#20 assignment operator (#46)

* WIP support for assignmentoperator * Added assignmentoperator in definitions * Added tests for edge cases * Added comments about what's being mutated * Resolved merge conflict?
brokhiv · Jan 14, 2024 · fbefe1e · fbefe1e
1 parent 21f2ba8
commit fbefe1e
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diff --git a/packages/api/schema/stryker-core.json b/packages/api/schema/stryker-core.json
@@ -271,6 +271,9 @@
         "ArrayDeclaration": {
           "$ref": "#/definitions/ArrayDeclaration"
         },
+        "AssignmentOperator": {
+          "$ref": "#/definitions/AssignmentOperator"
+        },
         "BlockStatement": {
           "$ref": "#/definitions/BlockStatement"
         },
@@ -374,6 +377,76 @@
         ]
       }
     },
+    "AssignmentOperator": {
+      "title": "AssignmentOperator",
+      "type": "array",
+      "uniqueItems": true,
+      "default": [],
+      "items": {
+        "anyOf": [
+          {
+            "const" : "+=To-=",
+            "title": "PlusAssignmentToMinusAssignmentMutator",
+            "description": "Replace ```a += b``` with ```a -= b```."
+          },
+          {
+            "const" : "-=To+=",
+            "title": "MinusAssignmentToPlusAssignmentMutator",
+            "description": "Replace ```a -= b``` with ```a += b```."
+          },
+          {
+            "const" : "*=To/=",
+            "title": "MultiplyAssignmentToDivideAssignmentMutator",
+            "description": "Replace ```a *= b``` with ```a /= b```."
+          },
+          {
+            "const" : "/=To*=",
+            "title": "DivideAssignmentToMultiplyAssignmentMutator",
+            "description": "Replace ```a /= b``` with ```a *= b```."
+          },
+          {
+            "const" : "%=To*=",
+            "title": "ModuloAssignmentToMultiplyAssignmentMutator",
+            "description": "Replace ```a %= b``` with ```a *= b```."
+          },
+          {
+            "const" : "<<=To>>=",
+            "title": "LeftShiftAssignmentToRightShiftAssignmentMutator",
+            "description": "Replace ```a <<= b``` with ```a >>= b```."
+          },
+          {
+            "const" : ">>=To<<=",
+            "title": "RightShiftAssignmentToLeftShiftAssignmentMutator",
+            "description": "Replace ```a >>= b``` with ```a <<= b```."
+          },
+          {
+            "const" : "&=To|=",
+            "title": "BitAndAssignmentToBitOrAssignmentMutator",
+            "description": "Replace ```a &= b``` with ```a |= b```."
+          },
+          {
+            "const" : "|=To&=",
+            "title": "BitOrAssignmentToBitAndAssignmentMutator",
+            "description": "Replace ```a |= b``` with ```a &= b```."
+          },
+          {
+            "const" : "&&=To||=",
+            "title": "LogicalAndAssignmentToLogicalOrAssignmentMutator",
+            "description": "Replace ```a &&= b``` with ```a ||= b```."
+          },
+          {
+            "const" : "||=To&&=",
+            "title": "LogicalOrAssignmentToLogicalAndAssignmentMutator",
+            "description": "Replace ```a ||= b``` with ```a &&= b```."
+          },
+          {
+            "const" : "??=To&&=",
+            "title": "NullishCoalescingAssignmentToLogicalAndAssignmentMutator",
+            "description": "Replace ```a ??= b``` with ```a &&= b```."
+          }
+        ]
+      }
+    },
     "BlockStatement": {
       "title": "BlockStatementMutator",
       "description": "Removes the content of every block statement.",

diff --git a/packages/instrumenter/src/mutators/assignment-operator-mutator.ts b/packages/instrumenter/src/mutators/assignment-operator-mutator.ts
@@ -1,22 +1,22 @@
-import type { types as t } from '@babel/core';
+import type { types } from '@babel/core';
 
 import { deepCloneNode } from '../util/index.js';
 
 import { NodeMutator } from './index.js';
 
