit 1228619
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Showing 4 changed files with 11 additions and 6 deletions.
diff --git a/packages/instrumenter/src/mutant-placers/expression-mutant-placer.ts b/packages/instrumenter/src/mutant-placers/expression-mutant-placer.ts
@@ -102,12 +102,13 @@ function isValidExpression(path: NodePath<babel.types.Expression>) {
    * foo.bar();
    * foo?.bar();
    * baz[foo.bar()]
+   * bar?.baz[0]
    */
   function isPartOfChain() {
     return (
       isMemberOrCallOrNonNullExpression(path) &&
-      ((isMemberExpression(parent) && !parent.node.computed) ||
-        path.isTSNonNullExpression() ||
+      ((isMemberExpression(parent) && !(parent.node.computed && parent.node.property === path.node)) ||
+        parent.isTSNonNullExpression() ||
         (isCallExpression(parent) && parent.node.callee === path.node))
     );
   }

diff --git a/packages/instrumenter/test/unit/mutant-placers/expression-mutant-placer.spec.ts b/packages/instrumenter/test/unit/mutant-placers/expression-mutant-placer.spec.ts
@@ -81,10 +81,11 @@ describe('expressionMutantPlacer', () => {
         ['foo.bar?.baz', (p) => p.isMemberExpression() && types.isIdentifier(p.node.property, { name: 'bar' })],
         ['foo?.bar.baz', (p) => p.isOptionalMemberExpression() && types.isIdentifier(p.node.property, { name: 'bar' })],
         ['foo?.bar!.baz', (p) => p.isTSNonNullExpression()],
+        ['bar?.baz[0]', (p) => p.isOptionalMemberExpression() && types.isIdentifier(p.node.object, { name: 'bar' })],
       ];
-      falsePointers.forEach(([js, query]) => {
+      falsePointers.forEach(([js, query, only]) => {
         const path = findNodePath(parseTS(js), query);
-        it(`should not allow placing in \`${path.toString()}\` of \`${js}\``, () => {
+        (only ? it.only : it)(`should not allow placing in \`${path.toString()}\` of \`${js}\``, () => {
           expect(expressionMutantPlacer.canPlace(path)).false;
         });
       });

diff --git a/packages/instrumenter/testResources/instrumenter/optional-chains.ts b/packages/instrumenter/testResources/instrumenter/optional-chains.ts
@@ -8,3 +8,5 @@ const directiveRanges = comments?.map(tryParseTSDirective)
 const qux = quux(corge?.cov());
 
 input?.id!.toString();
+
+bar?.baz[0]
diff --git a/packages/instrumenter/testResources/instrumenter/optional-chains.ts.out.snap b/packages/instrumenter/testResources/instrumenter/optional-chains.ts.out.snap
@@ -63,9 +63,10 @@ function stryMutAct_9fa48(id) {
   return isActive(id);
 }
 
-const baz = stryMutAct_9fa48(\\"0\\") ? foo?.bar?.()?.[1] && 'qux' : (stryCov_9fa48(\\"0\\"), (stryMutAct_9fa48(\\"1\\") ? foo?.bar?.()[1] : (stryCov_9fa48(\\"1\\"), (stryMutAct_9fa48(\\"3\\") ? foo.bar?.() : stryMutAct_9fa48(\\"2\\") ? foo?.bar() : (stryCov_9fa48(\\"2\\", \\"3\\"), foo?.bar?.()))?.[1])) ?? (stryMutAct_9fa48(\\"4\\") ? \\"\\" : (stryCov_9fa48(\\"4\\"), 'qux')));
+const baz = stryMutAct_9fa48(\\"0\\") ? foo?.bar?.()?.[1] && 'qux' : (stryCov_9fa48(\\"0\\"), (stryMutAct_9fa48(\\"3\\") ? foo.bar?.()?.[1] : stryMutAct_9fa48(\\"2\\") ? foo?.bar()?.[1] : stryMutAct_9fa48(\\"1\\") ? foo?.bar?.()[1] : (stryCov_9fa48(\\"1\\", \\"2\\", \\"3\\"), foo?.bar?.()?.[1])) ?? (stryMutAct_9fa48(\\"4\\") ? \\"\\" : (stryCov_9fa48(\\"4\\"), 'qux')));
 stryMutAct_9fa48(\\"5\\") ? qux().map() : (stryCov_9fa48(\\"5\\"), qux()?.map());
 const directiveRanges = stryMutAct_9fa48(\\"6\\") ? comments.map(tryParseTSDirective) : (stryCov_9fa48(\\"6\\"), comments?.map(tryParseTSDirective));
 const qux = quux(stryMutAct_9fa48(\\"7\\") ? corge.cov() : (stryCov_9fa48(\\"7\\"), corge?.cov()));
-(stryMutAct_9fa48(\\"8\\") ? input.id : (stryCov_9fa48(\\"8\\"), input?.id))!.toString();"
+stryMutAct_9fa48(\\"8\\") ? input.id!.toString() : (stryCov_9fa48(\\"8\\"), input?.id!.toString());
+stryMutAct_9fa48(\\"9\\") ? bar.baz[0] : (stryCov_9fa48(\\"9\\"), bar?.baz[0]);"
 `;