 const assignmentOperatorReplacements = Object.freeze({
-  '+=': '-=',
-  '-=': '+=',
-  '*=': '/=',
-  '/=': '*=',
-  '%=': '*=',
-  '<<=': '>>=',
-  '>>=': '<<=',
-  '&=': '|=',
-  '|=': '&=',
-  '&&=': '||=',
-  '||=': '&&=',
-  '??=': '&&=',
+  '+=': { replacement: '-=', mutatorName: '+=To-=' },
+  '-=': { replacement: '+=', mutatorName: '-=To+=' },
+  '*=': { replacement: '/=', mutatorName: '*=To/=' },
+  '/=': { replacement: '*=', mutatorName: '/=To*=' },
+  '%=': { replacement: '*=', mutatorName: '%=To*=' },
+  '<<=': { replacement: '>>=', mutatorName: '<<=To>>=' },
+  '>>=': { replacement: '<<=', mutatorName: '>>=To<<=' },
+  '&=': { replacement: '|=', mutatorName: '&=To|=' },
+  '|=': { replacement: '&=', mutatorName: '|=To&=' },
+  '&&=': { replacement: '||=', mutatorName: '&&=To||=' },
+  '||=': { replacement: '&&=', mutatorName: '||=To&&=' },
+  '??=': { replacement: '&&=', mutatorName: '??=To&&=' },
 } as const);
 
 const stringTypes = Object.freeze(['StringLiteral', 'TemplateLiteral']);
@@ -25,21 +25,34 @@ const stringAssignmentTypes = Object.freeze(['&&=', '||=', '??=']);
 export const assignmentOperatorMutator: NodeMutator = {
   name: 'AssignmentOperator',
 
-  *mutate(path) {
-    if (path.isAssignmentExpression() && isSupportedAssignmentOperator(path.node.operator) && isSupported(path.node)) {
-      const mutatedOperator = assignmentOperatorReplacements[path.node.operator];
+  *mutate(path, options) {
+    if (
+      path.isAssignmentExpression() &&
+      isSupportedAssignmentOperator(path.node.operator) &&
+      isSupported(path.node) &&
+      isInMutationLevel(path.node, options)
+    ) {
+      const mutatedOperator = assignmentOperatorReplacements[path.node.operator].replacement;
       const replacement = deepCloneNode(path.node);
       replacement.operator = mutatedOperator;
       yield replacement;
     }
   },
 };
 
+function isInMutationLevel(node: types.AssignmentExpression, operations: string[] | undefined): boolean {
+  if (operations === undefined) {
+    return true;
+  }
+  const { mutatorName } = assignmentOperatorReplacements[node.operator as keyof typeof assignmentOperatorReplacements];
+  return operations.some((op) => op === mutatorName);
+}
+
 function isSupportedAssignmentOperator(operator: string): operator is keyof typeof assignmentOperatorReplacements {
   return Object.keys(assignmentOperatorReplacements).includes(operator);
 }
 
-function isSupported(node: t.AssignmentExpression): boolean {
+function isSupported(node: types.AssignmentExpression): boolean {
   // Excludes assignment operators that apply to strings.
   if (stringTypes.includes(node.right.type) && !stringAssignmentTypes.includes(node.operator)) {
     return false;

diff --git a/packages/instrumenter/test/unit/mutators/assignment-operator-mutator.spec.ts b/packages/instrumenter/test/unit/mutators/assignment-operator-mutator.spec.ts
@@ -1,7 +1,29 @@
 import { expect } from 'chai';
 
+import { MutationLevel } from '@stryker-mutator/api/core';
+
 import { assignmentOperatorMutator as sut } from '../../../src/mutators/assignment-operator-mutator.js';
-import { expectJSMutation } from '../../helpers/expect-mutation.js';
+import { expectJSMutation, expectJSMutationWithLevel } from '../../helpers/expect-mutation.js';
+
+const assignmentOperatorLevel: MutationLevel = { name: 'AssignmentOperatorLevel', AssignmentOperator: ['-=To+=', '<<=To>>=', '&&=To||='] };
+const assignmentOperatorAllLevel: MutationLevel = {
+  name: 'AssignmentOperatorLevel',
+  AssignmentOperator: [
+    '+=To-=',
+    '-=To+=',
+    '*=To/=',
+    '/=To*=',
+    '%=To*=',
+    '<<=To>>=',
+    '>>=To<<=',
+    '&=To|=',
+    '|=To&=',
+    '&&=To||=',
+    '||=To&&=',
+    '??=To&&=',
+  ],
+};
+const assignmentOperatorUndefinedLevel: MutationLevel = { name: 'AssignmentOperatorLevel' };
 
 describe(sut.name, () => {
   it('should have name "AssignmentOperator"', () => {
@@ -72,4 +94,47 @@ describe(sut.name, () => {
     expectJSMutation(sut, 'a ||= `b`', 'a &&= `b`');
     expectJSMutation(sut, 'a ??= `b`', 'a &&= `b`');
   });
+
+  it('should only mutate what is defined in the mutator level', () => {
+    expectJSMutationWithLevel(
+      sut,
+      assignmentOperatorLevel.AssignmentOperator,
+      'a += b; a -= b; a *= b; a /= b; a <<= b; a &&= b;',
+      'a += b; a += b; a *= b; a /= b; a <<= b; a &&= b;', // mutated -= to +=
+      'a += b; a -= b; a *= b; a /= b; a >>= b; a &&= b;', // mutated <<= to >>=
+      'a += b; a -= b; a *= b; a /= b; a <<= b; a ||= b;', // mutated &&= to ||=
+    );
+  });
+
+  it('should not mutate anything if there are no values in the mutation level', () => {
+    expectJSMutationWithLevel(sut, [], 'a += b; a -= b; a *= b; a /= b; a <<= b; a &&= b;');
+  });
+
+  it('should mutate everything if everything is in the mutation level', () => {
+    expectJSMutationWithLevel(
+      sut,
+      assignmentOperatorAllLevel.BooleanLiteral,
+      'a += b; a -= b; a *= b; a /= b; a <<= b; a &&= b;',
+      'a -= b; a -= b; a *= b; a /= b; a <<= b; a &&= b;', // mutated += to -=
+      'a += b; a += b; a *= b; a /= b; a <<= b; a &&= b;', // mutated -= to +=
+      'a += b; a -= b; a /= b; a /= b; a <<= b; a &&= b;', // mutated *= to /=
+      'a += b; a -= b; a *= b; a *= b; a <<= b; a &&= b;', // mutated /= to *=
+      'a += b; a -= b; a *= b; a /= b; a >>= b; a &&= b;', // mutated <<= to >>=
+      'a += b; a -= b; a *= b; a /= b; a <<= b; a ||= b;', // mutated &&= to ||=
+    );
+  });
+
+  it('should mutate everything if the mutation level is undefined', () => {
+    expectJSMutationWithLevel(
+      sut,
+      assignmentOperatorUndefinedLevel.BooleanLiteral,
+      'a += b; a -= b; a *= b; a /= b; a <<= b; a &&= b;',
+      'a -= b; a -= b; a *= b; a /= b; a <<= b; a &&= b;', // mutated += to -=
+      'a += b; a += b; a *= b; a /= b; a <<= b; a &&= b;', // mutated -= to +=
+      'a += b; a -= b; a /= b; a /= b; a <<= b; a &&= b;', // mutated *= to /=
+      'a += b; a -= b; a *= b; a *= b; a <<= b; a &&= b;', // mutated /= to *=
+      'a += b; a -= b; a *= b; a /= b; a >>= b; a &&= b;', // mutated <<= to >>=
+      'a += b; a -= b; a *= b; a /= b; a <<= b; a ||= b;', // mutated &&= to ||=
+    );
+  });
 });
diff --git a/testing-project/stryker.conf.json b/testing-project/stryker.conf.json
@@ -20,8 +20,8 @@
       "name": "default",
       "ArithmeticOperator": ["+To-", "-To+", "*To/"],
       "ArrayDeclaration": ["EmptyArray", "FilledArray", "FilledArrayConstructor"],
+      "AssignmentOperator": ["-=To+=", "<<=To>>=", "&&=To||="],
       "BooleanLiteral": ["TrueToFalse", "RemoveNegation"]
-
     },
     {
       "name": "fancy",